Sorry so long between posts folks. Kind of a really crazy week at the shop that set me way behind! Trying to play catch up this week and get things back to "normal." What ever that is 🥴
Normal is 10 viewers calling 9 Rusted bolts 8 dead brand new parts 7 Jerry's Jerried 6 hacked up wires 5 trouble codes 4 bald tires 3 faulty brakes 2 dead wipers and a dead pcm for you.
That's right and both O2 sensors were replaced. Eric should get a court order to have the O2 sensors exhumed so that he can do a post mortem on them. LOL 🤣 Good catch AJ
Hey Mr O I’m sure I’m not the only person who would rather have a video where you point the camera at the screen than no video because you don’t have time to mess around... I certainly appreciate the fact that you do take time to do videos from a working shop and a busy one at that.. keep up the great work
all things considered, you probably have the best youtube channel on the internet .....you could have made it big in hollywood but you would have had a miserable life there .... a man of many natural talents ....not very common any more
There is no need to aplogise Eric. Us viewers benefit way more than we could express. You have to earn an income to pay all your bills, wages and support your family. Somewhere in there you are a husband and parent and your dogs need you too! I am thankful you take the time to put out the videos. You and Mrs O are champions!!
5V on that line suggests it's conducting through a body diode in one of the semiconductors. The welding likely blew out the 0V/GND switching element to the 02 sensor. It's a good idea to always use two ground clamps when welding - one either side of the joint!
In my opinion the input is differential and the "signal ground" is not a ground otherwise you can't get 4,62V out of if. In case you're right the body diode short and the track on the pcb burn and open. As I did write in my opinion the input is differential (also suggest by the draw in the wiring diagram) and the signal reference is not at 0V. This beacause of the high impedance of the output of an O2 sensor output is more sensitive to external EM noise. A good test would be measure the other O2 sensor signal reference if they are a 0V or not. The original problem could be anyway in the ECU.
@@andreavico6198 I think it's likely the ground element was damaged during the welding, so now the only path is through that internal ESD diode. The wiring diagram showed that the ground to the sensor was not a true ground, it was switched in some way - presumably to protect itself if it was shorted to some other rail.
@@DAZ_SR it's there to allow engine torque load movement, now it will likely break the exhaust manifold flange gaskets up and start leaking or break the gasket downstream.
Your troubleshooting and deductive skills are something to behold. I'm sure if they handed you a schematic for the ECM you could figure out which IC was bad and what junction was shorted. Watching you work is like watching a good who done it movie.
Fuck man I’m working on one right now, replaced faulty t body, then drove for 1 hour all went well 2 days later traction control goes off but no misfires. Damn thing never had a check engine on and still doesn’t and it’s fucking up -.-
It was meant as a goof on "What we have here is a failure to communicate." Cool Hand Luke movie. Meaning that there shouldn't have been any current communicating along the circuit. I think the joke just lost something in the translation.
Dude, I kinda got interested in your channel about a month ago when I was looking for instructions on a Honda Civic EP2 (01-05) rear wheel bearing replacement. Back then I thought you were mostly into the heavy and rusty stuff with your puller and Big Nasty... But now I am very surprised about your diagnostic abilities. Thumbs up and best wishes from Germany! Keep it up, dude!
unplug all the sensors and connectors nearby, as there are large induction fields around the welding area, which induce currents where things shouldn't be. even with the fabricobbled exhaust work, I'm still not positive the welding is what got that ECM though! maybe old O2 wires melted together and someone played the keep fuse swapping game. I forget if the heater on those is +12V ignition source and ground side PWM switching or not.
Great day on a day of Saturday with an German beer to watch Eric work, love your show watching it from Mississauga Ontario Canada. I'm only 71 years and an old farmer in Alberta told me once he you young wipersnaper don't throw anything away doing my break fluid flash. He said break fluid he is using to remove rusty spark plugs and bolts as well. I said I know better and try it broke off the spark plug. Happy to say it was a lesson to me.
When welding on any computer control vehicle I would always ground clamp the welder within inches of the weld. If the item being welded was not capable of being clamped by the ground clamp, I would clamp a small piece of flat stock in the ground clamp and spot weld it to the part first, very near to the weld area, then proceed to weld up the part. Keep the weld electron path small and you will not cause the wild pixies to wander thru the computer ...... Mr. O, your synopsis on the cause of the blown computer is spot on !
You don’t have to comment and say your busy. It’s written all over the place with your demeanor. I know this feeling all to well. Glad to see your human like the rest of us LOL 😆
What I would do for the heck of it to take the PCM apart look on the inside and see if any noticeable component is blown which is sending a 5 volt charge to ground. Excellent diagnostic skills that's why I love watching South Main Auto!
I love this channel. This guy is always very detailed in his explanations and what he shows during the repair. That's good for those of us studying automotive technology
Disconnect the PCM when welding. Ground to the object you want to weld. These suggestions are born of wisdom, which you cant learn out of books. Experience is the teacher. Bang yore hayyiddd!
Hey Eric, a Bosch tech warned me to watch out for so much as a pinhole leak in the exhaust. I asked "Do you mean a vacuum leak in the engine?" No. A tiny hole in the exhaust admitting Oxygen. He had one that was so small that it didn't show when he smoke tested it. He ended up putting 5 psi of compressed air into the tailpipe and brushing the exhaust with a solution of soapy water. Bubbles! He welded the pinhole and all of a sudden the O2 sensor worked fine. They are exceedingly sensitive to oxygen.
