How to Catch an Intermittent Bad Cam or Crank Sensor
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- เผยแพร่เมื่อ 12 พ.ย. 2022
- A trick to helping "catch" an intermittent Cam or Crank sensor failure and collecting enough data that you can make a diagnosis instantly onm iof the sensor is bad or not.
Visit my website at www.schrodingersboxQM.com for basic diagnostics training and case studies and to download or free book.
See more case studies and follow me on Autel!! accufix.autel.com/ - ยานยนต์และพาหนะ
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If the sensor gets "stuck" for whatever reason pulling your reference signal voltage to the ground, you might think that you have a wiring issue while, in fact, you have an internal failure of the sensor (internal short to ground). So, if that happens, you need to disconnect the sensor and see if the reference voltage goes back to 5V with the sensor disconnected.
Also, the supply voltage for the sensor could be 12V (battery voltage or maybe even stabilized 12V), it is not always 5V.
The ABS sensors on modern cars are Hall effect sensors and they only have two wires (off the top of my head, signal output serves as a ground too). And various position sensors also use the Hall effect element in their circuitry and have three wires, but they output analog signals.
Just found your channel, and you sir provide great technical information with enough common sense to back it. I love it and I'll be following your channel from now on.
Welcome aboard!!!
Like hitting a hole in one or bullseye ! It doesn’t get any better ! Super clever! 🏹🎯 Much appreciated !
Learning so much from these videos, really love the scientific approach, thank you! Nowhere near the 2% yet more like 50. However, inspired to do better my audi was starting badly and stalling when hot. Scanner showed intermittent crank sensor, forget code. Looked up the spec for resistance, unplugged it and was in spec. Damm! But tried harder. Started the engine let it run till it stalled. Checked resistance, open circuit! Replaced sensor and running fine now!
Nice work!!! Yes the problem is while it was working you will see the normal resistance. you have to catch it fail.
@@SchrodingersBox thank you! While it turned out to be what the code said, I did not want to fire up the parts cannon. Was so happy to get under the car knowing that was the problem rather than hoping.
My 2007 Dodge Charger is having this problem and was wondering how I was going to "properly" diagnose this. Tomorrow will be a good day to try to tackle this and I'm saving this video and going to be referencing this video as I do. Thank you. I have a crank no start since June of 2022( last summer.) All started after changing the ECT sensor got a horrible rattling sound instantly on first start and everyone after. Thought I had a pulley bearing going out or something and every since I took the serpentine belt off it will not start. Cranks forever and ever and at my wits end with it stressing out. Even had to basically go out and get another vehicle so I had transportation for work and everything else lol.
Updates..?
Great video man. Keep it up don’t get discouraged
Another great video man....wish more people wouldn't assume the cat is just dead without checking inside the box....your awesome.
I think checking the box is the point.
Thanks, this was exactly what I was looking for. Logical and visual.
Awesome seeing you upload more frequently lately :D
More to come!
Great video man. I was just passing through for some information but you’ve won me over to subscribe and check out more of the channel. Thank you sir.
Glad to hear!!!!
Good job SQ box. No signal but if you did, then wiring integrity to PCM. Had one guy splice connectors but he mixed up the wires; good thing these wires from PCM do not carry or apply load. You can short them all you want but you only get a high or low circuit code which is great for wiring integrity testing with a test light.
Yes I have a video with a shorted reference wire and the PCM did not blow thanks to the internal resistor from the 5V reference circuit.
Now I have seen 12V reference signals before on some sensors but even then, the way it works with it being pulled to ground it still shouldn’t blow the PCM if it shorts out- that’s what the sensor does anyway. I have done a bypass of those before but I was still nervous about it and used my test lamp but I don’t doubt a paper clip would have still been just fine.
I think you are digging that Picoscope! Showing good use of it.
my favorite tool!!
Brilliant logic.
Damn you're good... lol this is why I watch your channel
as usual great job
Well done
One variable might be if the sensor ground pin fitment was loose/dicky. By backprobing the sensor, your scope connection to the sensor ground may stay good and you will still see 5V on the sensor signal wire, but a dicky sensor ground connection to the sensor will not allow the sensor to pull down the 5V reference, and hence it won't produce a square wave signal, potentially it will just pass the 5V reference straight through and out of the signal wire👍🇦🇺
agreed!
