I appreciate all the comments and critiques! This is an older video that I learned a lot from, and I've since tried a few different ways of explaining ground side voltage drop. I hope you will all sub to our channel and check out the entire "Trainer" library. THANKS!
Motor Age This is by far the BEST way I’ve ever heard it explained. No one EVER really explained what and why your car’s chassis is used as ground! So simple, but a lot of people may not know that!
yeah! your stuff exposes much that is missing in the understanding of automotive and electrical control. I am critical(constructively) but I appreciate your work. ...and I am subscribed...
I will be referring your efforts to a few classes of grade six's as I do lectures on their Flight then Electricity portions of their curriculum. Very well done video! The half split method demo'd is crucial in troubleshooting 👏
As a Mechanic of 40 years and Shop owner I’d like to Thank You. This type of video training is desperately needed, it never ceases to amaze me how many mechanics come through my shop and are absolutely Clueless about electrical basics but claim to be diagnostic Techs... now, with these videos I can educate my trainees without going broke
That's great! Glad you and your team find it helpful. That's what we do at @MotorAgeMagazine - "advancing the automotive service professional" since 1899.
Makes a fella wonder if scientists today could operate a slide rule in case our chinese pals launched a EMP and shredded computer networks. They may have changed this because it made sense (we can't have that). The Navy uses all manner of hi tech technology but they still train Quartermasters to navigate the same way Columbus did. It's like banning calculators from math class.
I experienced the same issue when I owned my shop th-cam.com/video/DA4vl2CsMSY/w-d-xo.html when I would get other shops referring a customer over for a problem they couldn't figure out and it would often turn out to be a failure of basic battery or charging system testing 🤦🏼♂️
I've been a DIY for a few years now, gaining much more confidence. The sad part is, in my area. You need to have your certifications complete to even be considered. (my experience does not apply to all shops and areas/city/states). I have high aptitude for electrical, and not mechanical since i've DIY put many parts in my own vehicles. This is a great video, to be honest, you really do need to practice practice practice. There's no replacement for learning the basics through trial and error. Other day i was testing a starter, before realizing.. (duh), i need lower AWG conductor that can handle the voltage and current to run the motor. Used some jumpers, BAM.. power. Another tip for future technicians, it's NEVER too late to learn the basics.
I tell my kids the same. It's like try to use your left hand as much as you can, even tight a shoe, drinking coffee, you never know, when it will be the only hand left to use it. And you mentioned sliding ruler, about a cashier or bank clerk, figuring out how much change is due back to a customer? 🤣🤣. AI will not longer work also, but God
Trainer, You Sir, are a true Teacher! Out of my 65 years on this earth, I've never heard of anyone explaining a "Voltage Drop Test" in such a Pure and Simple too the point presentation. You take the saying of "Explain it too me like I was 9 year old" too a whole other level. Great Job mister!
I have a degree in automotive science and I've been certified twice as a master auto technician and I'm impressed with this gentleman's approach to teaching these concepts.
I am so very glad that you said the “Fuse” is their to protect the wiring. Although explaing why it’s on the positive side was a nice touch, but while the component is designed to be changed, the wiring harness is not. Depending on where you grew up and how, like a farm, there where not a lot to trade schools near by to attend to learn automotive mechanics. The high school did not even offer it or woodworking. But, I asked questions, watched others and most importantly did my own work. Having my cousins bring an old school, rope wound go cart to the farm for use 3 months of the year, was the one thing I feel in love with. Wheels, going fast and the freedom, but it quit. It was a huge incentive to learn how to diagnose a small gas engine, basically graduating from taking two lawn mowers and making one run. Considering we did not get an allowance, a gas engine make earning that $1 per yard easier. Fixed the go-cart and was saved from the butt-kicking I would get from my older and bigger cousins next summer. Being an apprentice in a one man shop is still possible but more rare with the complexity of systems. As paper factory service manuals where normal, few of us still remember the back page with the schematic for the vehicle and it’s variations where found. Yes, they folded out 8, 10 or 12 pages but the head light where on the left or first page, while the tag, tail and stop lights where on the last page or right. Everything else in the vehicle was in the middle with no rectangular boxes that said “Logic” inside. Best of all, no two techs having the same talents they put descriptions of voltage drop and other meaningful information in the beginning of that section. You could walk into a dealer, line up 20 techs and ask to describe voltage drop and only one or two hands at best would go up. Not much better today but I found it to be the easiest, quickest and it never lyes. Best of all, you did not disturbed the other wires, connectors or terminals, in case it was an intermittent problem that was acting up for four days straight. Working at a Buick, try explaining to a 70 to 80 year old man why the radio, windows, wipers or sunroof worked, with the key off, then quit when you opened the door! It was a short I tell you! No, read page 66 of the owners manual under features. Thanks for the wonderful and good video! ASE Master Tech since 1978 - Retired
Voltage drop was a life-changer as a dealer tech. Every new tech needs this video as a primer to step into the shop. You are are a gentleman and a scholar, and even more, you are a teacher among teachers, sir.
You have got to be kidding. I taught electronics in the military and civilian sectors and, though you may know what you're wishing to convey, they way you convey it is convoluted and confusing. Even your mockup with the two bulbs as resistances in a circuit is confusing because you have another black line representing a circuit path shorting the "unwanted resistance." Why would you do this to people who are already struggling to understand what you're trying to convey? The fact that you call the red lead of the DMM the "positive lead" and the black lead the "negative lead" shows a fundamental misunderstanding of how to use a DMM. The black lead is the REFERENCE lead and the red lead is the MEASUREMENT lead. There are systems that are positive ground where the reference lead will be on the most positive side of the power source. Telecommunication DC plants are like this and are -48VDC, typically. When you see a measurement, the reading is IN REFERENCE to the black lead and it may be positive or negative but you know it is WITH RESPECT to the reference lead. Telling people that "voltage is consumed" by a load is also just confusing since there is no physical way to demonstrate this. It's just as easy to teach electrical fundamentals CORRECTLY as it is to BS your way through it. I'm a retired engineer/teacher and what you did in these 9+ minutes is just cringe. Telling people to remember adages instead of explaining the "why" of it only makes things easier on YOU, not on the pupil. SMH Awful. Just awful. THIS is why people think electronics and/or math is difficult... they think if they don't understand something it's because they're just not getting it when, in fact, it is the horrendous teaching abilities of the person in from of them.
@@DiffEQin the automotive world, nearly everything is 12 volt D.C. negative ground. The only thing I’ve ever seen with a positive ground is a Ford tractor from the 1950s that was 6 volt.
@@DiffEQ Please direct us to your video on this topic so that we can learn something. I see that some other people have made the same request, so please edumacate us!
Man, this is an awesome video, and you are a great instructor! No silly, flashy crap; just clear, concise and coherent. I already knew a lot of this information, but I often watch videos on topics about which I am already fairly knowledgeable in order to see if there's a better way or something I've missed in my years of doing this kind of work. So glad I did! Thanks!
When I was 18 ,I had an issue with the frequency valve on a Bosch CIS injection setup. I had power at the plug ,but it wouldn't operate. I swapped it out ,same thing. Haha ,dad ,help!! He's not an auto tech by any means ,but an engineer and I never recall bringing our cars to the shop. After 30-40mins ,he found it and it was a broken wire in the harness. I was amazed because he came into it saying he "didn't know anything about these cars". Probably part of what made me go to tech school and see if I could learn what he knew. He always took time to explain it but the formal training was a big help.
@@tmanda323 ... surely you have repaired it by now, or it could ruin the entire thing. Some examples: - it could be a simple switch and/or wiring issue. - AC clutch burn out - compressor overheating( short cycling, lack of external cooling, poor ventilation, low suction pressure, high head pressure, poor lubrication, wear and tear/getting old... that can cause electrical problems) - A short can ruin the clutch, and a cascade of other things that are mechanically attached, like the belt system, ... weak charging, overworking the alternator, ...
3 years of engineering at university (and flunking electrical engineering a few times) still failed to help me fully understand what this video clarified in less than 10mins !!!
I'm was an Electrical Engineer earlier in my career and now am a handyman. Funny how the simplest of things can stump someone who should know. Great video!
I'm an engineer (not EE, but I am involved in amateur radio and I fix my own vehicles). FIRST thing I thought was _ground loop_ but some kind of parasitic drain in a car nowadays is almost always going to happen some time or another. It's gotten to the point we have TOO MUCH electronics in cars now.
Stumbled across this video while looking for something else. Voltage drop is such an easy way to diagnose electrical issues and so few people know how to use it. I started in life as an auto tech many years ago but left it behind to become an electrician. I had a crusty ole mechanic show me how to check voltage drop when I was just starting out and actually created the interest in electricity that eventually lead me to leave the auto repair world. i am still heavily involved with classic cars and the go to guy at work when people have car troubles. I can't tell you how many fellow electricians l have had to school on voltage drop and how easy it is to diagnose problems using this technique. You're correct, figure out what voltage drop Is, how to measure it and what the meter is telling you and electrical problems will no longer be a problem. Thanks for sharing the video.
Great story! If that crusty old mechanic is still alive, maybe you can let him know how much he did for you. Although, I’m guessing you already have. Cheers
HotRod Ray my son is an auto tech at a dealership. I told him before he went to tech school, if he would learn only the electrical side of automotive work, he would always be in demand as a tech. So few understand the principals, but 99% think they know everything about it! That 1% that know they do not understand everything about that electrical system are the ones that best understand those systems!