Bought a shirt, hopefully you get a few bucks out of that. I love your content; working on a car is tedious enough but with a camera and teaching people while you go truly is a feat unto itself.
OMG dude I finally found your channel again!! I first started watching when you only had like 1500. Last time I saw you only had like 60K congrats on half a million!! So happy to of found you again man you're seriously one HELL of a mechanic man. Taught me soo much, how to test sensors, scope things, the harder stuff nobody really teaches. Keep up the good work man!!
Great tip about welding shorting out circuits. Just had a similar PCM situation on a Dodge (P0571 brake pedal performance, C**** brake pedal 1/2 stuck) that was shorted to voltage from the PCM on a circuit that should have been zero. Replaced the PCM from an online seller that pre-flashes it to your VIN. Contact me direct for a referral, don't want to advertise someone who's not a sponsor on E's channel!
I love all of your videos!! I love your customer service style, and i love your honest fixes! Good job on this one! I wish you were local, because i'd turn you loose on my 06 Sonata.... Yay!
In the diagram the PCM showed switched ground(s), I wonder if the code set criteria disables the O2 sensor depending on conditions after a failure. You should clear all of the codes and see if the ground returns when the PCM commands it. Great video as always Eric!
I think the switched ground shown is for the heater ckt. The other two ckts measure the voltage of the O2 sensor itself, tho I could be totally wrong on that.
I had replaced a pcm on a 2009 1500 Silverado 5.3l last winter, because you could not longer connect to it and dash lights and gauges would flicker on and off like it had crap ground in the run position, It would not longer allow the starter to engage ether. He gave the vin to flagship I believe a business somewhere in New York. All I did is plug the new PCM in hook the battery up everything worked like nothing was ever wrong before.
I used to be a mechanic on a banger (stock car) team, engines needed battery and coil and away they went. Now you need a licence to fly that computer stuff. I'm glad I'm out of it now. great content keep it up
One more "test" would be to probe the other downstream O2 ground to see if it has any voltage on it for comparison sake. But, with the fan issue and such I agree it needs a new box.
Had the same thought, maybe for circuit integrity test had something similar on a MAF signal ground the other day, reading 12.5v but not enough grunt to light a test lamp.
I recently found your channel and I love it, It reinforces my joy in not having a shop anymore. Now I only work on classic cars, points, plugs and condensers. no computers except in my head. And not for anyone else other than myself. Good job of educating people in what not to try to fix on their vehicles.
Thanks Mr O. I am having the same problem on my Silverado. 200k miles. Rep;laced cats, o2's, mass air, pcv, coils, plugs wires, fuel injectors and still o2 bank 2 errors. Even swapped upstreams. I have just replaced the BCM due to many errors and now I think the ECM on my Chevy Thunder is bad.
Without even watching the video first,,,,,,, Im going to go out on a limb and guess O2 sensor. Now. Off to the video. I own a 1970 Trans Am and have had it and MANY hot rods for years. No one else touches my vehicals even tho I am a retired union electrician and fiber optic engineer. My point is i love watching your videos Mr. O but ever since I seen Mrs. O honk the horn while you were messing with the coils the other day ..... That's when I figured out who the real star of the show is ;)
When I worked for a shop building ambulances, it was a strict rule in the place that if you had to weld on the vehicle, make sure to unhook the batteries. The electrical department guys would scream when someone forgot and they had to repair all the damaged circuits that would cause. As Eric said in the video, even with the battery unhooked, the welding current can find it's path to ground via sensitive electronics and fry things.
Completely agree on your theory. Sounds like the welder found a path through the O2 sensor ground. I had a similar thing happen to my own car after I had a shop weld up my exhaust. Fortunately just blew the O2 sensor in this case, not the PCM.
You are an electrical genius! Well but your really good at finding cause without the old test parts that a lot of people will try before they give up, like the owner of this car.
I agree the welding could have easily fried a transistor or two in the ECM. In computers even a small static charge when working on them is enough to fry a component or two. Another reviewer posted that two grounds when welding in close proximity to the weld is great strategy for controlling the current to a defined area. Kudos for posting that bit of info.
Those PCMS have a high failure rate especially after engine hot soak. Often use a heat gun to diagnose. Difficult to impossible to complete monitors with aftermarket sensors.
Forgive me gentlemen for my ignorance but what is an "Engine Hot Soak"? I'm literally an oil change and parts changer for the fleet of ancient vehicles at my house. So is it where the engine gets warmed up and is shut off and sits for a little while?
@@charlesabbott9605 after driving the vehicle especially for longer periods at higher speeds and then turning the vehicle off. The temperature under the hood significantly increases because there is no longer air movement and the exhaust manifolds are much hotter than the engine itself.
@@shango066 Thank you sir for your fast reply. I googled it but it didn't make sense until I read your reply. Light bulb moment Thank you very much. Wait so is that why on my son's old Volvo the fans would run under the hood after the car was shut off?
@@charlesabbott9605 that would be correct. I used to own a Volvo and it wasn't' uncommon for the fans to run for a good 10 min or so after a long drive.
