It Almost Looked Like a Bad PCM But Its Not! Part 2 of the Jeep Grand Cherokee
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- Опубликовано: 25 дек 2024
- When I ended part 1 yesterday it looked as if the issue could have been the PCM but there is more testing that can be done. Sometimes Manufactures don't make things that easy on us and we have to dig and do extra research to find the information that could make this diagnosis much more efficient if they would just give us all the information in an easy to find place
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Nice diag and repair, Jake! I like the non intrusive testing from the PCM connector 😁👌
You have a correct and reliable diagnostic process. I learn from you all the time. Thank you for sharing. You are a champion.💙
I would give 5 thumbs up for this diagnoses if I could.
👍👍👍👍👍 here ya go, best I could do.
Really great place to bury that harness with the heat and a badly located oil pressure sensor.
Thanks for the video Jake.
I have been watching people test the 5 volt Ref for years and only ever seen them keep the circuits connected and go around disconnecting one at a time till the 5 volts came back and called it a bad sensor and if it never came back then they risk replacing the Ecm. This video has just shed light on me and given me a new way to be sure if a sensor or circuit is shorted before calling a Ecm.
Great video
Thanks heaps.
PS: I guess I have been lucky as so far unplugging sensors has got me through and I have never had to call an Ecm. But....... Now i can be certain if it gets to that point.
The other thing that comes to mind is that your not disturbing the wires by unplugging sensors which obviously could lead you astray if the wires are disturbed
Loved it.
Another great diag
Nice of the manufacturers to make wiring insulation out of oil soluble garbage that rats love to chew on. I run into this on a regular basis. Good job sir.
Great diag Jake! Very methodical! Great conclusion 👌 Jake, Ivan and Eric. You guys Rock!
Great job Jake! It's so easy to just throw the parts cannon at it, but constantly questioning our methods is the best way to come up with a solution.
I've seen this wiring issue before on the Commodores we have here in Australia. I did one recently where the oil travelled up from the oil sender as well as the VVT sensors and actuators and created a huge puddle of oil in the ECU connectors. It took out an injector driver and I had to replace the ECU.
Keep the videos coming! 😉👍
Nice diag Jake! You know I never thought of testing each sensor resistance to ground through the module connector, but if it lives in a hard to get to place it is a great process. Definitely a valid test as you have just proved! Makes you feel much better when removing that intake manifold.
Excellent video and thank you for this one!
Great diag! Must have felt good finding those crusty bare wires instead of throwing a PCM at this thing and having the problem remain.
Imagine being a fiat dodge/chrysler technician at the dealer and having to build these 5v circuits in your head all the time - and its under warranty so you get paid minimum wage or nothing to do it.
Glad I got out of the dealer scene in 2023. Wish I'd done that 8 years ago. We enjoy your content man! My new job is purely doing diags just like yours (the "hard" ones other guys didnt do or couldnt do) so im gonna start watching a lot more!
You are a professional, I have never seen an easy way to test with an ohm meter to determine exactly which sensor is which, and I watch 90% of you tube videos, they all turn off the sensors one by one to determine which ones are short circuited, I hope one day I will be a major at 50% like you, now I will be satisfied with myself, thank you
Someone in part one mentioned something about the oil sensor, sometimes running onto a problem before it tab's help but either way I never thought of checking for pcm shorted to it's own casing, although I'm not a mechanic I enjoy watching your vids that keep this old man occupied. Thanks for sharing
Yes someone mentioned this except issue!
Jake, that Jeep sure sounded nice once you were done with it. Thanks for Sharing! 🙃🙂
Well done Jake!! I know that a lot of 3.6L Pentastar engines are having the oil cooler leak issues that have to be fixed! One shop I visited said they do 4 or 5 a week continuously! It would be interesting to check with some shops in my area to see if that wiring harness needed to be replaced during the cooler repair process. I think the wiring harness issue would get more severe depending on how long the oil spill at the cooler is be allowed to contaminate the wiring.
I really like your thought process. What would we do if the new module did not fix the issue. Yup! thinking out of the box. Excellent.
I feel your pain on the Dodge/Jeep schematics. I was chasing a shorted 12v pcm output (blowing a pcm fuse), on an '11 Grand Caravan last week. I knew it was a 12v output, but which one? They sure don't do a very good job of labling their outputs. Mine wound up being a shorted oil pressure contol solenoid.