I have a 2007 Buick Lucerne 3.8 V6 and I have the problem of sometimes it cranks but has the auto start problem where it keeps on trying to crank. It also stalls occasionally at low speed. Sometimes it will go for weeks without a problem before it does it again. I've been at a loss to figure this one out. I haven't taken it to the dealership because it happens so seldom that I'm sure they won't be able to find it. This is the first video that I've seen that referenced the problem of it keeps trying to crank once started.
Have you located the problem?
Had my changed before it was car would shut off now it doesn't but runs like crap showing 336code also had cam and crank done can't do relearn because it won't go to 4000rpm what should i tell them to look for when I take it to the shop
Thanks indeed
your the man
Good stuff
4:36 is that really how you picture the viewers of this channel 😂 ive noticed that on a lot of ur videos 😅 otherwise, another very informative and well explained video.
Not the viewers of this channel… critics of this channel.
Nice explanation of the crank sensor GODSPEED
Great job My fried
Thank you kindly!
Thanks so much
Any time!
I have a question about probing. If I have a 3 wire sensor for example… 12v power, ground, and 5v reference/signal; and I want to test the 5v signal, do I place the positive lead on the 5v signal wire and the black test lead on the ground wire or do I put it on chassis ground?
I’m really trying to get an overall understanding (in case I don’t have wiring diagrams) of how not to fry the computer.
It depends on the design but on virtually all of them the signal will be a positive voltage so you will have one lead of DVOM on EITHER the sensor ground or chassis ground and the other on the signal wire.
The ground doesn’t matter as far as the reading however if you don’t see a signal, you will want to try putting meter to chassis ground because maybe the sensor ground is bad. Remember you are probably looking at a sensor issue if you are doing this, right?
Also keep in mind if you don’t see signal it might be because there is no reference.
Usually what I do is I put one lead to the reference and the other to the sensor ground. If I see the reference voltage then I know both the reference is good and sensor ground is good right there. If I don’t see the reference voltage I will move the lead from sensor ground to chassis ground and if I now see voltage, you know the sensor ground is bad. If I still don’t see reference, I know there is missing reference signal.
Wonder if my 07 dodge ram has this issue when I turn to crank the 1st time wont start unless car is hot but when cold I need to go for a 2nd crank. My other issue is truck stalls when I'm coming to a stop at a sign or light.
could be. when it happens just check any easy to access coil for ground.
Great video and explanation. My 2005 Wrangler TJ continues to display a DTI P0344 intermitent cam sensor. I think it may be do to a wiring issue since changing out the cam sensor doesn't improve matter. I wish I knew how to find a person like yourself in the Seattle area as I know nothing about trouble shooting this situation. Do you have any advise or maybe you might want to take a short vacation to my part of the country?!?!
Well shoot man, wish I could help but no plans to be in Seattle anytime soon.
All I can suggest is my cam and crank sensor video on www.schrodingersboxqm.com which literally walks step by step through this diagnosis.
Hello, thank you for such an informative video. Can anyone tell me if reference voltage or ground is lost, will the voltage shown be '0.0?' Thanks everyone, for trying to build my knowledge.
it will if you measure against that lost ground. check against a chassis ground to confirm voltage is present or the ground is missing.
Is there a way to diagnose a cps not pulling all the way down to ground with a dvom?
Yes- you would basically do a voltage drop measurement between the sensor ground at the sensor and the low reference pin at the PCM. it should have no voltage drop. if it does then there is an interference in the ground.
I got a no crank no start On a two thousand three chevy trail blazer four point 2 Six cylinder. I changed the old spark plugs removed all 6 Old ones. I put the new ones in and it started up but it was misfiring. So I changed the ignition coils around and it still was misfiring so I did not have my scan tool so I ASSUMED IT WAS the spark plugs I just purchased and put the old ones back in. When I put the old ones in, now it doesn't want to start. So I again put the new ones back in and it still crank no start. I got codes po300 .. what the heck do you think happened? Could it be my camshaft sensor or solenoid
what data do you have? Since you don’t have a scantool just stick with the extreme basics - what is you signal voltage at the coils showing and is ground side switching conformed?
