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  Topic Review (Newest First)
02-16-2019 09:47 AM
Chris24 I have a 2004 Jeep Cherokee 4.7 and just replaced the crank position sensor which was a pain and still getting similar problems. The car starts and runs with no key light on when starting, then once the car is running for 2-3 minutes, the key light comes on and the car either stalls right when the key light turns on or it just keeps running fine. The guages work fine when parked, once you start driving they all flicker on/off. Getting 2 codes, p 0443 and p 1865, which is bad Evap solenoid and not reading key correctly (even though I have one original key and two new oem keys that were just programmed “correctly” supposedly.) any ideas? Should I go to the Jeep dealer and just get all the three keys programmed? Oh yeah and the SKIM is fine bought a new one then was told the old one is fine.
10-09-2018 11:44 PM
DESERTRACER Well good luck with this problem. I have to get back to making the plugs for the new fiberglass hood and fenders for the WJ and machining the new big bore throttle body for the 4.7L. see you later.
10-09-2018 10:50 AM
kdubbs46 Thanks for staying on @OldWJs . If it comes down to it, i'll definitely take you up on your PCM offer.

Update...The WJ and I were arguing so I didn't go near her for a week.
Yesterday for giggles I went out to start her, and lo' and behold she started first try. All gauges active, no CEL, no skim light.
Let her run idle for 20 minutes. Went out to move her and hit the throttle while getting in. The second I touched the gas all gauges went dead again...but she still ran (perfectly, as usual) and I was still able to move the vehicle to another part of my driveway. While running I pulled both the driver's side plug and passenger's side plug, with no change to the gauges.
Next, I turned her off, waited 5-10 seconds, then turned her back on. Started perfect, ran perfect, no gauges functioning, skim light on. Waited for the inevitable 3 second stall....aaaaaannddd (despite the skim light being solid on)........she kept running.
As always, any input is appreciated!

Going to try the steps in this thread as soon as I can.
https://www.jeepforum.com/forum/f310...olved-1339353/
10-08-2018 07:17 AM
OldWJs
Quote:
Originally Posted by Mattyjm View Post
I have a buddy who called me last week with this problem in his 2002 Limited 4.0L i6/42RE/242 T-case with 280K on the clock. His gauges went dead and his SKIM was keeping the Jeep from running. After a little conversation, I told him I thought his PCM was bad and sent him a link to a good one. He has free roam of a junkyard near his house and decided to go have a look. What I'm about to say next is information of EPIC proportions....

Like I said before, he has a 2002 Limited WJ with the powertrain that I mentioned. He pulled a PCM from a 2003 Laredo, 4.0L i6, 2WD model. No programming, no matched VIN, no part number match... The junkyard PCM got his gauges working again, but it was still shutting down after three seconds. I told him to go get the SKIM, ignition cylinder, and master key from that same 2003 WJ and see if it works. IT DID! He's driving his 2002 Limited WJ today with a PCM, SKIM module, ignition cylinder, and master key from a 2003 Laredo 2WD WJ. That's new information, I believe, on this forum. I hope this helps someone some day.
I agree, PCM certainly can cause this issue, and if swapping another used PCM, SKIM, lock cylinder and key in that all match is an option for you, it's certainly something to try:

Quote:
Originally Posted by OldWJs View Post
So, the conditions that will cause the “start but shut off in a couple of seconds” are:

1. Key ID doesn’t match one of the IDs programmed into the SKIM. This is actually the behavior that the engineers intended – i.e. if the lock cylinder is picked and turned or overcome in some other way but one of the correct keys is not used, the vehicle won’t continue running – in an attempt to prevent theft.

2. Bad SKIM (extremely, overwhelmingly uncommon. This is just something you don’t hear about)

3. Bad PCI wiring somewhere in the vehicle (very common especially at high miles and in corrosive wet climates).

4. PCM VIN programmed does not match SKIM VIN programmed (PCM not programmed to match after replacement/swap)

5. PCM failure to master/manage the PCI bus (this would be accompanied by other PCM issues, specifically stalling while running, likely because of failure of a voltage regulation portion of the board)

Like I said before, if it starts and then shuts off, it’s possible and likely to be bad PCI wiring.

Point is, there are several things that can cause this condition. Do NOT jump to the conclusion that you have a bad PCM without understanding the other things you will likely see if that’s the case, and eliminating bad wiring, etc. Yes, it can be the PCM, but without other problems, it’s probably something else.
If your only option is to order one of those "rebuilt" units to try, I was trying to make clear that you should first make sure your PCI wiring is good first, or you could compound the problem with a PCM that has problems if your original one didn't.