Enjoyed the video Jake, keep 'em coming.
Nice video and diagnosis. I had my money on a shorted out sensor and would have started unplugging them one at the time. Seeing that harness brought back memories of working on my 90’s Mercedes cars that had wiring issues.
Great diagnostic and repair! My initial call was a problem inside the PCM plug, but this could extend to the full length of the wiring (I should have re-watched the previous video, to see why I mentally excluded the wiring, but I was a bit lazy). Thanks for another excellent video, Jake!
Awesome diag! You didn't just condemn the pcm but went the full inspection to find the real cause.
Fantastic video harness is definitely on the list for oil cooler replacement 👊🏻👍🏻
Nice job Jake, Got the same thing going on with the APP 2 Vref coming and going on the same YMM right now. Pretty sure something is pulling it down.
Interesting case, thanks for sharing
Another great diagnostic. Thanks for sharing.
Now that was really really good !!!! Great vid.
I wonder what the extrra cost would be to use polypropelyne tubing instead of all that tape and split loom tubing to run wiring through--especially in hard to get to places like this. We used stuff called 'polytuff' to run small wiring on heavy machines. Use marine grade heat shrink at the base of the electrical plugs and the end of the tubing to make a complete seal. Polytuff is even flame resistant. Would save a Iot of headaches down the road. I know--headaches are not the concern of the OEMs.
Excellent trouble shoring , thank you
Awesome Jake you are the man!
Test test don't guess .
Very strange that it did not set an oil pressure sensor code.. Back in video #1, .it did set an OIL pressure history code..,but you did not click on it to find out more. Any codes that show up could be a clue on where to look.
So if that oil pressure sensor had 3 wires then it probably has a normal range.., maybe like .5 volts to 4.5 volts... When shorted it was probably at one of the values outside normal. The pegged high pressure on the dash oil pressure was a definate clue. Great diagnostic.
Exactly what I thought and have seen several times.
Thanks !
Outstanding stuff !
Much appreciated !!
Had a Chrysler (Jeep) ECT sensor that was bad inside of the connector itself. I had to borrow a ground off the MAP sensor. Had resistance about 1/2 inch up from the ECT connector but not by touching the pin (front or back). We used a Mopar pigtail.
Jake, what I can’t understand, what would make you think of a sensor short to ground and sending it through the ECM, that is some brilliant thinking. My hat off to you. Love it. 😅
Short to reference ground, not chassis ground. And of course the short to chassis ground went away when the PCM was unplugged Tricky!
Wow. Great job. 👏
Nice repair and find Jake . Maybe when we saw 100 psi on the dash readouts it should have rung my bell . Really have not seen any cars with 100 psi oil pressure . Thanks for the updates Artie 👍
That just happens to be the max the sensor can go so it's a tell tell
Wrong! You didn't see post-fix start-up hitting 99psi with partial throttle-blip?
@@grad0n that’s a cold start and it’s in high pressure mode. It also started out saying 0 psi where before it said 100 with the engine off. So not really sure what you are saying is wrong?
Good job. 👍
I have gotten those filter housings from Chrysler with new sensor and it be bad. I always reinstall the original sensor if it doesn't have a problem.
Great fix Jake!.
This is the exact type of electrical understanding that is lacking in the industry. It’s also part of the next class I’m going to write.
PJ keeps telling me I need to write a class but I don’t know where to start or what to cover lol
Very good video thank you for sharing
Keep up the good work ❤
Thank you for the knowledge and video
Great video series!
Following you from iraq
I love your vids have a cool info
Same goes for misfire monitors. Not all manufacturers give you live data for misfires and to me this is irritating. We all have methods for figuring it out regardless. But it's obvious the pcm knows which cylinder is misfiring because it will eventually throw a code for it. But even that sometimes is irritating because you'll get a P0300 for a single cylinder misfire. Any case just let us see which one is misfiring so we can get to why sooner. Instead of going through whatever it takes to get to the point where we know exactly which cylinder is misfiring.
Awhile back had a GM truck which was clearly misfiring yet the misfire counters would not show it. Would not even set a current P0300. I thought i was imagining it and said to my foreman to put his hand on top of engine. Yup its a dead miss. I know but look at the data. Turns out if fuel level is too low it would not set a current code or count misfires. Added fuel to it for a road test and counters started to count misfires. Just some info in case you run into this. Had me confused for a little bit.