Not all hall effect sensors are the same... you need to consider pull-down type designs. The pcm sends 5v, through an internal resistor, to the hall effect sensor signal wire. The sensor itself will pull this signal to ground when triggered. So your exact test, where you measure voltage between the signal wire and ground, would result in a bad sensor even if it was unplugged (sensor has clearly lost power supply and ground). I feel it's important to check all wires.
Also, not all hall effects are the same... look at the crank position sensor diagram for an 02 maxima. It uses 12v and ground for the sensor's power supply. This is a strong indicator to expect a pull-down design, as the signal wire is highly unlikely to have a 0-12v square wave -- the 5v is sourced from the pcm on the signal wire.
good points. You are absolutely right. still even more begs my point which is to think in terms of associating wires with their functions. Doing so would adapt the testing accordingly.
but I should have clarified the generalization better.
Hi sir a good smoke or picoscope machine will do us good back here in Africa 🌍.thanks
Merry Christmas
Hey thank you!! You as well!!
LOVE IT@!!!...
Good video. Can cam sensors fail intermittently without throwing fault codes?
Yes for sure. The code depends how long the signal is missing and also how consistent it is missing.
Thumbs Up, please. It helps Scrot. 😀...errrr, Bernie
Matt, agree with your explanation of scoping using signal and sensor ground, but you DO need to scope reference as well, due to most Hall sensor outputs being "open collector output" aka "pull down design".
The ECM provides the 5V via a resistance on the signal line, it does not come from the sensor.
The sensor pulls that signal voltage to ground or just releases it, rather than drive it up to 5V.
So, if you lose your sensor 5V supply (reference), the signal will still go to 5V
@Simon Parkinson This only applies if the ECM is utilising a 5V 'bias' voltage on the signal wire. If that is the case, we would only see the bias voltage on the signal wire at initial key on with the sensor unplugged. With the key on, engine not running, and sensor plugged in, we will likely also see close to 5V on on the signal wire of a pull down sensor that doesn't use a bias voltage, unless a tooth of the crank or cam reluctor happens to be in line with the sensor at the time, then we might see a low voltage. Matt showed the zero volt scope reading before starting the engine but not sure if he already had the key on at that point.🤷
Hey vriend ,ik hb een isuzu 4hl1 ,wel crank en nokass sensor vernieuwd,maar tog geen resultaat,,wat doen ?? meer te doen ??? Van uit Suriname..
Du hast mich gefragt und du hast mich gizagdt!
That borla hat doe I need one
My "pointer" on my tachometer is unreliable it jumps back and forth on its own when idling....
What could be the reason
hundreds of reasons what data do you have? what’s your CKPS voltage showing?
What if you aren't getting any code? Periodically cranks but won't start. 2008 corvette ls3.
Then apply FASTTEC method when the issue happens.
I almost never see a code on a cranking no start.
Oh, man - you suck! You didn't even tell us what color wires we're supposed to be looking for! 🤣
On a more serious note, I'm so glad that your work with Autel is working out so well; their website is a fantastic resource. And congratulations on teaming up with Dr. Ayman Kamar and his new publication - I'm sure the book will provide the perfect complement to the Schrodinger's Box library of videos.
ANDY!!!!! Dude !!! Vicki and I were just wondering where the hell you have been!! She was afraid something happened to you lol!!! Great to see you back.
@@SchrodingersBox LOL I've been out in my lawn chair recently - drinking lemonade.
Funny how I always seem to pop up when you discuss me. 😂
Send my best to Vicki - at least somebody is looking out for me!
Interesting is, RPM didn't reflect sensors bad output while it should spark timing, shouldn't it? Also could be good to mention potential problems only when engine block (and sensor) are hot, is it correct?
Good observation on the RPM. I do believe it’s because the Crank sensor provides the RPM signal as opposed to cam sensor(s).
@@SchrodingersBox Engine should stall as a precaution since crankshaft position (piston top dead center) is now unknown so spark timing is only estimated and bad spark timing can cause problems. I would expect more sanity from ECU..
Yea but remember there are TWO cam sensors on this vehicle. Maybe the other is being used as reference when one dies?
