I know this type of video takes a lot longer to make, but these test your showing is what it takes to find the problem, and what people don't realize goes into being a professional, and not guessing. Greatly appreciate your channel
It is very hard to find a good diagnostic anywhere, especially on TH-cam. You are a professional. You not only fix problems but you also try to show and teach us how to do it, speaking slowly and clearly so that we can understand. I really appreciate your time and the effort that you put into it. Keep up the good work! I wish you all the best!
Well I have to disagree with you Jake. If you think you’re an idiot for forgetting one thing I think all of us are doomed. Your knowledge is so impressive to me. I know it’s a figure of speech and we’re our worst critics. Keep up keeping up. 👍
Love that you show the different techniques and why one may be better than the other. Videos that show testing techniques and why one may be better than another, may help some from going down a rabbit hole. Great job!
I've learned a valueable lesson on a Lexus recently. Always disconnect the battery before plugging or unplugging any modules. The lexus has a psc module that is bolted to a bracket. The module grounds through that bracket. I unbolted the bracket doing some other work. I had turned the ignition on checking some voltages in the fuse box and bumped the pscm which allowed the bracket to contact the chassis that it is normally mounted to. After fixing the original issue the vehicle ended up having multiple comm codes along with 4 of the 40 modules off the network. Ended up finding out the pscm was dragging that leg of the network down. The module was damaged which cost a lot of coconuts. I'm just thankful none of the other modules were damaged. Been doing this for 28 years without damaging modules, but that day changed my processes.
Hey Jake the 3.6 has known issues with the oil pressure sensor pigtail deteriorating and the 5V /Grd touch pulling the circuit down causing multiple codes including some of the codes you have. This pigtail/ sensor is under the intake manifold on the oil cooler. Try to borescope the pigtail under the rear of the intake manifold.
Thanks for sharing Jake . Wow I never heard someone say that as a troubleshooting strategy . I’ll be thinking of that probably till you post part 2 . Thanks again 👍
Great case study Jake. 😎👍 BTW... I scan that QR code with my phone to send to my customers the Pre and/or Post scans via text or whatever method they may want. I find it to be really handy. Looking forward to part 2.. Cheers
Excellent, very well explained diagnostic procedure, Jake! When using an ohmmeter it's important to remember that the meter applies a small DC voltage to the leads, to measure the resistance (voltage level depends on the meter range used) and, if there is a spurious voltage on the circuit, it will bias the meter reading! An easy check is to reverse the leads - if reading changes, there is a spurious voltage on the circuit. Wondering if something else could drop the PCM voltage, other than the PCM itself and the only possibility I could think of, is some sort of corrosion inside the plug, pulling the 5V pin to a nearby grounded pin, but only when all pins are connected to the PCM.
i swear you must be watching me at work 🤣🤣🤣🤣 i almost got caught out earlier this week with that ohm check on an ecm circuit i was testing but something in my gut was telling me “that ain’t right “ and oh yes voltage on the line 🤪🤪🤪 i tell you i have hunted that test light and over here it’s as rare as unicorn 💩
Excellent video Jake! If I don't have a reference voltage supply by PCM and like in this case is not being cause by the sensor or another sensor circuit and I am calling the PCM as the root cause of the problem I have to make sure all voltages supply to the PCM are reaching the PCM as well as the grounds. There are some components that needs those grounds! Powers and grounds check before advising a new ECU. Also, I would have tested the other sensors reference voltages the same way you did with this circuit to have a better picture for analysis.
The reistance gets thrown off because the multimeter does not directly measure resistance. In resistance measurement mode, the meter actually applies a known voltage to the circuit and measures the current through the circuit, then uses Ohm's law to determine resistance and the result is displayed as ohms on the meter. R=V/I. Add stray voltage or current from another source and it messes up the measurement because the meter has no way of knowing that the stray voltage or current is coming from some place other than the meter.
Hi Jake, The ultrdiag should be able to screen record. Actually, I really love this scan tool for this feature. Which the graphing could be better, though. Thanks for the video and the explanation with using resistance as a test.