Some mechanics with a car that is totally dead with a good battery will tell you the electrical system is fried or some other word indicating you cars electrical system has gone out like a watch or radio or cell phone that has bricked. It indicates he does not know electrical very well and therefore he is going to start swapping part, probably starting with the expensive computer an hopes he get lucky. That is why you know how to use a diagnostic plug and know the computer is involved if the plug does not work. Unfortunately at that point you probably need an electrical diagram to check the voltages on the plug going into the computer and some advanced electrical components to do that while it is plugged in like a probe that penetrates the wires.
I've been a mechanic for quite a while and have worked in several shops but really never learned the electrical aspect of it because like probably a lot of shops we had a go to guy because I think that is pretty common in shops. anyway I got out of the business around 2003 and now want to get back in to working on cars but instead of just getting by I want to under stand the electrical system as good as I can. I like your down to earth teaching style and I am starting to learn on my journey back into the business . Thank you for your sacrifice.
If I had a friend, I would definitely share this! (Been messing with cars and machinery for 2/3rds of my life...but I can still learn something from a great basic instructional like this. The model circuit used for illustration really hits a home run!)
I read the title and instantly knew what was coming. It's a very basic principle that too many greenhorns overlook. I watched a guy change a fuel pump three times before I took over and found that the customer had disconnected the ground for that circuit so he could install a boom box in his trunk. It's not enough to know that something isn't working, you have to know why.
@Yard Sale Dale - I'm sure that was exactly what the supervisor asked him. I wasn't there for that conversation. Was it a lack of know how or imagination? Your guess is as good as mine.
I have an electrical engineering degree but don't know where to start with car electrical because I do not have a schematic and have know what explain the basics of a schematic (if I had on) to me. I watch these and other people explaining electrical problems because these are very expensive repairs I could do myself and can be useful when electrical problems strand you on a trip. This video basically says always check both sides of a load to the body, because in many of the repair videos the pathway to one side or the other (+ or -) is compromised. Someone did a video of checking the computers harness to verify the computer is the problem and not the harness voltages. Another is the battery, wiring/fuses, solenoid, or starter the problem by looking a voltages while attempting to start the car. Knowing how to use a diagnostic plug to take a first pass at a problem is also useful.
I changed my head gasket went to start truck . Starter burnt out . I fixed it went to start truck . No fuel. Pump not running. Well I just got pump off. Is there anyway I unhooked a wire some where. Or is it my fuel pump. I went from head gasket to waterpump it started for a second . Shut off just was checking time before fan and stuff so maybe enough gas to barely start idk. But after together and starter issue . No gas pressure no noise from tank. And I wasn't pulling bed off I took tank down. If anything I'm going to try run wire to pump. Just cold out now. And if ain't pump on Ford ranger maybe u might have idea. Ty if u read this
@@gordontrainer3546 is the ground cable from the battery connected to the engine block? And is the ground strap from the head connected to the cars body? The body/chassis ground engine ground, are the sources the other grounds use for a path to the negative battery post. Sometimes people don't put things back or put them back differently because they aren't somebody who does that work with repetition. Did you take anything else apart? Are the connections in good repair and not corroded? Retrace your steps inspecting what you had to do and if you can't find something, diagnose the fuel pumps operation as per the service manual. You can get literature free on library databases from home using a library card. Some data bases, you go to a library for access. Print your pages and return. That's what I do if I need familiarity and a map and procedure. A fuel pump uses an inertia switch as a shut off for safety. It uses a fuel pump relay. It is turned on and off by a PCM. The PCM must have signal spark is working or it can shut fuel pressure down for safety. This is why having service manuals can help, knowing how the circuit works and what components are included in the circuit. Fuel delivery can be shut down as well by antitheft . You know you are working with pressure loss of supply because you don't hear the pump run. Stick to why that is first, as you probably know. But only you know what change could be likely to have been caused, since it worked before you began. Locations of components is also info service manuals provide. A good portion of what they publish is correct. A small portion needs updating or correcting to be less vague. You said it seemed to run for a second. This could be a clue it can run but is being interrupted. You write some phrases that raise more questions. I won't be able to go back and forth. You can do that with an online tech assistance and read other people's fixes for their circumstances. They made Rangers for a great number of years. Always refer to year/make/model, engine size, trans type, unusual options. Then the helper can picture what components and systems are in use on yours and particular info to yours. Good luck. This tape will self destruct in 5 seconds.
@@gordontrainer3546 You just took the car apart and now you don't have fuel pressure. The very first thing is to double check your work. Many computers are designed so that if a crucial sensor is giving a signal that would indicate the engine shouldn't be running, the computer will cut fuel or ignition. A disconnected or damaged sensor can trigger this. So, check to make sure everything is plugged in and undamaged. That includes the wires that carry the signals. Did you check the fuel pump fuse? Did you check for power at the fuse? Did you check for power and signal at the relay? Did you try swapping a known good relay in, to test the relay? Did you check for power at the tank? Did you check for ground at the tank? All of these tests should be run before removing the tank and the pump. There are no returns on electrical parts. Running a raw wire to the fuel pump is a recipe for disaster.
Pete, I just recently "stumbled" across your video series while in the process of looking for something else. I've watched a handful of them on electricity and electrical diagnosis, and I'm impressed with your skill as an instructor. You clearly know how to share what can be a challenging subject in a manner that is readily understandable. In this video, I particularly appreciated your taking the time (at 2:20) to explain why the circuit protection device is always placed on the positive side of the circuit. I would add that this device should always be placed as close to the battery's positive terminal post as possible, the reason being that it increases the likelihood that the device would still be included in the circuit in the event of a short circuit prior to the load.
Hey thank you!!!!!!! You explained it better than anyone else on here. I'm working on a 1988 Ford F250 diesel with the glow plugs not firing and a voltage drop.I'm not a professional mechanic and It's in my driveway currently, Now I know where and how to start troubleshooting it. THANKS A MILLION!!!!!
Hey Pete. I hope you're still around. I just found these and want to thank you for a well produced and simply explained series. I know all of this stuff but have been looking for links to send the many people who ask me for advice. These are so well done and explained. They are a great resource!!
this video is a definite part of my level up. i've had about 8v on my chasis, measuring from the negative post and i've been racking my brain how that could be. now i know. thank you Sir!
but also, what if i disconnect the positive terminal from the battery, and i measure voltage from neg post (disconnected) to chasis ground. internal short of battery?
Good stuff. High resistance in the positive side of the circuit leads to this situation: The lamp won't light. Re-lamp no help. We know that the lamp will operate when we connect +12 volts on one terminal, and a ground on the other. We remove the lamp, measure 12 volts on one terminal and a good ground on the other. We reinstall the lamp, it still does not light. What did we miss? We know the ground is good because we measured it with an ohmmeter. We assumed the positive (power) side is good because we measured full battery voltage on it. BUT, we had to remove the lamp, which is the load in the circuit, to put the positive meter lead on the terminal in the socket. We have now replaced the normal load, which draws a current of, say, half an amp, with the meter, which draws a current of--guess what--practically zero amps. Voltmeters have very high internal resistance, typically in the millions of ohms. If you have a corroded or damaged connection or wire on the positive side of the circuit, even if adds thousands of ohms of resistance, the tiny current drawn by the meter will not cause a noticeable voltage drop in your measurement. So you measure twelve volts at the terminal with the lamp removed, but when you replace the lamp in the socket, any current it draws will cause most or all of the voltage to be dropped across the high resistance of the fault. The voltage you thought you had measured disappears the instant the normal load is inserted into the circuit. This is why you always attempt to make your voltage measurements in a complete circuit, with the load connected and any switches turned on.
You cannot measure the return with an Ohm meter and call it good. That's the problem with hack teachers like this guy.... they don't really explain anything and make up things like "consumes the voltage." Absurd. Not all things are Ohmic. Incandescent filaments are a prime example... measured with an Ohm meter you will get nearly a direct short (depending on the bulb Wattage and voltage rating). You know that can't be. What happens is that the filament has a positive temperature coefficient and the resistance rise as it heats up. Your claim that a multimeter will not measure thousands of Ohms of resistance because the current is too low is grossly incorrect. Even at just 1 Ohms of resistance a halogen bulb can drop more than five volts or nearly half of the applied voltage! But, that 1 Ohm is measurable though ill advised. It is better to read the voltages in the energized circuit and use those voltage readings to determine where the waste resistance is. Low voltage on the hot side means there's something wrong there. But is has to be measure WITH RESPECT TO A KNOWN GOOD GROUND not the return wire on the load, itself. That's because the issue might be on the return side and you can only know that by measuring the return side, also, WITH RESPECT TO A KNOWN GOOD GROUND.
Though it seemed basics electrical concept, I never had clarity until I watch your video. You are a great teacher to make me understand simply of my long unclarity subject. Thanks for your teaching..