@jeffco908 Good info. Thanks brother.
Good call
She deserves respect 🇮🇶🇮🇶
good fix
Great diagnostic..hats off to you🦾
Amazing diag.. Jake
PCM circuit design has multiple grounds all, except chassis ground, connecting at a star point, or star plane, usually comprising of the following; Digital Ground, Analog Ground (includes SIGRTN), Power Ground, and chassis (also call case) ground. Power ground to chassis ground connection on the PCB is usually not a direct short. The connection is made through a capacitor in parallel with a resistor at several places around the out side periphery of the PCB, whos final values are usually determined during preliminary EMC measurements or circuit analysis. If in the end the PCM team wants a direct short between the power and case ground they can specify a surface mount zero ohm resistor, which is just a shorting jumper.
If you want to know if a module output is shorted to ground it is best to use a power ground pin on the connector as reference and not the metal case.
The PCM design teams are usually very experienced and so there is a pattern as to how PCM circuitry is designed. With +5VREF there is usually a dedicated regulator stage of some type, which will protect the output form shorts to ground, shorts to +12V, overcurrent, ESD, etc. It is very difficult to damage the output given the expected failure modes of what is connected to it.
The vehicle electrical diagram approach and quality is really a function of the OEMs internal standards and the expertise of the vehicle team responsible for harness signoff. For domestic OEMs official published workshop manuals before 2014 I would put Ford as number one, from 2014 to present I think GM is usually the best, with Ford a close second. IMHO Chrysler automotive electrical design and documentation is near the bottom of all the OEMs worldwide. Which is strange because historically the Italian auto electrical design was near the bottom of OEM quality along with the old British designed vehicles, which at first glance was just perhaps, to an open mind about such matters, an unwarranted prejudice and stereotype. But, today, once again, based on Chrysler, perhaps not?
If you bring into the room the PCM module design team and the harness design team with the OEM build engineers, which happens if there is a problem with a prototype vehicle build, you will usually find out the PCM team chief designer / engineer is presented with a problem, normally and without fail, first attributed to a bad PCM design, but in looking at the wiring approach by the OEM and the harness supplier, and how it is implemented in the vehicle porotype build, there are basic mistakes made in how circuits actually function and how the wiring is critical for proper operation. Then the whole pattern repeats when the vehicle is tested for EMC. In my experience overall system problems are never with the PCM as qualified at the prototype build phase. The PCM may be at fault overtime due to the quality of the components and high temperature operation, but not usually within the warranty period, and not in the prototype factory build.
The reason for the deteriorating harness insulation is because the harness is not designed properly for the application. The first clue is the foil covering which is crap, and the wire insulation which is also crap. For the environment of this harness the wire should be high temperature TPFE (Teflon), covered in open mesh fiberglass sleeving (the open mesh is less expensive than the coated fiberglass), with high temp heat shrink to seal the sleeving ends at the connectors. Also, with the install you have to make sure that the harness does not move with engine vibration. It may be better to use small insulated P-Clamps rather than the XMAS tree push mounts, and you will have to probably add more support to the harness above and beyond what originally came with the vehicle.
I’m glad I’m not the only person that gets frustrated by the way manufacturers makes things difficult for absolutely no reason 😅😂
I mean why do they actively try to not make electrical diagnostics efficient?
@ I feel that in my soul it’s like it’s only getting worse 😂
We can't expect the manufacturer to build that harness with silicone wires resistant to oil. I would pay the extra for the protection.
Your scan tool's pre-repair analysis showed an issue with the oil pressure sensor in your first video. It's definitely challenging to determine right away if that is related to the TB problem or a different one altogether, especially without the thorough tests you conducted. Did you think it was unrelated at the first glance of the code scan?
At first I was unsure because I knew the had replaced the sensor, along with the crank sensor and both cam sensors. So since it said history instead of current I honestly didn’t know.
1:55 internal short within a connection ( green booger) or sensor itself
Great video Jake fine diagnostic work.
Good job!
Nice!
14:20 Everything is needed are silicone insulation like on heaters, furnaces, etc...
I'm guessing the tech pinched a wire when changing the oil cooler.
Not sure at what point in the video you made this comment but no it didn’t have anything to do with the mechanic that put the oil cooler in. This car was actually having this problem intermittently before the oil cooler was replaced.