Wish you were in Vegas. But grew up with a dad who is a mechanic and he worked the same way. Great info to have when and if I have issues with my 2020 F-150 XLT 4 x 4. That way I can ask good questions. All my Fords have been 10-15 years with no major issue so I hope I’m good with mine now. Thanks Mr. O
I wonder if Eric O should change his name to Eric E, being the auto genius that he is. You always know the geniuses since they make these things appear deceptively & ridiculously easy.
I was thinking,that with all that electronic garbage ,on Cars these days .Welding without unplugging sensors may be a Big No no. Not like the cars I worked on,in the late 60's for sure. Thank you Eric.
Seems to me all his problems started with a welder and the hack job on the exhaust. Maybe he should have unplugged the pcm before welding...lol. Probably smoked the pcm with high amps the welder puts out. He`s a Jerry that now needs a pcm. Sometimes you can really screw the pooch jerry rigging it to try to fix it. Why not just replace the flex pipe with oem part. I learned that lesson years ago, smoked a pcm when I forgot to unplug it and the battery welding up a cracked pipe on a dodge I inherited. Had all kinds of problems..lol. Replace pcm with a salvaged unit and sold it. Only Dodge I`ve owned. Got an old Chevy truck with a few issues, fixed them, still runs great and it`s my daily. Now I won`t have anything obd2..too complicated, no expensive scanner needed. Thanks for taking us along for the ride Eric. My next project is installing a digital dash in my 91 Chevy C1500. I hope there is no smoke when I do it, that dash was not cheap, but old one is shot..only speedometer and gas works. Oil pressure, temp, odometer, volts are dead(moonie gauges suck) lol. If I lived closer I would just drop it off and have you install it. Stay safe, God Bless.
I had a similar one at work once. ECM case had been shorted to battery positive. Lots of strange things going on with the car, like 7V on a 5V Referece - in the end, the internal ground pin had desoldered itself from the PCB, a little blob of solder was on the lower lid. Resoldered it and the box was OK again...
You disconnect the battery to keep it from getting blown up. You also disconnect the ECU to keep it from getting smoked. The very nature of welding is overvoltage and overamp. Inverse of high voltage (electrode close to work) is high amps (electrode farther from work) which is I = P / V
If the weld job toasted the ECM, there would have been enough energy to burn through other insulators. All it would take is a sensor appearing to go bad with a crossed ground. If a sensor wire in the same sheath as the o2 sensor, it could have been compromised as part of the weld ground path. Not a mechanic, enjoy your videos! Thanks!
Great Video, I have followed many of yours as I appreciate your approach to finding problems. I have an Acadia, same car as in this video, just like yours I have the Bank 2 after cat O2 sensor reading very lean, I can loosen a vacuum line and watch all 4 O2 sensors respond very well but within 20 seconds of closing my vac leak the B2 sensor 2 goes lean, 75-150 mv constant read. I removed the entire Cat and Exhaust manifold, cleaned, inspected and re installed with new gaskets and the problem is exactly the same. I sprayed brake clean all over the cat and its connections and can't find a leak? The exhaust smells clean as if the cats are working well. The only odd condition is the idle is slightly rough and the B2 LTFT is running 14% + while the B1 LTFT is running 10% +. Swapped the O2 sensors with no change. FYI: Other mechanics have been in this car before me, every test I have done I see someone has been there before me. I am starting to wonder if I have a slightly plugged injector on Bank 2 but I did not detect it in a power balance test. Thanks again for your Videos, I have been a wrench a long time and still learn a lot from your work.
Couple more notes, Vacuum is a steady 19". Intake manifold was removed and new gaskets installed, Intake valves cleaned to remove carbon build up but all had no affect on the lean B2 S2 readings.
Well, the first attempts to find a leak did not work so I hooked up my shop vac to the exhaust, had to get tricky because of 4 exhaust tips but got that done and pressurized the system with air, searched for leaks using a spray bottle and soap/water mix. Low and Behold the leak is around the 2 mounting bolts just before the after cat O2 sensor. Since it already has a brand new gasket and is tight but still leaking I need to find a solution to seal it up but at least a solution to the leak has been found. I really sprayed that area hard with brake clean but never picked up the rich signal on my scanner, must be a slow or tight leak. Thanks again for your training videos.
I fixed the leaks in my Bank 1 at the Cat, made no change in my Lean Reading S2 B2 O2 sensor. Still reads lean. On cold start it works perfectly, both B1 and B2 after cat sensors warm up and start reading around 700 very steady, after about 5 minutes run time the B2 S2 goes lean and stays lean running around 70-140 mv constant. LTFT's both start running lean with 10+ all the time, B1 usually under 13 but bank 2 goes as high as +19. Trips the P2099 code. ODD, disconnect the B2 S2 O2 sensor and the LTFT's will start coming down. I am thinking the Cat is fine but somehow air is being introduced. Engine has great power, no sign of a blockage in exhaust, only run issue is slightly rough weak idle, feels like a vacuum leak to me but won't show itself spraying brake clean.
good call on welding likely killing the ecu earth circuit . Only going be bigger issue with all the modern poor quality electronics . I recently replaced earth lead on my mig with longer one so can keep as close as possible to torch .
Those negative references are created by the circuit... like a regulator, but a regulator for ground, a 'virtual ground'. Chances are it was also the ground for the cooling fan sensor, or its ground was nearby when the insult happened. Shade tree pecker-tracks all over this one.