Very informative I like it when people speak in plan language and are direct and to the point plus his analogy was very good you don't see enough of that on a lot of these videos I watch thank you
Very similar Theory in the electrician world. Checking difference of potential across fuses can you show you whether a fuse is good or bad in a live circuit. Thanks for the wonderful explanation on the DC circuit. I began my post High School career in the Navy in the DC electronics. I have recently 40 years later, went to HVAC School after working as a plant electrician for about 3 years. DC and AC are somewhat different, same principles all around though. I find being able to troubleshoot effectively to actually be a lot of fun/enjoyment. Solving puzzles in life is the epitome for an autodidact/ polymath like myself. 65 yo and still going strong.
One of the best TH-cam videos I've seen on voltage drop testing. It really gives you the fundamentals of how a voltage drop test works in a simple straightforward manner.
Good instructions here. Well explained. I noticed in one of your videos you had Vince Fischelli speak and I must say I was thrilled to see that your channel seeks out some very high level and highly skilled individuals to speak and share their knowledge with your viewers. I have known Vince for over 20 years and he introduced me to electrical troubleshooting and became a mentor in my career and a great friend. I became an assistant instructor for Vince for a few seminars and to this day I owe everything I know to this great man and amazing teacher. You too sir are a great teacher and your ability to keep things simple is noteworthy. Thanks for sharing sir!
We've all assumed at times that the problem in a circuit is in the positive side or in the switches and components. It is helpful to remember that EVERY part of the circuit, from the positive battery post to the negative post, is equally important and equally vital to the circuits proper operation.
That was a hell of an explanation my man you spoke it in the exact way that I needed to understand it been having a long-standing issue with a 2012 traverse and I am not a mechanic by no means but felt as though it was a ground and you just given me the ability to resolve that theory thank you sir!!!!!
im a diyer and as i listen to you sir, somehow my dim understanding of this topic lessen . And my confidence is higher than before maybe because i know that you are true to your purpose and that is to share the knwledge , so thank you sir . my regret is i should have known you in my teenage years
Thank you sir. I just went through electrical class with a terrible teacher for my job. Failed because he couldn't explain it correctly. My boss sent me this video and now I understand the jargon he was tryin to explain. Thank you, thank you. I will keep at it and now will subscribe to your channel. Keep up the amazing work.😊
I once had a car with a rear window defroster, in the form of wires across the window, that did not work. Multiple mechanics at three different shops tried to tell me it was fine. They measured 12 volts on the wires, but failed to notice that the voltage did not drop as the wires went across the window. I found the interruption on the ground side of the circuit and fixed it, and the defroster worked fine after that.
This is a very good example of the three test I teach my students. 1. Open circuit voltage (OCV) 2. Available voltage and3. Voltage drops.Very good demonstration.
Think of it this way - voltage is used to push through the resistance in a circuit and the load SHOULD be the major source of resistance. But if there is a THEIF or unwanted source of resistance, it too will want its share. In this case, excessive resistance in the ground path after the load will demand some voltage of its own. And that is what the meter is telling you...there is another resistance downstream that you have to correct in order for all the voltage to be consumed by the load. Does that help?
Great video. 30+yrs working on vehicles and HVAC for dealerships and companies, as well as myself. Understanding basic ohms law and electricity can be used in all electrical circuits, both A/C and D/C in vehicles, homes, building controls. Thanks again for a great video.
I have been in electronics since I was 18 years old and am 69 now and want to thank you for presenting this. You did not need to get real technical just show the results. If someone watches this and looks at a water hose they can very well understand it. In the hose, pressure = voltage, water = current and pinching the hose is resistance. Pinch the hose and the pressure before the resistance increases, current then decreases. If the water (current) can’t flow you still have pressure, voltage and the resistance, pinched hose has increased. Good job.
I have seen this technique before in another of your chapters and it really helped me to understand the concept which in turn made my diagnosis a lot easier and fun it's allways good to see it again so little details won't de over looked, thank you for been so generous and sharing your great knowledge keep up the great work.
Incredibly helpful and explained with amazing clarity. Thank you so much for these videos! The wiring diagram vids and these have helped me understand so much better than any other material I've found so far!
Videos like this are invaluable. A few years ago, I knew nothing about automotive electrical troubleshooting. Although, I understood electrical circuit fundamentals, automotive circuits seemed extremely complex and overwhelming. However, each time I faced a new problem and searched for specific solutions, I found fundamental videos about electrical troubleshooting to be the most beneficial. Now I approach problems more strategically by studying electrical circuits for the specific vehicle and then going through the testing process until the problem is found.
First thing to check is that you have a good, solid, clean earth strap from the battery negative terminal to the chassis. Corrosion at the chassis can leach a voltage and give you a reading.
Exactly! A friend with an old rust bucket truck couldn't get the motor to start, yesterday. The battery was new, but the frame and body is solid rust . I suggested cleaning all the ground straps from the engine, body, and frame. Nope. He suggested that another guy push start the truck with a skid steer!
I am a journeyman lineman, a journeyman meterman, a relay tech and a retired protection and control foreman and I learned a lot. Fantastic video. I had never seen this before. He used different terminology which was great.
Dude I loved the video and learned even though I thought I knew not everything but all the interesting things. Point Being could you have shown the short or where the resistance was that was evident in the beginning of the video? I would have loved to see what was causing your showing of about 8-9 volts on the negative side of the battery.
Amazing explanation! I never had this insight before and it makes perfect sense the way you explain it. Thank you. I will dig into the rest of your series.
thanks for your teaching skills and making it very understanding for most people that have a hard time at electronics or new to the automotive business.
As a 20 year foreign car mechanic I can tell you from experience grounding problems are the first thing you need to examine when you have electrical issues or anomalies
Larry, one thing not covered in this video......a crusty moustache is not an indicator of a clean man. Good grounds or bad in a car, if the owner has a crusty moustache then he is generally not very well kept and requires a wash
I just watched the Schrodinger's Box video on voltage drop yesterday and this video was an excellent complimentary video to it. There is SO much to learn about cars (especially when it comes to electrical) besides just turning wrenches. 🔧 I love videos like this that cover things beyond basic repair videos. I want to see more videos like this.
I taught electronics in the military and civilian sectors and, though you may know what you're wishing to convey, they way you convey it is convoluted and confusing. Even your mockup with the two bulbs as resistances in a circuit is confusing because you have another black line representing a circuit path shorting the "unwanted resistance." Why would you do this to people who are already struggling to understand what you're trying to convey? The fact that you call the red lead of the DMM the "positive lead" and the black lead the "negative lead" shows a fundamental misunderstanding of how to use a DMM. The black lead is the REFERENCE lead and the red lead is the MEASUREMENT lead. Your meter doesn't even label them positive and negative! There are systems that are positive ground where the reference lead will be on the most positive side of the power source. Telecommunication DC plants are like this and are -48VDC, typically. When you see a measurement, the reading is IN REFERENCE to the black lead and it may be positive or negative but you know it is WITH RESPECT to the reference lead. Telling people that "voltage is consumed" by a load is also just confusing since there is no physical way to demonstrate this. It's just as easy to teach electrical fundamentals CORRECTLY as it is to BS your way through it. I'm a retired engineer/teacher and what you did in these 9+ minutes is just cringe. Telling people to remember adages instead of explaining the "why" of it only makes things easier on YOU, not on the pupil. SMH Awful. Just awful. THIS is why people think electronics and/or math is difficult... they think if they don't understand something it's because they're just not getting it when, in fact, it is the horrendous teaching abilities of the person in from of them.
@@DiffEQ That's funny, I was never confused watching this video. Maybe your way would actually be more confusing to the newbie. This was the simplest way I've seen to identify, and CORRECT electrical problems in automobiles. I've been working on them for 50 odd years, and was a certified A.S.E. mechanic. Sometimes the correct engineering nomenclature is more confusing than a simplified basic explanation. Go get a life!
Fantastic. Not enough of this type of presentation and teaching out there on the topic at hand. Making something that, in my head, is chaotic and complicated, into something simple and smooth. Subscribed. Gonna share it too. Thank you
Hi Pete thanks again for the video,you are certainly blessed with a great way of explaining things,when I started off as a tech I couldn't get my head round the systems just by overcomplicating them,so many thanks to people like yourself and Paul Danner I have a much better understanding and far more confidence in my work,thanks again 👍👍
God bless him? How in the world did you get ANY understanding of how voltage and resistance relates when he use verbiage like "consumes the voltage?" ??? This is an example of hand-waving and not caring about teaching fundamentals at all... which is easier, but you have to know it yourself, first!
Nice video! I'm a master electrician and i know ohms law inside and out but i thought you did a great job of boiling it down to a very practical and useful chunk. Cheers
That's laughable. I was a journeyman and went to engineering school. I know you don't know ohm's law inside and out. You think you do. I thought I did too. Until I went to engineering school and learned how much I didn't know.
@@Impedancenetwork your right. Electro magnetic theory goes beyond my firm grasp. However i repair motors and generators so i have a good working knowledge of impedance (inductive/ capacitive reactance + liniar resistance). My point was not to brag but to complement the host and add weight by mentioning my background. I hope you do more with your education than laugh at people beneath you on you tube.
@@simclardy1 im a master electrician for 15 years, been in the field for 25 and have an associatesl degree in electrical technology. I have worked with countless EE over the years and I am amazed at what some of them dont know. I had a couple coming to me for help when they were studying for the PE exam. Its frustrating when a so called professional thinks we have nothing to offer or scoff at our opinion because we dont have a couple letters behind our name. I know that most EE have vast knowledge in theory and can be great resources and i look forward to working with most. I wish that some would quit looking at us like were just wire pullers and pipe benders. Some of us have extensive background in electrical theory, design and installation. OK, getting off my soap box.