Are you doing the resitance with battery disconnect
No but I would highly suggest it to newer techs until they fully learn and understand the circuits they are testing and how stray voltage can give false reading.
Good 👍
You beauty jake 🎉🎉🎉🎉
oh yes i feel that pain . our older drawings you could click on the splice and it would list out what ever else was on there also click on the connector and it would take you to the location . new ones oh no none of that and to top it off new ones give you a description of the block as in body to body or body to facia but no terminal block number . oh no for that you have to use another drawing . man i tell you that boils my p*** . great example there my friend of thinking outside the box or you could be eating a £1000 ecm 😱😱😱
that was a good one!
I was just told in order to fix a p0303 that I needed to replace the PCM on my '12 WK2 5.7 Jeep GC. Recently, I had the radiator, battery, starter and all 16 spark plugs replaced. The shop did a #3 cylinder compression test, and moved the ignition coil, but the p0303 code's still there. My fuel mileage has gotten really bad too. There's also an oil leak from the oil pan gasket, and oil seeping from the valve cover. Before I pay for a new PCM I need to see if there's another issue. A p0303 means the problem is exclusive to the #3 cylinder, right?
I wouldn’t trust a compression test on that engine. A failed exhaust lifter could still give good static compression readings. A relative compression test would be much better.
Thanks, not sure what compression test they ran. They also ruled out the #3 injector. Said it worked, but it’s not getting spark from the ecm (I said pcm earlier). They did say they couldn’t guarantee a new ecm would fix the problem, but that they’re sure that’s the culprit.
@@friskywildthing if the “spark test” was moving the coil and it worked on another cylinder and #3 was still misfiring that doesn’t verify anything other then it’s a command issue with cylinder 3 or a mechanical issue with cylinder 3. I’m pretty sure on that vehicle if you unplug the #3 coil with the engine running it will set circuit fault for the coil. If it does that then it’s extremely unlikely the pcm is bad or there is a wiring issue. Search for a video on relative compression. You can do an audible one yourself and hear if you have a compression problem.
@@autodiagyt Thank you! This is really helpful. I think that's what they did, moved the coil to another cylinder. Yesterday I decided to have them order another ecm. They said they'll order a Mopar to be certain they're getting the best quality part. I'll look into relative compression and ask them which test they did.
@@friskywildthing If they're sure that's the culprit, then they should have no problem giving you a guarantee. That's a pretty easy issue to diagnose (P0303), so I'm surprised a shop is saying that.
👍👍👍👍 nice
So oil and gas resistant wire cost too much for the factory to use?
Jake I hope it's not silly question....why u didn't get the short while u check the short in 5v in part1.. Is not the same 5v for all sensors???
The short “appears” to go away when the pcm is unplugged. What most techs and even service info miss alot of times is the short to ground doesn’t have to be to the engine block or something else. The short could be to a low reference ground wire that has to travel through the pcm before actually connecting to chassis ground.
Is the computer case a ground
It is "bonded" to ground yes but not designed to be the ground.
Chrysler bad 4 looped and shared grounds
If it's a Jeep, it's usually a short or bad ground. lol
❤❤❤❤❤❤❤
A Chrysler without the dreaded red locking tabs
Ill never understand why the oil pressure sensor isn't on its own isolated circuits. GM does the same thing. I've had multiple GM trucks crank no fire because of the oil pressure sensor taking out half of the entire system. Some of the designs the OEMs come up with are nothing but a clown show.
Bad 3rd brake light bulb 💡
?
"These harnesses are not that expensive." $150 bucks!!! WHAT?! If that wire insulation is breaking down from oil saturation then it should not cost anywhere near $150. It means they are charging you for the more expensive automotive or marine grade wire but giving you the cheap plastic insulation wires.
PTFE insulation is what I was thinking of. Wire with PTFE insulation is what you would want in the middle of the engine like that.
That diagram wont even show all the shared circuits. that 5volt shares with all kinds of shit. The oil pressure sensor that is aftermarket is a common 5volt short on Mopars.
Great video, another garbage Jeep....really good video.
Wrong. "If they still do not want new harness", do NOT "get rid of them". Instead, keep them even CLOSER to your heart because when they come back with this problem, you will show them your warning written in the past and will sell them all this "disassembly work" time. Very expensive. Very good for business, for your wallet, for your soul, for your heart. Ask your cardiologist. To rephrase, "keep your friends close, but your enemies - closer".