A guy that worked for me left the grinder plugged in and sitting on the welding table while welding. Smoke rolled from the grinder. Lesson here. Path of least resistance. Look between weld and ground. Keep all circuits clear.
I have this saying and most of the time it comes true - Maintenance is the chief cause of maintenance - lol. I worked on aircraft for 31 years and it seems that after we did an inspection on the aircraft - taking the aircraft apart, it caused problems that were not there before the inspection. As in the maintenance on the exhaust that might have damaged the PCM.
This reminds me of when I was in the USAF in the Strategic Air Command (SAC). General Curtis LeMay was the Commander, this really dates me, and he had initiated a policy of "if it ain't broke, don't fix it". He had done this because there were so many problems caused by people messing with things that were still working ok.
Same symptom o2 sensor on bank two O2 sensors exhausted on replaced the PCM code and o2 sensors working. Fans would go on high just like yours and now they don’t even com on except when needed
@13:30 Please explain why dielectric grease is bad for electronic connections. I though it was used on dissimilar metals such as the aluminum entrance panel wires to the brass bus in house electrical panels?
I have a traverse with this exact problem. But when i unplug the maf sensor, the voltage on the o2 sensor drops back to normal. Not sure what it means , but thats how far i got with it. Im no mechanic, and dont got fancy tools like you do 😂
Sorry so long between posts folks. Kind of a really crazy week at the shop that set me way behind! Trying to play catch up this week and get things back to "normal." What ever that is 🥴
Hi
No problems Mr. O...crazy seems to be the new normal these days ;)
Normal is
10 viewers calling
9 Rusted bolts
8 dead brand new parts
7 Jerry's Jerried
6 hacked up wires
5 trouble codes
4 bald tires
3 faulty brakes
2 dead wipers
and a dead pcm for you.
Whatever Mrs. O says it is!
interesting video, strange that it is putting out a live supply, must have cooked a switching transistor or something like that.
I guess Jerry also has a welder...
🤣🤣
That weld was too good for Jerry...
@@HouseCallAutoRepair Nope. Notice how it "screws" around and overlaps and is "oops, gotta try that again"?. 🤣🤣
@Jerry P 🤣🤣
looks like a flux core from "The Freight"
Guarantee you that that nice, convenient 02 sensor bung right next to the welding area made one heck of a good place to attach a ground clamp.
That's right and both O2 sensors were replaced. Eric should get a court order to have the O2 sensors exhumed so that he can do a post mortem on them. LOL 🤣 Good catch AJ
Hey Mr O I’m sure I’m not the only person who would rather have a video where you point the camera at the screen than no video because you don’t have time to mess around...
I certainly appreciate the fact that you do take time to do videos from a working shop and a busy one at that..
keep up the great work
Agreed, honestly the video looks fine 2nd hand, almost prefer it - for the "authenticity"
Yeah, it looks fine to me. I can see everything, not sure why anyone would complain.
100% agree !! Thanks for taking the time to show us. You did however have some beard hairs out of place, gotta knock you on that. sorry.
all things considered, you probably have the best youtube channel on the internet .....you could have made it big in hollywood but you would have had a miserable life there .... a man of many natural talents ....not very common any more
There is no need to aplogise Eric. Us viewers benefit way more than we could express. You have to earn an income to pay all your bills, wages and support your family. Somewhere in there you are a husband and parent and your dogs need you too! I am thankful you take the time to put out the videos. You and Mrs O are champions!!
5V on that line suggests it's conducting through a body diode in one of the semiconductors. The welding likely blew out the 0V/GND switching element to the 02 sensor. It's a good idea to always use two ground clamps when welding - one either side of the joint!
In my opinion the input is differential and the "signal ground" is not a ground otherwise you can't get 4,62V out of if. In case you're right the body diode short and the track on the pcb burn and open. As I did write in my opinion the input is differential (also suggest by the draw in the wiring diagram) and the signal reference is not at 0V. This beacause of the high impedance of the output of an O2 sensor output is more sensitive to external EM noise. A good test would be measure the other O2 sensor signal reference if they are a 0V or not. The original problem could be anyway in the ECU.
@@andreavico6198 I think it's likely the ground element was damaged during the welding, so now the only path is through that internal ESD diode. The wiring diagram showed that the ground to the sensor was not a true ground, it was switched in some way - presumably to protect itself if it was shorted to some other rail.
@@sdgelectronics another test to proof your theory is measure if the signal reference is short or isolate from the metallic case of the O2 sensor.
@@sdgelectronics or the a ground trace is blown and there's other things tied to it, which are now raised above ground and back feeding!
18:56 - "I don't know all the electrical mumbo jumbo that happens in there" best definition of a "black box"
Yea he does. He's just pulling your leg
Your common sense approach has stimulated my thinking and problem solving on several occasions. Thank you from an old mechanic.
That guy not only had a parts cannon, he had some leftover pipe and a welder. “Flex pipe? Who needs that”
Maybe he needed the flex pipe for the Parts Cannon. I mean, you have to conduct the plasma burst to the projectors somehow....
The owner of that Traverse over the first bump.
@@DAZ_SR it's there to allow engine torque load movement, now it will likely break the exhaust manifold flange gaskets up and start leaking or break the gasket downstream.