@@farmerjim-fat-man-do thank you. I could have worded my original comment better but i agree with everything you say. I have friends who are amazing electrical engineers that design all kinds of cool things....so, much respect, but like you said it's not a given just because you have a title.
To all in this thread. Two of the same cables that is 3 feet and 100 feet and have the same current through each of them will become equally warm on their insulation regardless of length.
Great explanation. Taught very well. The most complex lessons taught in simplicity means you know the topic beautifully. Learned all this as a kid the hard way and you explained it much better. Great job. I still hate electrical lol.
100% best way to check for high resistance in a circuit. I've seen guys do voltage drops test and think that seeing 0vs means there is an open then do drop test across an open then spend days wondering where the short to voltage on the ground side is. There is no short to voltage it would be fucking impossible to have a short to voltage on the ground side without a blown fuse or a wire lighting a car on fire.
This is good stuff! I'm working on a degree in electronics but I want to be able to diagnose electrical problems in my cars. It's almost impossible to find someone in our area that can do this. The ones who can charge really high prices. Im beginning to understand why.
Good stuff? I beg to differ. Ever wonder why so few people grasp these simple things? Bad instructors. I taught electronics in the military and civilian sectors and, though you may know what you're wishing to convey, they way you convey it is convoluted and confusing. Even your mockup with the two bulbs as resistances in a circuit is confusing because you have another black line representing a circuit path shorting the "unwanted resistance." Why would you do this to people who are already struggling to understand what you're trying to convey? The fact that you call the red lead of the DMM the "positive lead" and the black lead the "negative lead" shows a fundamental misunderstanding of how to use a DMM. The black lead is the REFERENCE lead and the red lead is the MEASUREMENT lead. Your meter doesn't even label them positive and negative! There are systems that are positive ground where the reference lead will be on the most positive side of the power source. Telecommunication DC plants are like this and are -48VDC, typically. When you see a measurement, the reading is IN REFERENCE to the black lead and it may be positive or negative but you know it is WITH RESPECT to the reference lead. Telling people that "voltage is consumed" by a load is also just confusing since there is no physical way to demonstrate this. It's just as easy to teach electrical fundamentals CORRECTLY as it is to BS your way through it. I'm a retired engineer/teacher and what you did in these 9+ minutes is just cringe. Telling people to remember adages instead of explaining the "why" of it only makes things easier on YOU, not on the pupil. SMH Awful. Just awful. THIS is why people think electronics and/or math is difficult... they think if they don't understand something it's because they're just not getting it when, in fact, it is the horrendous teaching abilities of the person in from of them.
I am a retired electrician electronic technician. After retiring, I went back to school and got an associate degree in each. I also taught up until covid. An excellent presentation. If I might make a suggestion, a quick removing, cleaning, then reattaching the ground cable, and then remeasureing would validate the lesson. Thank you.
Thank you for showing us this method of diagnosis. I have a cherokee that every time I turn on the blower fan the voltage will drop from 13.4 to 12.5 I used this technique to determine that the blower fan was at the end of its life and had too much resistance. Must people think that it's the blower resistor and change it with no affects on the problem. Replaced the fan motor and no more voltage drop.
Outstanding video, thank you from Montréal. I bought an old German car recently for fun DIY, and a multimeter, and will go through your series here before spending a day just measuring and trying to diagnose with the kids. Thanks for adding a little joy to the world.
Always place the fuse on the POSITIVE SIDE of the circuit. That's a good point to analyze and a valuable lesson to remember - and it will go a long way. Thank you for the informative video. Keep it up, Sir.
that is not necessarily true it may be good practice but it can be placed anywhere in the circuit and still work if the circuit is fused for over amperage. if you want to protect from short circuits it needs to be as close to the source as possible
The best thing to do is test the battery cables. Make sure the connections are clean because if there isn't a solid connection then you will see a voltage drop from either cable or both. Take your volt meter probes and apply one to the the end of the negative cable chassis lug and the other lead to the actual chassis some where near but at another point. If it is not a solid connection the you will see voltage. That is what is called a voltage drop, Voltage drops are bad connections with enough resistance to show as voltage drops across that bad connection. You can use this method to test all suspected connections. This includes the battery positive post cable to alternator connection. also check the resistance of each cable disconnected from the battery, it should read way less than 1 ohm.
That's a nice explanation! As an electrical engineer it's clear to me what you are doing, but I don't think I would have thought of this method for troubleshooting ground faults in my car. A nice method to add to my toolbox, thanks!
Knowledge is the key to freedom and financial security, thanks for taking the time to educate it is worth more then all the welfare checks ever given !
Yep, absolutely true. A number of years ago, I was given a old car by a friend that just wanted to get rid of it. One headlight was full brightness, but one was very dim, and I couldn’t tell the diff between high and low beams. He told me that no one had been able to locate the problem. I traced the problem to a corroded ground wire on the dim headlight. The current was finding its ground path through the other filament, then to the other headlight through the wiring. I added a separate ground wire to the circuit on the dim side… worked perfectly!
Heads up: In a circuit, let’s say a light bulb or electric motor, if you unplug the ground side and test it, you WILL get voltage on that ground side. Voltage still flows through the filament or motor windings. Keep this in mind when diagnosing.
I'm almost certain that is not true. If you still get voltage, something is on somewhere. Modern cars almost always have a some sort of computer, that'll stay on for 15-20min after the car is off(usually pulls .300-.800 volts) . If it's a higher end vehicle, they usually always have a computer on, which is why the battery dies after a couple weeks of it not being started.
Blackhawk 7r I believe you are right about measuring current on the negative side of filament , current flows all the way to the end of a circuit even if the end of that circute is the neg. side of a filament . the reason the lightbulb does not light is because the current is static and not flowing , their is no continuous flow of current. That given that the switch is on , if the switch is off then current stops at the switch .
Absolute gold....I have and old Jeep and JCB backhoe I am always messing around and this just popped up in my video feed. Exactly what I needed, thank-you for the great content. Subscribed.
Great video, now I know why I'm always getting electrocuted, I know next to nothing about electricity and I'm 71, worked on many a vehicles but wiring not my cup of tea just do not understand it no matter how simple you put it. Liked and subscribed, hopefully you can teach an old dog some new tricks.
High resistance in your ground circuit. Poor connection or possible battery cable issue. Ideally the circuit needs to be under load. Turn headlights on would be a good load. Without having the circuit under load you will get an inaccurate reading
I appreciate all the comments and critiques! This is an older video that I learned a lot from, and I've since tried a few different ways of explaining ground side voltage drop. I hope you will all sub to our channel and check out the entire "Trainer" library. THANKS!
Motor Age This is by far the BEST way I’ve ever heard it explained. No one EVER really explained what and why your car’s chassis is used as ground! So simple, but a lot of people may not know that!
Like and subd, thanks,
yeah! your stuff exposes much that is missing in the understanding of automotive and electrical control.
I am critical(constructively) but I appreciate your work.
...and I am subscribed...
..
I will be referring your efforts to a few classes of grade six's as I do lectures on their Flight then Electricity portions of their curriculum. Very well done video! The half split method demo'd is crucial in troubleshooting 👏
I am 59yrs old and you are the 1st to explain this to me where this makes sense.. Thank you for your knowledge and videos USA 🇺🇸 USA 🇺🇸
As a Mechanic of 40 years and Shop owner I’d like to Thank You. This type of video training is desperately needed, it never ceases to amaze me how many mechanics come through my shop and are absolutely Clueless about electrical basics but claim to be diagnostic Techs... now, with these videos I can educate my trainees without going broke
That's great! Glad you and your team find it helpful. That's what we do at @MotorAgeMagazine - "advancing the automotive service professional" since 1899.
Makes a fella wonder if scientists today could operate a slide rule in case our chinese pals launched a EMP and shredded computer networks. They may have changed this because it made sense (we can't have that). The Navy uses all manner of hi tech technology but they still train Quartermasters to navigate the same way Columbus did. It's like banning calculators from math class.
I experienced the same issue when I owned my shop th-cam.com/video/DA4vl2CsMSY/w-d-xo.html when I would get other shops referring a customer over for a problem they couldn't figure out and it would often turn out to be a failure of basic battery or charging system testing 🤦🏼♂️
I've been a DIY for a few years now, gaining much more confidence. The sad part is, in my area. You need to have your certifications complete to even be considered. (my experience does not apply to all shops and areas/city/states).
I have high aptitude for electrical, and not mechanical since i've DIY put many parts in my own vehicles.
This is a great video, to be honest, you really do need to practice practice practice. There's no replacement for learning the basics through trial and error.
Other day i was testing a starter, before realizing.. (duh), i need lower AWG conductor that can handle the voltage and current to run the motor. Used some jumpers, BAM.. power. Another tip for future technicians, it's NEVER too late to learn the basics.
I tell my kids the same. It's like try to use your left hand as much as you can, even tight a shoe, drinking coffee, you never know, when it will be the only hand left to use it. And you mentioned sliding ruler, about a cashier or bank clerk, figuring out how much change is due back to a customer? 🤣🤣. AI will not longer work also, but God
Trainer, You Sir, are a true Teacher!