Many sensors ground internally in the PCM (Sensor Ground) so if you unplug the PCM your also removing the sensor ground, if a sensor's 5v is shorted internally to sensor ground unplugging the PCM would make the short go away when just checking between 5v supply and chassis ground. I would want to check for shorts between the 5v supply wires and the sensor ground wires as well before condemning the PCM.
Need to test Voltage and ground on the pcm, one more question if any of the other sensors share a 5v reference, maybe one of them is short circuited and of course the 60 ohm pcm resistance at the end 😊😊😮
I noticed a long time ago that I would get false ohm readings using my Fluke 77 and couldn't figure out why (scratch head). I did discover that my Simpson 260 an old school analog meter (with a real meter LOL) would read correctly! I suppose the Simpson's meter would 'load' the circuit somewhat and give a more acurate reading. I really don't know.
Jake I just watched the video again and if you replace the PCM now is it a new or used PCM ? Are there any other sensors using 5v you could disconnect to bring the 5v ref. Back to life ? I’m just running this thru my old brain . Everyone usually says check the PCM for a good ground . To be honest let’s hope that the new PCM just fixes the problem . I’m trying but I’m just a retired old Aircraft Mechanic trying to learn these electronic time machines. Lol. 😡Artie
Computer Powers and Grounds. Is the PCM Internal APP Ground Ref above or at PCM Ground? What other PCM inputs/outputs can cause the 5 Volt References to be at zero volts. Plug in APP connector at the back of the engine and measure APP 1&2 5 Volt Powers and Ground References shorted to chassis Ground by testing at the disconnected PCM connector pins. Verify those connections and/or the APP assembly or wiring through the bulkhead are not shorted. What about the APP assembly itself? It's a start.
@autodiagyt My friend, the 5V line is shared with the crankshaft sensor and the oil pressure sensor. There may be an internal short circuit in one of the sensors, or a short circuit to ground with the crankshaft sensor or ground with the oil pressure sensor.
I'm wondering, when you had your testlight connected and it was lit showing a short to ground, couldn't you just unplug the module connectors and if the light went out it would indicate the short is going through the module and or the module itself is shorted. So now if the short is going through the module could it be connected to another external sensor that may be shorted pulling the 5 volt ref circuit down, the old voltage follows the path of least resistance rule. So if you find that sensor and unplug it, your short will go away and your 5 volt ref will return? Is it possible that the circuit could be shorted to ground by a sensor that shares the 5 volt ref? This is my thought. Can't wait for part 2.
Hi, I have one question and if somehow maybe you can help :) I' am from Europe(Serbia) I have Opel Astra K 2017, a few mouths a go I have problem with my power steering weel , so I bought a used from some creased car but is very good condition, we puted on my car and it's working, but tracking assisten line not, so I plan to by VXDiag Nano for GM and try to reprogram this part, Is this possible?? Or Can you help me with this??? Thanks you for your advice and answer
The issue with an LED Test like is that it's almost no current and the circuit of the LED is very voltage dependent, it's either enough voltage to turn it on or not. It's hard to get a LED to just be dim. I think most LED Test lights only load the circuit to about 15milliamp so my test light pulls about 4 times that and is still computer safe. I'm not even sure a LED Test light will turn on with a 5v circuit but my test light does, which you will see tomorrow in part 2.
I know this type of video takes a lot longer to make, but these test your showing is what it takes to find the problem, and what people don't realize goes into being a professional, and not guessing. Greatly appreciate your channel
It is very hard to find a good diagnostic anywhere, especially on TH-cam. You are a professional. You not only fix problems but you also try to show and teach us how to do it, speaking slowly and clearly so that we can understand. I really appreciate your time and the effort that you put into it. Keep up the good work! I wish you all the best!
Love how you teach on your videos. I know im not the only one who learns from this. Thank you.
Got the popcorn out...Is it going to be a bad PCM? PLACE YOUR BETS NOW! ;)
Well I have to disagree with you Jake. If you think you’re an idiot for forgetting one thing I think all of us are doomed.
Your knowledge is so impressive to me. I know it’s a figure of speech and we’re our worst critics. Keep up keeping up. 👍
Love that you show the different techniques and why one may be better than the other. Videos that show testing techniques and why one may be better than another, may help some from going down a rabbit hole. Great job!