Yeah! You dam'n right. Spare parts are totally overrated. Better look on the goodie pile first😁
Your troubleshooting and deductive skills are something to behold. I'm sure if they handed you a schematic for the ECM you could figure out which IC was bad and what junction was shorted. Watching you work is like watching a good who done it movie.
Different brand, doesn't make the noise. Love it!
Don't worry. We are just lucky viewers that you run a repair shop & still take the time to make videos whenever you can, THANKS
The analyzing of this type of problem is so important.
It has become common place to just bring out the parts cannon at most repair facilities..
11 years of college, and I didn't even keep up with you. Damned inspiring.
The ol traverse. The Chevy cavalier of today's Suv's
The terrain and equinox are the cavaliers of suvs.
Don't forget the Corsica !😅
@@ColdStartAuto Only with near perfect maintenance, BTW any decent car should make to at least 150K without major failures.
Fuck man I’m working on one right now, replaced faulty t body, then drove for 1 hour all went well 2 days later traction control goes off but no misfires. Damn thing never had a check engine on and still doesn’t and it’s fucking up -.-
@@AndrewKidd14145 GM electronics/wiring is on par with Chinese Christmas lights.
"What we have here, is a failure to not communicate."
I think Martin used the word "got"
It was meant as a goof on "What we have here is a failure to communicate."
Cool Hand Luke movie.
Meaning that there shouldn't have been any current communicating along the circuit.
I think the joke just lost something in the translation.
What we have here, is failure to not communicate."
Good analysis!
Always disconnect your battery negative before you do any welding!
The classic long travel welding earth.
Rusty exhausts make bad grounds for welding, wiring looms make really good ones.
Dude, I kinda got interested in your channel about a month ago when I was looking for instructions on a Honda Civic EP2 (01-05) rear wheel bearing replacement.
Back then I thought you were mostly into the heavy and rusty stuff with your puller and Big Nasty...
But now I am very surprised about your diagnostic abilities.
Thumbs up and best wishes from Germany! Keep it up, dude!
Eric O has been teaching automotive system troubleshooting for years. The heavy rusty stuff is his side job.
Thanks for the upload Eric. No worries on the delay. We know these videos aren’t easy to produce when you’re busy.
Thanks for the heads up! I always disconnect the bat but, will unplug the PCM and bat from this point forward when welding.
unplug all the sensors and connectors nearby, as there are large induction fields around the welding area, which induce currents where things shouldn't be.
even with the fabricobbled exhaust work, I'm still not positive the welding is what got that ECM though! maybe old O2 wires melted together and someone played the keep fuse swapping game. I forget if the heater on those is +12V ignition source and ground side PWM switching or not.
I thought Eric forgot about us, we missed you man.
I love your videos since I'm semi retired from a car accident. Your an excellent instructor.
Learned from a old school mechanic, he always brazed exhaust on the newer cars. A major pain, but never had electric or computer fails
A SMA upload and Line of Duty season finale, this Sunday is awesome!!
Greetings from a British guy in Germany!
Yep been saying that it makes no difference if welding with or with out the battery been hooked up or not keep the ground next to where ones welding
After 24 hours of live ranching, this is a perfect Sunday morning video
Convoluted path to find the problem. Congratulations on your determination to find the problem.
Great day on a day of Saturday with an German beer to watch Eric work, love your show watching it from Mississauga Ontario Canada.
I'm only 71 years and an old farmer in Alberta told me once he you young wipersnaper don't throw anything away doing my break fluid flash.
He said break fluid he is using to remove rusty spark plugs and bolts as well.
I said I know better and try it broke off the spark plug.
Happy to say it was a lesson to me.
Thanks for the thought process on tracking this kind of problem down
Thanks for the video Eric. We all appreciate what you do!
When welding on any computer control vehicle I would always ground clamp the welder within inches of the weld. If the item being welded was not capable of being clamped by the ground clamp, I would clamp a small piece of flat stock in the ground clamp and spot weld it to the part first, very near to the weld area, then proceed to weld up the part. Keep the weld electron path small and you will not cause the wild pixies to wander thru the computer ...... Mr. O, your synopsis on the cause of the blown computer is spot on !
You don’t have to comment and say your busy. It’s written all over the place with your demeanor. I know this feeling all to well. Glad to see your human like the rest of us LOL 😆
What I would do for the heck of it to take the PCM apart look on the inside and see if any noticeable component is blown which is sending a 5 volt charge to ground. Excellent diagnostic skills that's why I love watching South Main Auto!
Very insightful diagnosis at the end that the ground got shorted out inside the PCM when they were welding on the O2 sensor. Dr. O to the rescue!
I love this channel. This guy is always very detailed in his explanations and what he shows during the repair. That's good for those of us studying automotive technology
I never realized that the brake clean sound was brand specific. Good to know!
Disconnect the PCM when welding. Ground to the object you want to weld. These suggestions are born of wisdom, which you cant learn out of books. Experience is the teacher. Bang yore hayyiddd!
Josh was working hard on the audio today 😂 great troubleshooting video mate - you're awesome 🏆
Hey Eric, a Bosch tech warned me to watch out for so much as a pinhole leak in the exhaust. I asked "Do you mean a vacuum leak in the engine?" No. A tiny hole in the exhaust admitting Oxygen. He had one that was so small that it didn't show when he smoke tested it. He ended up putting 5 psi of compressed air into the tailpipe and brushing the exhaust with a solution of soapy water. Bubbles! He welded the pinhole and all of a sudden the O2 sensor worked fine. They are exceedingly sensitive to oxygen.