@@SchrodingersBox Oh my goodness, I thought all this time you were testing crankshaft sensor 😵💫
Hahahaa yeah you had me confused there my friend lol!!!! All makes sense now, right?
even I can understand this.... thanks
I changed my camshaft sensor work fine for about 2 or 3 days and then went right back to like it was faulty again engine light came on and pushed the gas and it's like it's not getting power idles fine and everything but turns over too many times to start but it does start what's causing this like I said it's a brand new camshaft sensor we're fine for 2-3 days and then went right back again
The camshaft sensor work fine for 2-3 days and then went right back tomorrow's number for
@@RandallHorn-sf6nxI read sometimes certain brand cam sensors are shit compared to others.Not saying that’s your problem but Thats just something to keep in mind.
Did you put dielectric grease in that plug???????
No. Why would I do that?
Excellent video, Thank you for posting, ,,,Btw do you have a Garage 'moggy' (cat?) was curious with that cat meeeow noise at start of video ? 🤔,,, 🙂👍
no, I hate cats lol.
@@SchrodingersBox 🙂 Lol,,, 😁
@@SchrodingersBox i have a friend who adopted an abandoned little kitten,and didn't want to take it home, because his wife is asthmatic,so he decided to make a home for it at his workshop,a small wooden enclosure in the corner of his office,with carpet and food and milk bowls, he was stuck for a name for the new arrival, until the 'Snap-on' man pulled up, he quickly decided to call it 'Spanner' that little kitten has become the 'Star' that everyone wants to see,and responds well to the 'Name' allocated to it ,,🤔,,😻,,,thought i'd share this true story, although the little Moggy is struggling to get to grips with all your 'tutorials' esp when i play them at 1.75X above the normal speed 🙄😁🙂 take care and Bless 😇
Hahaha that’s a great story lol!!
@@SchrodingersBox 🙂😻👍
Just changed my altima 2014 crank sensor due to no spark. It did not help. Took it to the dealer and they said after market sensors don't work in Nissan cars. I wish I knew that.
I find that pretty suspicious. The factory sensor worked??
Aint true. I have nissan frontier. Truck completed stalled dead on freeway which scared me to death with no CEL warning. Towed to my honest mechanic, code p0335 ( i think) replaced after market. Back on the road again.
Is it possible to be a pull up instead of a pull down ?
it’s possible but I have never seen one that is pull up.
@@SchrodingersBox then the 5v KOEO u see is not verifying u have a good 5v ref only ground and signal circuit integrity... u migth have been loosing ur 5v ref preventing the hall pulling to ground..? cheerz, great compact vid man!
Hey Matt, you should update to PicoScope 7. Waaay better.
oh I totally agree!!! The problem is when I got my new laptop, there is some type of incompatibility with Pico7 (known issue with the type of Intell processor my laptop has) so I grudgingly had to downgrade to Pico 6 again.
I believe they probably have a patch by now though so thanks for reminding me- I’ll check for it!! I absolutely want to get back to 7!
what causes crank sensor to keep failing . replaced 3 in the last 6 months .
What is the nature of the failure. What part of the sensor is failing? Is it the power, ground or signal output?
@@SchrodingersBox I don't know , I put a new one in , fault code Crank sensor and goes good for 2 to 3 months then starts hesitating again and stalls . The first time i took it to a dealer due to no fault codes . They couldn't find what was wrong with the car . So i changed the fuel pump , no fix then the Crank sensor and ran perfect for a few months . Then stalled with engine light , Crank sensor fault . Changed it again and now this is the third one that has failed . must be something to cause it to keep failing .
So what data do you have?
Just check your Cam position sensor connector and ECU terminal(s) and if those are ok then just replace the sensor!.
I’m having the intermittent need to crank over 20 times to start problem. A strong deiseling smell once it finally starts. How do you know if it’s camshaft or crankshaft sensors? The problem so far ONLY HAPPENS ONCE THE CAR has been driven…is hot…then shut off for 20-30 minutes. Hasn’t happened on a cold start…so far.
What is your crankshaft sensor data showing?
@@SchrodingersBox Taking it to my Toyota mechanic Friday
Thank you for the video.
I am a subscriber to your site. I would like to contact you for some issues.
Thank you.
You can email me at erwinschrodingersbox@gmail.com
Does anybody know where this guy is located??
Denver Colorado.