I've learned a valueable lesson on a Lexus recently. Always disconnect the battery before plugging or unplugging any modules. The lexus has a psc module that is bolted to a bracket. The module grounds through that bracket. I unbolted the bracket doing some other work. I had turned the ignition on checking some voltages in the fuse box and bumped the pscm which allowed the bracket to contact the chassis that it is normally mounted to. After fixing the original issue the vehicle ended up having multiple comm codes along with 4 of the 40 modules off the network. Ended up finding out the pscm was dragging that leg of the network down. The module was damaged which cost a lot of coconuts. I'm just thankful none of the other modules were damaged. Been doing this for 28 years without damaging modules, but that day changed my processes.
Good lesson and case study Jake! Thanks for posting. Can't wait for P2!
Again great video, can't wait for the conclusion!
Can't wait for the conclusion!
Hey Jake the 3.6 has known issues with the oil pressure sensor pigtail deteriorating and the 5V /Grd touch pulling the circuit down causing multiple codes including some of the codes you have. This pigtail/ sensor is under the intake manifold on the oil cooler. Try to borescope the pigtail under the rear of the intake manifold.
But didn't ohm testing the 4 5v circuits to ground show no continuity to ground, or maybe he should have lied tested the 4 5v circuits
It could be. 5v (camshaft 1 and 2, crankshaft, oil pressure sensor, tps, app, map sensor ) may be one of them shorted pull 5v to ground
Thanks for sharing Jake . Wow I never heard someone say that as a troubleshooting strategy . I’ll be thinking of that probably till you post part 2 . Thanks again 👍
Great case study Jake. 😎👍
BTW... I scan that QR code with my phone to send to my customers the Pre and/or Post scans via text or whatever method they may want. I find it to be really handy.
Looking forward to part 2..
Cheers
Excellent, very well explained diagnostic procedure, Jake! When using an ohmmeter it's important to remember that the meter applies a small DC voltage to the leads, to measure the resistance (voltage level depends on the meter range used) and, if there is a spurious voltage on the circuit, it will bias the meter reading! An easy check is to reverse the leads - if reading changes, there is a spurious voltage on the circuit. Wondering if something else could drop the PCM voltage, other than the PCM itself and the only possibility I could think of, is some sort of corrosion inside the plug, pulling the 5V pin to a nearby grounded pin, but only when all pins are connected to the PCM.
great video Jake and good explanation of what was going on with the ohm meter. as usual I always learn something from your videos.
i swear you must be watching me at work 🤣🤣🤣🤣 i almost got caught out earlier this week with that ohm check on an ecm circuit i was testing but something in my gut was telling me “that ain’t right “ and oh yes voltage on the line 🤪🤪🤪 i tell you i have hunted that test light and over here it’s as rare as unicorn 💩
These are the test that trip techs up! It’s happened to me before.
Shoot me an email and I’ll see if I can get you one. GM changing the special tools website I’m not sure if it’s available right now or not.
Excellent video Jake! If I don't have a reference voltage supply by PCM and like in this case is not being cause by the sensor or another sensor circuit and I am calling the PCM as the root cause of the problem I have to make sure all voltages supply to the PCM are reaching the PCM as well as the grounds. There are some components that needs those grounds! Powers and grounds check before advising a new ECU. Also, I would have tested the other sensors reference voltages the same way you did with this circuit to have a better picture for analysis.
great video thanks for such a simple and to the point explation
The reistance gets thrown off because the multimeter does not directly measure resistance. In resistance measurement mode, the meter actually applies a known voltage to the circuit and measures the current through the circuit, then uses Ohm's law to determine resistance and the result is displayed as ohms on the meter. R=V/I. Add stray voltage or current from another source and it messes up the measurement because the meter has no way of knowing that the stray voltage or current is coming from some place other than the meter.
Hi Jake, The ultrdiag should be able to screen record. Actually, I really love this scan tool for this feature. Which the graphing could be better, though. Thanks for the video and the explanation with using resistance as a test.
Many sensors ground internally in the PCM (Sensor Ground) so if you unplug the PCM your also removing the sensor ground, if a sensor's 5v is shorted internally to sensor ground unplugging the PCM would make the short go away when just checking between 5v supply and chassis ground.