Bought a shirt, hopefully you get a few bucks out of that. I love your content; working on a car is tedious enough but with a camera and teaching people while you go truly is a feat unto itself.
Nice one. I always hate having to call an ECM unless I can totally prove its bad.
I’ve got it easy, I’m a collision tech so when I call an ECM it’s kind of obvious because it’s usually been smashed.
OMG dude I finally found your channel again!! I first started watching when you only had like 1500. Last time I saw you only had like 60K congrats on half a million!! So happy to of found you again man you're seriously one HELL of a mechanic man. Taught me soo much, how to test sensors, scope things, the harder stuff nobody really teaches. Keep up the good work man!!
Great tip about welding shorting out circuits. Just had a similar PCM situation on a Dodge (P0571 brake pedal performance, C**** brake pedal 1/2 stuck) that was shorted to voltage from the PCM on a circuit that should have been zero. Replaced the PCM from an online seller that pre-flashes it to your VIN. Contact me direct for a referral, don't want to advertise someone who's not a sponsor on E's channel!
A different brand of brake clean doesn't make the sound...lol, who knew?!
Nah, he's mistaken. I got a guy who tells me it's the same stuff, just a different label. Don't let him fool you!
I love all of your videos!! I love your customer service style, and i love your honest fixes! Good job on this one! I wish you were local, because i'd turn you loose on my 06 Sonata.... Yay!
Good job. You have to program the new pcm to the vehicle. Some people may not know that.
In the diagram the PCM showed switched ground(s), I wonder if the code set criteria disables the O2 sensor depending on conditions after a failure. You should clear all of the codes and see if the ground returns when the PCM commands it. Great video as always Eric!
I think the switched ground shown is for the heater ckt. The other two ckts measure the voltage of the O2 sensor itself, tho I could be totally wrong on that.
I had replaced a pcm on a 2009 1500 Silverado 5.3l last winter, because you could not longer connect to it and dash lights and gauges would flicker on and off like it had crap ground in the run position, It would not longer allow the starter to engage ether. He gave the vin to flagship I believe a business somewhere in New York. All I did is plug the new PCM in hook the battery up everything worked like nothing was ever wrong before.
I used to be a mechanic on a banger (stock car) team, engines needed battery and coil and away they went. Now you need a licence to fly that computer stuff. I'm glad I'm out of it now. great content keep it up
Thanks for the content Mr. O, how's Mrs. O like her Kia Sedona van so far? Stay safe and keep on fixing things you are a good teacher.
One more "test" would be to probe the other downstream O2 ground to see if it has any voltage on it for comparison sake. But, with the fan issue and such I agree it needs a new box.
Had the same thought, maybe for circuit integrity test had something similar on a MAF signal ground the other day, reading 12.5v but not enough grunt to light a test lamp.
I recently found your channel and I love it, It reinforces my joy in not having a shop anymore. Now I only work on classic cars, points, plugs and condensers. no computers except in my head. And not for anyone else other than myself. Good job of educating people in what not to try to fix on their vehicles.
Thanks Mr O. I am having the same problem on my Silverado. 200k miles. Rep;laced cats, o2's, mass air, pcv, coils, plugs wires, fuel injectors and still o2 bank 2 errors. Even swapped upstreams. I have just replaced the BCM due to many errors and now I think the ECM on my Chevy Thunder is bad.
Send Ivan in to take apart that ECU, he'll solder in a paperclip for a "no-parts" fix!
it's likely potted under shmoo with nothing visible or clear gooey shmoo that's hard to remove. last ECM I tried around that year was.
My SMA tee shirt should be here this week! I shall wear it proudly. Probably the only one in Western Canada?
My 2nd should be here Tuesday. Don't know how many in SW Pennsylvania
No, I'm sure there's more than 1 tee shirt in Western Canada, it just isn't a SMA one. :)
Nice one and I agree it’s likely they welded it with the O2 connector attached and trashed the ECM.
Without even watching the video first,,,,,,,
Im going to go out on a limb and guess O2 sensor.
Now. Off to the video.
I own a 1970 Trans Am and have had it and MANY hot rods for years. No one else touches my vehicals even tho I am a retired union electrician and fiber optic engineer. My point is i love watching your videos Mr. O but ever since I seen Mrs. O honk the horn while you were messing with the coils the other day
.....
That's when I figured out who the real star of the show is ;)
Great video, experience is the answer, hard work does not hurt either, Thanks
🤔 Wonder if when the welding was done the battery was left hooked up and it partially fried the pcm Eric O @SouthMainAutoRepairLLC
When I worked for a shop building ambulances, it was a strict rule in the place that if you had to weld on the vehicle, make sure to unhook the batteries. The electrical department guys would scream when someone forgot and they had to repair all the damaged circuits that would cause. As Eric said in the video, even with the battery unhooked, the welding current can find it's path to ground via sensitive electronics and fry things.
@@richb.4374 which is why I made that comment
Battery can also absorb the stray currents, could even have limited the damage. Proper method is very important when welding on a car.
@@casparberends2719 yes that is true but if the battery couldn't absorb all of the current it would have gone to other components
Completely agree on your theory. Sounds like the welder found a path through the O2 sensor ground. I had a similar thing happen to my own car after I had a shop weld up my exhaust. Fortunately just blew the O2 sensor in this case, not the PCM.