Out of my 65 years on this earth, I've never heard of anyone explaining a "Voltage Drop Test" in such a Pure and Simple too the point presentation. You take the saying of "Explain it too me like I was 9 year old" too a whole other level.
Great Job mister!
Thank you! I'm glad you found it helpful.
To!
75 yrs old. 37yrs@ AT&T. 4 yrs in Harley independent shop repair. Thank you for your knowledge.
I have a degree in automotive science and I've been certified twice as a master auto technician and I'm impressed with this gentleman's approach to teaching these concepts.
I am so very glad that you said the “Fuse” is their to protect the wiring. Although explaing why it’s on the positive side was a nice touch, but while the component is designed to be changed, the wiring harness is not. Depending on where you grew up and how, like a farm, there where not a lot to trade schools near by to attend to learn automotive mechanics. The high school did not even offer it or woodworking. But, I asked questions, watched others and most importantly did my own work. Having my cousins bring an old school, rope wound go cart to the farm for use 3 months of the year, was the one thing I feel in love with. Wheels, going fast and the freedom, but it quit. It was a huge incentive to learn how to diagnose a small gas engine, basically graduating from taking two lawn mowers and making one run. Considering we did not get an allowance, a gas engine make earning that $1 per yard easier. Fixed the go-cart and was saved from the butt-kicking I would get from my older and bigger cousins next summer. Being an apprentice in a one man shop is still possible but more rare with the complexity of systems. As paper factory service manuals where normal, few of us still remember the back page with the schematic for the vehicle and it’s variations where found. Yes, they folded out 8, 10 or 12 pages but the head light where on the left or first page, while the tag, tail and stop lights where on the last page or right. Everything else in the vehicle was in the middle with no rectangular boxes that said “Logic” inside. Best of all, no two techs having the same talents they put descriptions of voltage drop and other meaningful information in the beginning of that section. You could walk into a dealer, line up 20 techs and ask to describe voltage drop and only one or two hands at best would go up. Not much better today but I found it to be the easiest, quickest and it never lyes. Best of all, you did not disturbed the other wires, connectors or terminals, in case it was an intermittent problem that was acting up for four days straight. Working at a Buick, try explaining to a 70 to 80 year old man why the radio, windows, wipers or sunroof worked, with the key off, then quit when you opened the door! It was a short I tell you! No, read page 66 of the owners manual under features. Thanks for the wonderful and good video! ASE Master Tech since 1978 - Retired
Voltage drop was a life-changer as a dealer tech. Every new tech needs this video as a primer to step into the shop. You are are a gentleman and a scholar, and even more, you are a teacher among teachers, sir.
Thank you
You have got to be kidding.
I taught electronics in the military and civilian sectors and, though you may know what you're wishing to convey, they way you convey it is convoluted and confusing. Even your mockup with the two bulbs as resistances in a circuit is confusing because you have another black line representing a circuit path shorting the "unwanted resistance." Why would you do this to people who are already struggling to understand what you're trying to convey? The fact that you call the red lead of the DMM the "positive lead" and the black lead the "negative lead" shows a fundamental misunderstanding of how to use a DMM. The black lead is the REFERENCE lead and the red lead is the MEASUREMENT lead. There are systems that are positive ground where the reference lead will be on the most positive side of the power source. Telecommunication DC plants are like this and are -48VDC, typically. When you see a measurement, the reading is IN REFERENCE to the black lead and it may be positive or negative but you know it is WITH RESPECT to the reference lead.
Telling people that "voltage is consumed" by a load is also just confusing since there is no physical way to demonstrate this. It's just as easy to teach electrical fundamentals CORRECTLY as it is to BS your way through it. I'm a retired engineer/teacher and what you did in these 9+ minutes is just cringe. Telling people to remember adages instead of explaining the "why" of it only makes things easier on YOU, not on the pupil. SMH Awful. Just awful. THIS is why people think electronics and/or math is difficult... they think if they don't understand something it's because they're just not getting it when, in fact, it is the horrendous teaching abilities of the person in from of them.
@@DiffEQin the automotive world, nearly everything is 12 volt D.C. negative ground. The only thing I’ve ever seen with a positive ground is a Ford tractor from the 1950s that was 6 volt.
@@DiffEQ so where is your video to train people properly?
@@DiffEQ Please direct us to your video on this topic so that we can learn something. I see that some other people have made the same request, so please edumacate us!
Thanks for taking time out of your day to help people you don't even know. It's nice to be critiqued.
Man, this is an awesome video, and you are a great instructor! No silly, flashy crap; just clear, concise and coherent. I already knew a lot of this information, but I often watch videos on topics about which I am already fairly knowledgeable in order to see if there's a better way or something I've missed in my years of doing this kind of work. So glad I did! Thanks!
When I was 18 ,I had an issue with the frequency valve on a Bosch CIS injection setup.
I had power at the plug ,but it wouldn't operate.
I swapped it out ,same thing.
Haha ,dad ,help!!
He's not an auto tech by any means ,but an engineer and I never recall bringing our cars to the shop.
After 30-40mins ,he found it and it was a broken wire in the harness.
I was amazed because he came into it saying he "didn't know anything about these cars".
Probably part of what made me go to tech school and see if I could learn what he knew.
He always took time to explain it but the formal training was a big help.
As an hvac tech, 20 years in ac, and dc controls, and a gear head too, this is a true refresher and good foundation for newcomers too.
Hi sir
As an HVAC tech, can I ask u for a help with my 2001 MAZDA protege 5?
@@tmanda323 I don't know anything about those particular cars, but what is it doing?
@@jasonmitchell7677 AC works only in 1 speed of fan. In 2, 3 and 4 AC stops but fan keeps runing
Sorry for my bad english writing
@@tmanda323 ... surely you have repaired it by now, or it could ruin the entire thing. Some examples:
- it could be a simple switch and/or wiring issue.
- AC clutch burn out
- compressor overheating( short cycling, lack of external cooling, poor ventilation, low suction pressure, high head pressure, poor lubrication, wear and tear/getting old... that can cause electrical problems)
- A short can ruin the clutch, and a cascade of other things that are mechanically attached, like the belt system, ... weak charging, overworking the alternator, ...
@@DormantIdeasNIQ Thank you sir. Yes I have repaired it.
3 years of engineering at university (and flunking electrical engineering a few times) still failed to help me fully understand what this video clarified in less than 10mins !!!
I'm was an Electrical Engineer earlier in my career and now am a handyman. Funny how the simplest of things can stump someone who should know. Great video!
I'm an engineer (not EE, but I am involved in amateur radio and I fix my own vehicles). FIRST thing I thought was _ground loop_ but some kind of parasitic drain in a car nowadays is almost always going to happen some time or another. It's gotten to the point we have TOO MUCH electronics in cars now.
Stumbled across this video while looking for something else. Voltage drop is such an easy way to diagnose electrical issues and so few people know how to use it. I started in life as an auto tech many years ago but left it behind to become an electrician. I had a crusty ole mechanic show me how to check voltage drop when I was just starting out and actually created the interest in electricity that eventually lead me to leave the auto repair world. i am still heavily involved with classic cars and the go to guy at work when people have car troubles. I can't tell you how many fellow electricians l have had to school on voltage drop and how easy it is to diagnose problems using this technique.
You're correct, figure out what voltage drop Is, how to measure it and what the meter is telling you and electrical problems will no longer be a problem.
Thanks for sharing the video.
Great story! If that crusty old mechanic is still alive, maybe you can let him know how much he did for you. Although, I’m guessing you already have.
Cheers
EXCELLENT !!!
Basic, simple principle, misunderstood by 95%.of mechanics.
HotRod Ray my son is an auto tech at a dealership. I told him before he went to tech school, if he would learn only the electrical side of automotive work, he would always be in demand as a tech. So few understand the principals, but 99% think they know everything about it! That 1% that know they do not understand everything about that electrical system are the ones that best understand those systems!
yes, but not by real technicians.
So many people forget that water runs up hill.
Some mechanics with a car that is totally dead with a good battery will tell you the electrical system is fried or some other word indicating you cars electrical system has gone out like a watch or radio or cell phone that has bricked. It indicates he does not know electrical very well and therefore he is going to start swapping part, probably starting with the expensive computer an hopes he get lucky. That is why you know how to use a diagnostic plug and know the computer is involved if the plug does not work. Unfortunately at that point you probably need an electrical diagram to check the voltages on the plug going into the computer and some advanced electrical components to do that while it is plugged in like a probe that penetrates the wires.
That's why they are mechanics and not auto electricians
This video was great it will help me understand a lot when I’m troubleshooting my own vehicle problems on my vehicle
Great explanation, you made it so simple to understand. Keep up the great work! 👍
I've been a mechanic for quite a while and have worked in several shops but really never learned the electrical aspect of it because like probably a lot of shops we had a go to guy because I think that is pretty common in shops. anyway I got out of the business around 2003 and now want to get back in to working on cars but instead of just getting by I want to under stand the electrical system as good as I can. I like your down to earth teaching style and I am starting to learn on my journey back into the business . Thank you for your sacrifice.
"Down to earth teaching style" Too funny.
If I had a friend, I would definitely share this! (Been messing with cars and machinery for 2/3rds of my life...but I can still learn something from a great basic instructional like this. The model circuit used for illustration really hits a home run!)