I would want to check for shorts between the 5v supply wires and the sensor ground wires as well before condemning the PCM.
Thanks, professor.
Excellent video great stuff 👊🏻
Maybe load test the 4) 5v circuits from the disconnected computer side with the low current testers hooked to positive
Need to test Voltage and ground on the pcm, one more question if any of the other sensors share a 5v reference, maybe one of them is short circuited and of course the 60 ohm pcm resistance at the end 😊😊😮
I noticed a long time ago that I would get false ohm readings using my Fluke 77 and couldn't figure out why (scratch head). I did discover that my Simpson 260 an old school analog meter (with a real meter LOL) would read correctly! I suppose the Simpson's meter would 'load' the circuit somewhat and give a more acurate reading. I really don't know.
Jake I just watched the video again and if you replace the PCM now is it a new or used PCM ? Are there any other sensors using 5v you could disconnect to bring the 5v ref. Back to life ? I’m just running this thru my old brain . Everyone usually says check the PCM for a good ground . To be honest let’s hope that the new PCM just fixes the problem . I’m trying but I’m just a retired old Aircraft Mechanic trying to learn these electronic time machines. Lol. 😡Artie
If u have a 5v ref 2 circuit.. u could de pin 5v #1 circuit and jump to 5v #2 circuit..
Grasias
Computer Powers and Grounds. Is the PCM Internal APP Ground Ref above or at PCM Ground? What other PCM inputs/outputs can cause the 5 Volt References to be at zero volts.
Plug in APP connector at the back of the engine and measure APP 1&2 5 Volt Powers and Ground References shorted to chassis Ground by testing at the disconnected PCM connector pins.
Verify those connections and/or the APP assembly or wiring through the bulkhead are not shorted.
What about the APP assembly itself?
It's a start.
Shouldn’t BOTH ends of the circuit be disconnected (TPS and ECM) to measure a short to ground on that circuit ??..should see OL if no short to ground.
I did that test later in the video.
@autodiagyt
My friend, the 5V line is shared with the crankshaft sensor and the oil pressure sensor. There may be an internal short circuit in one of the sensors, or a short circuit to ground with the crankshaft sensor or ground with the oil pressure sensor.
I'm wondering, when you had your testlight connected and it was lit showing a short to ground, couldn't you just unplug the module connectors and if the light went out it would indicate the short is going through the module and or the module itself is shorted.
So now if the short is going through the module could it be connected to another external sensor that may be shorted pulling the 5 volt ref circuit down, the old voltage follows the path of least resistance rule. So if you find that sensor and unplug it, your short will go away and your 5 volt ref will return? Is it possible that the circuit could be shorted to ground by a sensor that shares the 5 volt ref? This is my thought.
Can't wait for part 2.
Very good logical thinking!
Check powers and grounds at module before replacing module
You arent an idiot we all stumble on absentmindedness
Check the throttle itself if it's going to ground.
Hi, I have one question and if somehow maybe you can help :) I' am from Europe(Serbia) I have Opel Astra K 2017, a few mouths a go I have problem with my power steering weel , so I bought a used from some creased car but is very good condition, we puted on my car and it's working, but tracking assisten line not, so I plan to by VXDiag Nano for GM and try to reprogram this part, Is this possible?? Or Can you help me with this??? Thanks you for your advice and answer
So did you disconnect the battery??
Nope. The difference was the PCM still awake trying to supply power to the 5v circuit.
👍💙
❤❤❤❤❤❤❤
12 min in, didn't notice any audio issue.
Can we you Led test light is that computer safe
The issue with an LED Test like is that it's almost no current and the circuit of the LED is very voltage dependent, it's either enough voltage to turn it on or not. It's hard to get a LED to just be dim. I think most LED Test lights only load the circuit to about 15milliamp so my test light pulls about 4 times that and is still computer safe. I'm not even sure a LED Test light will turn on with a 5v circuit but my test light does, which you will see tomorrow in part 2.
@ thank you sir for your service
FC keeps ppl like you me is business. Yep I would say PCM. I cloned many of them.