You are an electrical genius! Well but your really good at finding cause without the old test parts that a lot of people will try before they give up, like the owner of this car.
I agree the welding could have easily fried a transistor or two in the ECM. In computers even a small static charge when working on them is enough to fry a component or two. Another reviewer posted that two grounds when welding in close proximity to the weld is great strategy for controlling the current to a defined area. Kudos for posting that bit of info.
Those PCMS have a high failure rate especially after engine hot soak. Often use a heat gun to diagnose. Difficult to impossible to complete monitors with aftermarket sensors.
Forgive me gentlemen for my ignorance but what is an "Engine Hot Soak"? I'm literally an oil change and parts changer for the fleet of ancient vehicles at my house. So is it where the engine gets warmed up and is shut off and sits for a little while?
@@charlesabbott9605 after driving the vehicle especially for longer periods at higher speeds and then turning the vehicle off. The temperature under the hood significantly increases because there is no longer air movement and the exhaust manifolds are much hotter than the engine itself.
@@shango066 Thank you sir for your fast reply. I googled it but it didn't make sense until I read your reply. Light bulb moment Thank you very much. Wait so is that why on my son's old Volvo the fans would run under the hood after the car was shut off?
The issue here is that the B+ on the horizontal output tube is too low.......
@@charlesabbott9605 that would be correct. I used to own a Volvo and it wasn't' uncommon for the fans to run for a good 10 min or so after a long drive.
Well explained about how the welding ruined the ecm
Your logic in trouble shooting is excellent! Thank you for the information! It's a fine video, folks!
Wish you were in Vegas. But grew up with a dad who is a mechanic and he worked the same way. Great info to have when and if I have issues with my 2020 F-150 XLT 4 x 4. That way I can ask good questions. All my Fords have been 10-15 years with no major issue so I hope I’m good with mine now. Thanks Mr. O
Life is good. Eric is great. Mechanics are crazy. (Break clean sound effects)
legend has it Eric diagnoses a dull knife before sharpening it
I wonder if Eric O should change his name to Eric E, being the auto genius that he is. You always know the geniuses since they make these things appear deceptively & ridiculously easy.
Wow, impressive diagnosis on the box and knowing how it must have failed. Good job :)
Replacement PCM do an autopsy on the failed one would be a great video Mr. O !
I was thinking,that with all that electronic garbage ,on Cars these days .Welding without unplugging sensors may be a Big No no. Not like the cars I worked on,in the late 60's for sure. Thank you Eric.
Seems to me all his problems started with a welder and the hack job on the exhaust. Maybe he should have unplugged the pcm before welding...lol. Probably smoked the pcm with high amps the welder puts out. He`s a Jerry that now needs a pcm. Sometimes you can really screw the pooch jerry rigging it to try to fix it. Why not just replace the flex pipe with oem part. I learned that lesson years ago, smoked a pcm when I forgot to unplug it and the battery welding up a cracked pipe on a dodge I inherited. Had all kinds of problems..lol. Replace pcm with a salvaged unit and sold it. Only Dodge I`ve owned. Got an old Chevy truck with a few issues, fixed them, still runs great and it`s my daily. Now I won`t have anything obd2..too complicated, no expensive scanner needed. Thanks for taking us along for the ride Eric. My next project is installing a digital dash in my 91 Chevy C1500. I hope there is no smoke when I do it, that dash was not cheap, but old one is shot..only speedometer and gas works. Oil pressure, temp, odometer, volts are dead(moonie gauges suck) lol. If
I lived closer I would just drop it off and have you install it.
Stay safe, God Bless.
So you recommend if doing any welding work on the car too always disconnect the negative battery cable?? Or actually disconnect the PCM?
Never saw a heater circuit do that! Ok, on to the next one! Hopefully another PCM will fix the problem.
I had a similar one at work once. ECM case had been shorted to battery positive. Lots of strange things going on with the car, like 7V on a 5V Referece - in the end, the internal ground pin had desoldered itself from the PCB, a little blob of solder was on the lower lid. Resoldered it and the box was OK again...
You disconnect the battery to keep it from getting blown up. You also disconnect the ECU to keep it from getting smoked. The very nature of welding is overvoltage and overamp. Inverse of high voltage (electrode close to work) is high amps (electrode farther from work) which is I = P / V
Great video! I usually fix this type of problem with an average to large size hammer.....
Nuke it from orbit!
I love the chevrolet intro. No emphasis intended.
If the weld job toasted the ECM, there would have been enough energy to burn through other insulators. All it would take is a sensor appearing to go bad with a crossed ground. If a sensor wire in the same sheath as the o2 sensor, it could have been compromised as part of the weld ground path. Not a mechanic, enjoy your videos! Thanks!
Great Video, I have followed many of yours as I appreciate your approach to finding problems. I have an Acadia, same car as in this video, just like yours I have the Bank 2 after cat O2 sensor reading very lean, I can loosen a vacuum line and watch all 4 O2 sensors respond very well but within 20 seconds of closing my vac leak the B2 sensor 2 goes lean, 75-150 mv constant read. I removed the entire Cat and Exhaust manifold, cleaned, inspected and re installed with new gaskets and the problem is exactly the same. I sprayed brake clean all over the cat and its connections and can't find a leak? The exhaust smells clean as if the cats are working well. The only odd condition is the idle is slightly rough and the B2 LTFT is running 14% + while the B1 LTFT is running 10% +. Swapped the O2 sensors with no change.