I read the title and instantly knew what was coming. It's a very basic principle that too many greenhorns overlook. I watched a guy change a fuel pump three times before I took over and found that the customer had disconnected the ground for that circuit so he could install a boom box in his trunk. It's not enough to know that something isn't working, you have to know why.
@Yard Sale Dale - I'm sure that was exactly what the supervisor asked him. I wasn't there for that conversation. Was it a lack of know how or imagination? Your guess is as good as mine.
I have an electrical engineering degree but don't know where to start with car electrical because I do not have a schematic and have know what explain the basics of a schematic (if I had on) to me. I watch these and other people explaining electrical problems because these are very expensive repairs I could do myself and can be useful when electrical problems strand you on a trip. This video basically says always check both sides of a load to the body, because in many of the repair videos the pathway to one side or the other (+ or -) is compromised. Someone did a video of checking the computers harness to verify the computer is the problem and not the harness voltages. Another is the battery, wiring/fuses, solenoid, or starter the problem by looking a voltages while attempting to start the car. Knowing how to use a diagnostic plug to take a first pass at a problem is also useful.
I changed my head gasket went to start truck . Starter burnt out . I fixed it went to start truck . No fuel. Pump not running. Well I just got pump off. Is there anyway I unhooked a wire some where. Or is it my fuel pump. I went from head gasket to waterpump it started for a second . Shut off just was checking time before fan and stuff so maybe enough gas to barely start idk. But after together and starter issue . No gas pressure no noise from tank. And I wasn't pulling bed off I took tank down. If anything I'm going to try run wire to pump. Just cold out now. And if ain't pump on Ford ranger maybe u might have idea. Ty if u read this
@@gordontrainer3546 is the ground cable from the battery connected to the engine block?
And is the ground strap from the head connected to the cars body?
The body/chassis ground engine ground, are the sources the other grounds use for a path to the negative battery post.
Sometimes people don't put things back or put them back differently because they aren't somebody who does that work with repetition.
Did you take anything else apart?
Are the connections in good repair and not corroded?
Retrace your steps inspecting what you had to do and if you can't find something, diagnose the fuel pumps operation as per the service manual.
You can get literature free on library databases from home using a library card.
Some data bases, you go to a library for access. Print your pages and return.
That's what I do if I need familiarity and a map and procedure.
A fuel pump uses an inertia switch as a shut off for safety. It uses a fuel pump relay.
It is turned on and off by a PCM.
The PCM must have signal spark is working or it can shut fuel pressure down for safety.
This is why having service manuals can help, knowing how the circuit works and what components are included in the circuit.
Fuel delivery can be shut down as well by antitheft .
You know you are working with pressure loss of supply because you don't hear the pump run.
Stick to why that is first, as you probably know.
But only you know what change could be likely to have been caused, since it worked before you began.
Locations of components is also info service manuals provide.
A good portion of what they publish is correct.
A small portion needs updating or correcting to be less vague.
You said it seemed to run for a second. This could be a clue it can run but is being interrupted.
You write some phrases that raise more questions. I won't be able to go back and forth. You can do that with an online tech assistance and read other people's fixes for their circumstances.
They made Rangers for a great number of years. Always refer to year/make/model, engine size, trans type, unusual options.
Then the helper can picture what components and systems are in use on yours and particular info to yours.
Good luck.
This tape will self destruct in 5 seconds.
@@gordontrainer3546 You just took the car apart and now you don't have fuel pressure. The very first thing is to double check your work. Many computers are designed so that if a crucial sensor is giving a signal that would indicate the engine shouldn't be running, the computer will cut fuel or ignition. A disconnected or damaged sensor can trigger this. So, check to make sure everything is plugged in and undamaged. That includes the wires that carry the signals. Did you check the fuel pump fuse? Did you check for power at the fuse? Did you check for power and signal at the relay? Did you try swapping a known good relay in, to test the relay? Did you check for power at the tank? Did you check for ground at the tank? All of these tests should be run before removing the tank and the pump. There are no returns on electrical parts. Running a raw wire to the fuel pump is a recipe for disaster.
Pete, I just recently "stumbled" across your video series while in the process of looking for something else. I've watched a handful of them on electricity and electrical diagnosis, and I'm impressed with your skill as an instructor. You clearly know how to share what can be a challenging subject in a manner that is readily understandable. In this video, I particularly appreciated your taking the time (at 2:20) to explain why the circuit protection device is always placed on the positive side of the circuit. I would add that this device should always be placed as close to the battery's positive terminal post as possible, the reason being that it increases the likelihood that the device would still be included in the circuit in the event of a short circuit prior to the load.
Thank you for such an explanation. Takes away my fear from electrical problems.God Bless you.
Hey thank you!!!!!!! You explained it better than anyone else on here. I'm working on a 1988 Ford F250 diesel with the glow plugs not firing and a voltage drop.I'm not a professional mechanic and It's in my driveway currently, Now I know where and how to start troubleshooting it. THANKS A MILLION!!!!!
Hey Pete. I hope you're still around. I just found these and want to thank you for a well produced and simply explained series. I know all of this stuff but have been looking for links to send the many people who ask me for advice. These are so well done and explained. They are a great resource!!
this video is a definite part of my level up. i've had about 8v on my chasis, measuring from the negative post and i've been racking my brain how that could be. now i know. thank you Sir!
but also, what if i disconnect the positive terminal from the battery, and i measure voltage from neg post (disconnected) to chasis ground. internal short of battery?
Good stuff. High resistance in the positive side of the circuit leads to this situation: The lamp won't light. Re-lamp no help. We know that the lamp will operate when we connect +12 volts on one terminal, and a ground on the other. We remove the lamp, measure 12 volts on one terminal and a good ground on the other. We reinstall the lamp, it still does not light. What did we miss? We know the ground is good because we measured it with an ohmmeter. We assumed the positive (power) side is good because we measured full battery voltage on it. BUT, we had to remove the lamp, which is the load in the circuit, to put the positive meter lead on the terminal in the socket. We have now replaced the normal load, which draws a current of, say, half an amp, with the meter, which draws a current of--guess what--practically zero amps. Voltmeters have very high internal resistance, typically in the millions of ohms. If you have a corroded or damaged connection or wire on the positive side of the circuit, even if adds thousands of ohms of resistance, the tiny current drawn by the meter will not cause a noticeable voltage drop in your measurement. So you measure twelve volts at the terminal with the lamp removed, but when you replace the lamp in the socket, any current it draws will cause most or all of the voltage to be dropped across the high resistance of the fault. The voltage you thought you had measured disappears the instant the normal load is inserted into the circuit. This is why you always attempt to make your voltage measurements in a complete circuit, with the load connected and any switches turned on.
You cannot measure the return with an Ohm meter and call it good. That's the problem with hack teachers like this guy.... they don't really explain anything and make up things like "consumes the voltage." Absurd.
Not all things are Ohmic. Incandescent filaments are a prime example... measured with an Ohm meter you will get nearly a direct short (depending on the bulb Wattage and voltage rating). You know that can't be. What happens is that the filament has a positive temperature coefficient and the resistance rise as it heats up.
Your claim that a multimeter will not measure thousands of Ohms of resistance because the current is too low is grossly incorrect. Even at just 1 Ohms of resistance a halogen bulb can drop more than five volts or nearly half of the applied voltage! But, that 1 Ohm is measurable though ill advised. It is better to read the voltages in the energized circuit and use those voltage readings to determine where the waste resistance is. Low voltage on the hot side means there's something wrong there. But is has to be measure WITH RESPECT TO A KNOWN GOOD GROUND not the return wire on the load, itself. That's because the issue might be on the return side and you can only know that by measuring the return side, also, WITH RESPECT TO A KNOWN GOOD GROUND.
Though it seemed basics electrical concept, I never had clarity until I watch your video. You are a great teacher to make me understand simply of my long unclarity subject. Thanks for your teaching..
Very informative I like it when people speak in plan language and are direct and to the point plus his analogy was very good you don't see enough of that on a lot of these videos I watch thank you
For beginners, I think it is the most simple and explicatory introduction to vehicle electrical basis . Thank you very much for the lesson.
Excellent demonstration. Most of the techs I work with don't know basic electrical physics and can't perform a correct diag.
Thank you for the video.
Very similar Theory in the electrician world. Checking difference of potential across fuses can you show you whether a fuse is good or bad in a live circuit. Thanks for the wonderful explanation on the DC circuit. I began my post High School career in the Navy in the DC electronics. I have recently 40 years later, went to HVAC School after working as a plant electrician for about 3 years. DC and AC are somewhat different, same principles all around though. I find being able to troubleshoot effectively to actually be a lot of fun/enjoyment. Solving puzzles in life is the epitome for an autodidact/ polymath like myself. 65 yo and still going strong.
Excellent. well prepared, No fumbling of leads, glaring bulbs, no distractions. You demonstrated this perfectly.
+daveS ministry Thank you for your kind words. We're glad you liked it!
Motor Age
One of the best TH-cam videos I've seen on voltage drop testing. It really gives you the fundamentals of how a voltage drop test works in a simple straightforward manner.