Well darn...!! I'm in Florida. I've had a mystery issue with my car and several mechanics haven't been able to figure it out. I wish you were closer 😔. Very good videos to watch even if a person knows nothing about cars. Thanks!
Here's a challenge for you I have a 1996 Ford explorer and it has rough idil and done times it shut off while driving and I don't have scoop or any tools your use in your videos besides test light and the crank sensor is dirty it's the original crank sensor from 1996 I looked for vac leak and and I don't have one a shop replaced the valve cover gasket ever since I had this problem and I just don't want to replace the part if it's not the sensor and no engine light on
It’s not a challenge- there just isn’t any data here. Do you have any data at all to get even a beginning starting point?
@@SchrodingersBox when I had the valve cover and intake gaskets replaced it would not stay running because the place that replaced them made a air leak and then fixed it and it was fine for a day or so then it started to have a rough ideal then I did research on the internet and found out it could be the PCM crank sensor fual filter or spark plugs so I replaced the fuel filter and I know it's not the pump because that went out on me and I replaced that already so I went to replace the fuel filter to to see if it would fix the problem but it didn't I have a dmm I'll see if I have 5 voltage at the sensor and a test light that it i dont have. Your scan tool to do the data you can get
Just some basic reference and signal voltages would be a start. Right now there is nothing.
LOOK NEED HELP NOWWWW..... i have a 2006 honda accord ex 2.4L 4 door sedan Ahh my car shut off while driven point is the Starter is whining wngine not turning over bendix want turn flywheel no sound from engine at all Starter is Whining only ANDD my 3rd New starter does the same thing so its not the starter what is it / cam amd crank sensor i know but still what is it still ??
Wire harness is good fuel pump good switch battery didn't work so what els spark plug ok so what els
broken timing belt?
Impossible I already checked that's not it
Starter shimmed incorrectly? How did you verify timing belt isn’t broken?
I have not even shimmed it because it's on correctly and I checked that as well but I find out it could be the crankshaft pulley or shaft itself if so I will just add new parts
Hi there! It’s been a minute.
hahaha trying to make up for lost time
Yes sir! lol
On Subarus a dying battery like it around 11 volts and 10 volts will cause multiple usually Bank One cam sensor off the eyesight will shut off rip will shut off throw engine code and it's really just due to bad battery it could also be haven't changed the oil in a while in a CB in a valve engine system, changing your oil more often does wonders
Any car with a dying battery can get any number of codes. I have seen cars with bad alternators that threw 20 check engine codes for everything from timing to transmission.
10:30 on a Sunday night, I don't want to think so much. And watch football,
Hahaha I can appreciate that! watch it while you are at work instead!!
I wish the paid channel would get more uploaded videos
One is coming this weekend!
@@SchrodingersBox you and your videos are yhe best
Dude.
2.8 min
"You didn't tell the wire color"..
No good to say any wire colors anyways cause brands use different colors than others so if ppl think the color matters it will more than likely be a different color on their rig
EXACTLY!!!!!!!!!! I wish more people understood that. can you imagine the hate mail I would get if I said to ground the green wire but on someone’s car the green wire is a power feed from the PCM and grounding the wire shorted the PCM?
You get it bro!!
@@SchrodingersBox iv been working on a ton of different brand rigs for the passed 20+ years iv seen alot of different color grounds and powers on different brand rigs
Yeah and the “reddish colors are powers and greenish colors are grounds” is a horrible rule. On my GM vehicle, the power for the crank sensor is perfectly green lol.
@@SchrodingersBox yup i can 100% agree with that cause it can be red on one green on another or blue no one knows untell its checked to figure it out on that rig its self
Lol they want readers digest version. We want war and peace version
Hahaha yeah but I understand their strategy- they basically want a service that competes with the Snap On thing-not sure what it’s called but basically on a code it shows what % of people changed a part and reported success. I think it’s called intellifix or something. I hate that system because it isn’t diagnosing - it’s guessing still. Hell I don’t even believe the data is true in there anyway hahaha. how many people replaced a part and reported it fixed but then didn’t report the comeback?
@@SchrodingersBox it’s the parts cannon list . But for most DIY folks it’s better then guessing it educated guessing 👊🏻
MEOOOOOW. 🐈