FYI: Other mechanics have been in this car before me, every test I have done I see someone has been there before me. I am starting to wonder if I have a slightly plugged injector on Bank 2 but I did not detect it in a power balance test. Thanks again for your Videos, I have been a wrench a long time and still learn a lot from your work.
Couple more notes, Vacuum is a steady 19". Intake manifold was removed and new gaskets installed, Intake valves cleaned to remove carbon build up but all had no affect on the lean B2 S2 readings.
ZERO mis Fires in this engine recorded. MAF Sensor swapped as a test with no change.
Well, the first attempts to find a leak did not work so I hooked up my shop vac to the exhaust, had to get tricky because of 4 exhaust tips but got that done and pressurized the system with air, searched for leaks using a spray bottle and soap/water mix. Low and Behold the leak is around the 2 mounting bolts just before the after cat O2 sensor. Since it already has a brand new gasket and is tight but still leaking I need to find a solution to seal it up but at least a solution to the leak has been found. I really sprayed that area hard with brake clean but never picked up the rich signal on my scanner, must be a slow or tight leak. Thanks again for your training videos.
I fixed the leaks in my Bank 1 at the Cat, made no change in my Lean Reading S2 B2 O2 sensor. Still reads lean. On cold start it works perfectly, both B1 and B2 after cat sensors warm up and start reading around 700 very steady, after about 5 minutes run time the B2 S2 goes lean and stays lean running around 70-140 mv constant. LTFT's both start running lean with 10+ all the time, B1 usually under 13 but bank 2 goes as high as +19. Trips the P2099 code. ODD, disconnect the B2 S2 O2 sensor and the LTFT's will start coming down. I am thinking the Cat is fine but somehow air is being introduced. Engine has great power, no sign of a blockage in exhaust, only run issue is slightly rough weak idle, feels like a vacuum leak to me but won't show itself spraying brake clean.
Sorry, leaks fixed in B1 and B2 with no change.
Excellent, as always! Love watching these bug shooting videos. Always learn something. Tnx!
Damn I thought you had gained Jedi accreditation when the fan kicked in after saying " Ill give it a little throttle"
Me too, thought he had Gumby arms or something
good call on welding likely killing the ecu earth circuit .
Only going be bigger issue with all the modern poor quality electronics .
I recently replaced earth lead on my mig with longer one so can keep as close as possible to torch .
And here I thought you were perfect and didn't make any mistakes. Haha all the best from Canada
At 6:14-6:25ish, super interesting... the pcm significantly increases the o2 heater command at the same time the o2 voltage goes high.
Those negative references are created by the circuit... like a regulator, but a regulator for ground, a 'virtual ground'. Chances are it was also the ground for the cooling fan sensor, or its ground was nearby when the insult happened. Shade tree pecker-tracks all over this one.
A guy that worked for me left the grinder plugged in and sitting on the welding table while welding. Smoke rolled from the grinder. Lesson here. Path of least resistance. Look between weld and ground. Keep all circuits clear.
Always love how you tackle the issue... Thanks
Nice little challenge. I've heard that you should unplug the PCM when welding on a car, but who knows. Thanks Dr. O!
Also remove the PCM when driving thru high water if you are not James Bond -
Unplug the booster hose to jack air into the system to get your O2 signal running quicker, I use that method on cat efficiency faults
I have this saying and most of the time it comes true - Maintenance is the chief cause of maintenance - lol. I worked on aircraft for 31 years and it seems that after we did an inspection on the aircraft - taking the aircraft apart, it caused problems that were not there before the inspection. As in the maintenance on the exhaust that might have damaged the PCM.
This reminds me of when I was in the USAF in the Strategic Air Command (SAC). General Curtis LeMay was the Commander, this really dates me, and he had initiated a policy of "if it ain't broke, don't fix it". He had done this because there were so many problems caused by people messing with things that were still working ok.
When are you going to start college or institute, you would be an amazing teacher Eric. The Institute of "Here's you problem lady" has a ring to it.
You guys hiring I'd love for you to be my boss! Watch a lot of your videos very very knowledgeable explain stuff perfect!
Got a similar issue on a Ford van, guess that's one more thing to check before I start opening up the loom...
That is 100% what happened. Unplug stuff before welding. I watched a guy have the chains hooked to a job, started welding and the crane motor smoked.
Same symptom o2 sensor on bank two O2 sensors exhausted on replaced the PCM code and o2 sensors working. Fans would go on high just like yours and now they don’t even com on except when needed
@13:30 Please explain why dielectric grease is bad for electronic connections.
I though it was used on dissimilar metals such as the aluminum entrance panel wires to the brass bus in house electrical panels?
Dielectric grease at such low current levels acts as an insulator and can screw up the readings. It's better to use an contact oil product.
You shouldn't use it on low voltage connections. Ford makes a special grease specifically for low voltage use.
I have a traverse with this exact problem. But when i unplug the maf sensor, the voltage on the o2 sensor drops back to normal. Not sure what it means , but thats how far i got with it. Im no mechanic, and dont got fancy tools like you do 😂