Good instructions here. Well explained. I noticed in one of your videos you had Vince Fischelli speak and I must say I was thrilled to see that your channel seeks out some very high level and highly skilled individuals to speak and share their knowledge with your viewers. I have known Vince for over 20 years and he introduced me to electrical troubleshooting and became a mentor in my career and a great friend. I became an assistant instructor for Vince for a few seminars and to this day I owe everything I know to this great man and amazing teacher. You too sir are a great teacher and your ability to keep things simple is noteworthy. Thanks for sharing sir!
I don’t know how this video came in my feed, but glad it did. So easy to understand and apply this knowledge. Thank you sir for sharing the knowledge
Thanks for all of your trainer videos. Straight-forward-to the point.
Thank you for taking time out to make videos for the public, I certainly appreciate it myself. I always come back to your vids. to refresh my memory..
From someone with a couple of years in electronics, you did a phenomenal presentation of an interesting subject. I thank you Sir! I also subscribed.
Thank you..
We've all assumed at times that the problem in a circuit is in the positive side or in the switches and components. It is helpful to remember that EVERY part of the circuit, from the positive battery post to the negative post, is equally important and equally vital to the circuits proper operation.
That was a hell of an explanation my man you spoke it in the exact way that I needed to understand it been having a long-standing issue with a 2012 traverse and I am not a mechanic by no means but felt as though it was a ground and you just given me the ability to resolve that theory thank you sir!!!!!
im a diyer and as i listen to you sir, somehow my dim understanding of this topic lessen . And my confidence is higher than before maybe because i know that you are true to your purpose and that is to share the knwledge , so thank you sir . my regret is i should have known you in my teenage years
Thank you!
my pleasure sir!
Thank you sir. I just went through electrical class with a terrible teacher for my job. Failed because he couldn't explain it correctly. My boss sent me this video and now I understand the jargon he was tryin to explain. Thank you, thank you. I will keep at it and now will subscribe to your channel. Keep up the amazing work.😊
I once had a car with a rear window defroster, in the form of wires across the window, that did not work. Multiple mechanics at three different shops tried to tell me it was fine. They measured 12 volts on the wires, but failed to notice that the voltage did not drop as the wires went across the window. I found the interruption on the ground side of the circuit and fixed it, and the defroster worked fine after that.
This is a very good example of the three test I teach my students. 1. Open circuit voltage (OCV) 2. Available voltage and3. Voltage drops.Very good demonstration.
+Roddy Rampersad Thanks for sharing your comments.
Roddy Rampersad How is there electron flow back to the battery ground post if the load consumes all the voltage.
Think of it this way - voltage is used to push through the resistance in a circuit and the load SHOULD be the major source of resistance. But if there is a THEIF or unwanted source of resistance, it too will want its share. In this case, excessive resistance in the ground path after the load will demand some voltage of its own. And that is what the meter is telling you...there is another resistance downstream that you have to correct in order for all the voltage to be consumed by the load. Does that help?
Thanks for the video. Three years after posting it and the video is still helping to educate people like myself.
Glad you found it helpful!
Great video. 30+yrs working on vehicles and HVAC for dealerships and companies, as well as myself. Understanding basic ohms law and electricity can be used in all electrical circuits, both A/C and D/C in vehicles, homes, building controls. Thanks again for a great video.
Brushing up on the basics is always good
,great video thanks
I have been in electronics since I was 18 years old and am 69 now and want to thank you for presenting this. You did not need to get real technical just show the results. If someone watches this and looks at a water hose they can very well understand it. In the hose, pressure = voltage, water = current and pinching the hose is resistance. Pinch the hose and the pressure before the resistance increases, current then decreases. If the water (current) can’t flow you still have pressure, voltage and the resistance, pinched hose has increased.
Good job.
Thank you
I have seen this technique before in another of your chapters and it really helped me to understand the concept which in turn made my diagnosis a lot easier and fun it's allways good to see it again so little details won't de over looked, thank you for been so generous and sharing your great knowledge keep up the great work.
For most of us this remedial , but it is always good to refresh your knowledge, very well done👍
Incredibly helpful and explained with amazing clarity. Thank you so much for these videos! The wiring diagram vids and these have helped me understand so much better than any other material I've found so far!
Videos like this are invaluable. A few years ago, I knew nothing about automotive electrical troubleshooting. Although, I understood electrical circuit fundamentals, automotive circuits seemed extremely complex and overwhelming. However, each time I faced a new problem and searched for specific solutions, I found fundamental videos about electrical troubleshooting to be the most beneficial. Now I approach problems more strategically by studying electrical circuits for the specific vehicle and then going through the testing process until the problem is found.
Which is what a professional does!
First thing to check is that you have a good, solid, clean earth strap from the battery negative terminal to the chassis. Corrosion at the chassis can leach a voltage and give you a reading.
Exactly! A friend with an old rust bucket truck couldn't get the motor to start, yesterday. The battery was new, but the frame and body is solid rust . I suggested cleaning all the ground straps from the engine, body, and frame. Nope. He suggested that another guy push start the truck with a skid steer!
I am a journeyman lineman, a journeyman meterman, a relay tech and a retired protection and control foreman and I learned a lot. Fantastic video. I had never seen this before. He used different terminology which was great.
Dude I loved the video and learned even though I thought I knew not everything but all the interesting things. Point Being could you have shown the short or where the resistance was that was evident in the beginning of the video? I would have loved to see what was causing your showing of about 8-9 volts on the negative side of the battery.
I’ve been looking for this explanation for a couple hours and this is the only one I found and it’s a great video, makes it easy to understand!
Hi Mr. Pete
Thank you for your great help in teaching us about voltage drop
Im your number one fan ...
Keep up the wonderful job .
Amazing explanation! I never had this insight before and it makes perfect sense the way you explain it. Thank you. I will dig into the rest of your series.
thanks for your teaching skills and making it very understanding for most people that have a hard time at electronics or new to the automotive business.
As a 20 year foreign car mechanic I can tell you from experience grounding problems are the first thing you need to examine when you have electrical issues or anomalies
Thank you sir! Great refresher on the basics. May the LORD bless you abundantly!
Is your magical friend taking requests? Prophet, heal thyself.
Thank you for this. I am truly happy to find this information. I want to be the "go to guy" and now I'm on my way!! Thanks again.
Larry, one thing not covered in this video......a crusty moustache is not an indicator of a clean man. Good grounds or bad in a car, if the owner has a crusty moustache then he is generally not very well kept and requires a wash
Excellent demo and explanation. Forget ohm test, thats only helpful for an open, this is the meat, well done sir.
I just watched the Schrodinger's Box video on voltage drop yesterday and this video was an excellent complimentary video to it.
There is SO much to learn about cars (especially when it comes to electrical) besides just turning wrenches. 🔧
I love videos like this that cover things beyond basic repair videos. I want to see more videos like this.
Check out our libraries on our channel's home page! I've got plenty to keep you busy.
I taught electronics in the military and civilian sectors and, though you may know what you're wishing to convey, they way you convey it is convoluted and confusing. Even your mockup with the two bulbs as resistances in a circuit is confusing because you have another black line representing a circuit path shorting the "unwanted resistance." Why would you do this to people who are already struggling to understand what you're trying to convey? The fact that you call the red lead of the DMM the "positive lead" and the black lead the "negative lead" shows a fundamental misunderstanding of how to use a DMM. The black lead is the REFERENCE lead and the red lead is the MEASUREMENT lead. Your meter doesn't even label them positive and negative! There are systems that are positive ground where the reference lead will be on the most positive side of the power source. Telecommunication DC plants are like this and are -48VDC, typically. When you see a measurement, the reading is IN REFERENCE to the black lead and it may be positive or negative but you know it is WITH RESPECT to the reference lead.
Telling people that "voltage is consumed" by a load is also just confusing since there is no physical way to demonstrate this. It's just as easy to teach electrical fundamentals CORRECTLY as it is to BS your way through it. I'm a retired engineer/teacher and what you did in these 9+ minutes is just cringe. Telling people to remember adages instead of explaining the "why" of it only makes things easier on YOU, not on the pupil. SMH Awful. Just awful. THIS is why people think electronics and/or math is difficult... they think if they don't understand something it's because they're just not getting it when, in fact, it is the horrendous teaching abilities of the person in from of them.
@@DiffEQ Do your own video. As a know it all critical person I am sure you can do better than anyone
@@DiffEQ lol what a tool so much education but no intelligence
@@DiffEQ That's funny, I was never confused watching this video. Maybe your way would actually be more confusing to the newbie. This was the simplest way I've seen to identify, and CORRECT electrical problems in automobiles. I've been working on them for 50 odd years, and was a certified A.S.E. mechanic. Sometimes the correct engineering nomenclature is more confusing than a simplified basic explanation. Go get a life!
Fantastic. Not enough of this type of presentation and teaching out there on the topic at hand. Making something that, in my head, is chaotic and complicated, into something simple and smooth. Subscribed. Gonna share it too. Thank you
Hi Pete thanks again for the video,you are certainly blessed with a great way of explaining things,when I started off as a tech I couldn't get my head round the systems just by overcomplicating them,so many thanks to people like yourself and Paul Danner I have a much better understanding and far more confidence in my work,thanks again 👍👍
Outstanding vid! This vid actually opened my eyes on how voltage and resistance relates. God bless you, good sir!
God bless him? How in the world did you get ANY understanding of how voltage and resistance relates when he use verbiage like "consumes the voltage?" ??? This is an example of hand-waving and not caring about teaching fundamentals at all... which is easier, but you have to know it yourself, first!
@@DiffEQ Sorry 😞
Nice video! I'm a master electrician and i know ohms law inside and out but i thought you did a great job of boiling it down to a very practical and useful chunk. Cheers
That's laughable. I was a journeyman and went to engineering school. I know you don't know ohm's law inside and out. You think you do. I thought I did too. Until I went to engineering school and learned how much I didn't know.
@@Impedancenetwork your right. Electro magnetic theory goes beyond my firm grasp. However i repair motors and generators so i have a good working knowledge of impedance (inductive/ capacitive reactance + liniar resistance). My point was not to brag but to complement the host and add weight by mentioning my background. I hope you do more with your education than laugh at people beneath you on you tube.
@@simclardy1 im a master electrician for 15 years, been in the field for 25 and have an associatesl degree in electrical technology. I have worked with countless EE over the years and I am amazed at what some of them dont know. I had a couple coming to me for help when they were studying for the PE exam. Its frustrating when a so called professional thinks we have nothing to offer or scoff at our opinion because we dont have a couple letters behind our name. I know that most EE have vast knowledge in theory and can be great resources and i look forward to working with most. I wish that some would quit looking at us like were just wire pullers and pipe benders. Some of us have extensive background in electrical theory, design and installation. OK, getting off my soap box.
@@farmerjim-fat-man-do thank you. I could have worded my original comment better but i agree with everything you say. I have friends who are amazing electrical engineers that design all kinds of cool things....so, much respect, but like you said it's not a given just because you have a title.
To all in this thread.
Two of the same cables that is 3 feet and 100 feet and have the same current through each of them will become equally warm on their insulation regardless of length.
Great explanation. Taught very well. The most complex lessons taught in simplicity means you know the topic beautifully. Learned all this as a kid the hard way and you explained it much better. Great job. I still hate electrical lol.
Just when you think you know something somebody show you something new thank you sir.
Glad you liked it.
100% best way to check for high resistance in a circuit. I've seen guys do voltage drops test and think that seeing 0vs means there is an open then do drop test across an open then spend days wondering where the short to voltage on the ground side is. There is no short to voltage it would be fucking impossible to have a short to voltage on the ground side without a blown fuse or a wire lighting a car on fire.
I always look forward to "The Trainer" videos. Brilliant series. Thanks Pete.
Best explanation of voltage drop testing I’ve seen yet! The demo you built was invaluable!!!
This is good stuff! I'm working on a degree in electronics but I want to be able to diagnose electrical problems in my cars. It's almost impossible to find someone in our area that can do this. The ones who can charge really high prices. Im beginning to understand why.
Good stuff? I beg to differ. Ever wonder why so few people grasp these simple things? Bad instructors.
I taught electronics in the military and civilian sectors and, though you may know what you're wishing to convey, they way you convey it is convoluted and confusing. Even your mockup with the two bulbs as resistances in a circuit is confusing because you have another black line representing a circuit path shorting the "unwanted resistance." Why would you do this to people who are already struggling to understand what you're trying to convey? The fact that you call the red lead of the DMM the "positive lead" and the black lead the "negative lead" shows a fundamental misunderstanding of how to use a DMM. The black lead is the REFERENCE lead and the red lead is the MEASUREMENT lead. Your meter doesn't even label them positive and negative! There are systems that are positive ground where the reference lead will be on the most positive side of the power source. Telecommunication DC plants are like this and are -48VDC, typically. When you see a measurement, the reading is IN REFERENCE to the black lead and it may be positive or negative but you know it is WITH RESPECT to the reference lead.
Telling people that "voltage is consumed" by a load is also just confusing since there is no physical way to demonstrate this. It's just as easy to teach electrical fundamentals CORRECTLY as it is to BS your way through it. I'm a retired engineer/teacher and what you did in these 9+ minutes is just cringe. Telling people to remember adages instead of explaining the "why" of it only makes things easier on YOU, not on the pupil. SMH Awful. Just awful. THIS is why people think electronics and/or math is difficult... they think if they don't understand something it's because they're just not getting it when, in fact, it is the horrendous teaching abilities of the person in from of them.
Very informative. Thank you for taking the time to make this video. I have learned from it.
Very informative video. I use this method in the Navy troubleshooting electrical systems in aircraft.
I am a retired electrician electronic technician. After retiring, I went back to school and got an associate degree in each. I also taught up until covid. An excellent presentation. If I might make a suggestion, a quick removing, cleaning, then reattaching the ground cable, and then remeasureing would validate the lesson. Thank you.
Very skilled and professional presentation and information, THANK YOU !!
Thank you for showing us this method of diagnosis.
I have a cherokee that every time I turn on the blower fan the voltage will drop from 13.4 to 12.5
I used this technique to determine that the blower fan was at the end of its life and had too much resistance.
Must people think that it's the blower resistor and change it with no affects on the problem.
Replaced the fan motor and no more voltage drop.
Actually your blower had too little reluctance. But that's a subject for a whole other video. 😉
Outstanding video, thank you from Montréal. I bought an old German car recently for fun DIY, and a multimeter, and will go through your series here before spending a day just measuring and trying to diagnose with the kids. Thanks for adding a little joy to the world.
Always place the fuse on the POSITIVE SIDE of the circuit.
That's a good point to analyze and a valuable lesson to remember - and it will go a long way. Thank you for the informative video. Keep it up, Sir.
that is not necessarily true it may be good practice but it can be placed anywhere in the circuit and still work if the circuit is fused for over amperage. if you want to protect from short circuits it needs to be as close to the source as possible
@@richardcranium5839 Thank you. Good info: locate fuse as close to the source as possible.
The best thing to do is test the battery cables. Make sure the connections are clean because if there isn't a solid connection then you will see a voltage drop from either cable or both. Take your volt meter probes and apply one to the the end of the negative cable chassis lug and the other lead to the actual chassis some where near but at another point. If it is not a solid connection the you will see voltage. That is what is called a voltage drop, Voltage drops are bad connections with enough resistance to show as voltage drops across that bad connection. You can use this method to test all suspected connections. This includes the battery positive post cable to alternator connection. also check the resistance of each cable disconnected from the battery, it should read way less than 1 ohm.
good video, I know this but is good to refresh your mind, because sometimes we all forget what we have learned over time.
Amazingly comprehensive video, thank you so much
That's a nice explanation! As an electrical engineer it's clear to me what you are doing, but I don't think I would have thought of this method for troubleshooting ground faults in my car. A nice method to add to my toolbox, thanks!
Excellent information - you took me back to my High School Physics days.
All killer, no filler! Very complete video. Kudos, sir.
Knowledge is the key to freedom and financial security, thanks for taking the time to educate it is worth more then all the welfare checks ever given !
IT tech here, turning into ET tech, learning circuitry and current flow. Thank you. Subscribed.
Pp
I think this is great info. Thanks for putting this together
Earned a sub. Thanks for schooling us in such a clear, no nonsense non patronizing way.
once again, another great electrical video from you guys. Keep creating more esp diagnosing common issues like on ivan's channel.
Thanks for the comments
Yep, absolutely true. A number of years ago, I was given a old car by a friend that just wanted to get rid of it. One headlight was full brightness, but one was very dim, and I couldn’t tell the diff between high and low beams. He told me that no one had been able to locate the problem.
I traced the problem to a corroded ground wire on the dim headlight. The current was finding its ground path through the other filament, then to the other headlight through the wiring. I added a separate ground wire to the circuit on the dim side… worked perfectly!
Wow. Such a good explanation of that measurement. More importantly “clear”.
Happily subscribed. 👍🏼🇨🇦
This is a great lesson for my airmen. I'll be showing them this and reviewing the lesson principals with them next week. Thanks!
Heads up:
In a circuit, let’s say a light bulb or electric motor, if you unplug the ground side and test it, you WILL get voltage on that ground side. Voltage still flows through the filament or motor windings. Keep this in mind when diagnosing.
I'm almost certain that is not true. If you still get voltage, something is on somewhere. Modern cars almost always have a some sort of computer, that'll stay on for 15-20min after the car is off(usually pulls .300-.800 volts) . If it's a higher end vehicle, they usually always have a computer on, which is why the battery dies after a couple weeks of it not being started.
Blackhawk 7r I believe you are right about measuring current on the negative side of filament , current flows all the way to the end of a circuit even if the end of that circute is the neg. side of a filament . the reason the lightbulb does not light is because the current is static and not flowing , their is no continuous flow of current. That given that the switch is on , if the switch is off then current stops at the switch .
Absolute gold....I have and old Jeep and JCB backhoe I am always messing around and this just popped up in my video feed. Exactly what I needed, thank-you for the great content. Subscribed.
Great video, now I know why I'm always getting electrocuted, I know next to nothing about electricity and I'm 71, worked on many a vehicles but wiring not my cup of tea just do not understand it no matter how simple you put it. Liked and subscribed, hopefully you can teach an old dog some new tricks.
Good to see your spirit for learning is still strong sir
Thank you! You make a dark and mysterious subject so much clearer by simplification.
High resistance in your ground circuit. Poor connection or possible battery cable issue. Ideally the circuit needs to be under load. Turn headlights on would be a good load. Without having the circuit under load you will get an inaccurate reading