It sounds like there have been at least a couple of cases where PCM replacement fixed the problem. I will admit this is a little different failure mode than I have seen before, in my experience usually when the PCM does this you'll get the hot stall condition too and it won't start at all. So, really interesting, useful information. As these get older, we'll likely see more types of failures. The newest ones are 15 model years old and the PCM design had weaknesses to begin with.

I'm sure as many of you have found in other posts, I do have a tool that can program the VIN, and a good local u-pull it where I can get used PCM's - and I'm in a cool climate where we tend to see less failures. My cost for a used PCM is about $46 and I can usually ship them for between $10 and $20. If anyone needs, I can go pull, program and mail a matching PCM if there is one available. Cover my cost and shipping. If it doesn't fix your problem, send it back. If it does I'd want to work out with you something additional to cover use of my tool, programming harness, and my time spent going to the yard to pull. I've already done this for a few people on here with good results.

It's occurred to me numerous times, that for people who restore old cars, it's always possible with enough money and time to make a 50 year old mustang, camaro, dart, whatever, run. What's it going to be like in 50 years for these computer managed vehicles? At the very least PCM repair, or replacement with a customized engine management solution is going to add a lot of complexity to getting your old show car to run!
10-07-2018 09:47 AM
Mattyjm
Quote:
Originally Posted by OldWJs View Post
It's too bad you don't have another PCM, SKIM, lock cylinder and key all as a set to swap in to just try.... Something like this available in a junkyard nearby?

I still think it's PCI bus somewhere in the vehicle but that can be hard to find.
I have a buddy who called me last week with this problem in his 2002 Limited 4.0L i6/42RE/242 T-case with 280K on the clock. His gauges went dead and his SKIM was keeping the Jeep from running. After a little conversation, I told him I thought his PCM was bad and sent him a link to a good one. He has free roam of a junkyard near his house and decided to go have a look. What I'm about to say next is information of EPIC proportions....

Like I said before, he has a 2002 Limited WJ with the powertrain that I mentioned. He pulled a PCM from a 2003 Laredo, 4.0L i6, 2WD model. No programming, no matched VIN, no part number match... The junkyard PCM got his gauges working again, but it was still shutting down after three seconds. I told him to go get the SKIM, ignition cylinder, and master key from that same 2003 WJ and see if it works. IT DID! He's driving his 2002 Limited WJ today with a PCM, SKIM module, ignition cylinder, and master key from a 2003 Laredo 2WD WJ. That's new information, I believe, on this forum. I hope this helps someone some day.
09-29-2018 09:02 AM
Fracture Had my gauges do this every time I started my Jeep. This was after replacing my PCM with a custom one where I had them disable the SKIM all together. I ended up warrantying my PCM for another one and haven't had an issue.
09-29-2018 08:16 AM
Ognik This just happened to me... yesterday, when I moved my jeep to change the wheels, I noticed the SKIM (bad key light?)on.. I was using the spare key and thought it might have caused it. After changing the wheels when I fired it up all the gauges went nuts, turning on and off and all the warning lights (low fuel, ABS, check engine,etc) stayed on and gauges shut off. The engine was running fine and I went for a test drive (dumb). Fortunately, I was able to drive a couple miles and make it back home in this condition. But when I parked it, I wasn't able to put my driver window up and my power seat was not working, passenger window and sunroof worked. I was able to start it up one more time to move it into the garage where it now sits.

I've had a water issue where I've found my driver side floor carpet soaked after driving and parked out in the rain. The sunroof drain is fine but I found a rust hole in my wheel well and I thought that might the source. My drivers door panel is loose, probably from broken clips after I changed the window motor years ago.. could this be the location of all these problems? I also noticed my automatic lights didn't turn on as usual when I pulled into my dark garage... is this related? I should start by looking for water inside my door wiring and then check the wiring under my driver seat?
09-27-2018 03:42 PM
kdubbs46 Thought I gave up didnt you!
Well....I'm close to be honest.

I found this link (similar symptoms to mine)
https://www.jeepforum.com/forum/f310...odule-2328385/

and in it this:
"Did you measure the Voltage at PIN 2 on the data port (Scan tool port). This is the BUS communication circuit. It is what all the other modules talk to the PCM over. If there is a problem with one f the other modules this is most likely where it will show up. With the key on it should fluctuate (between 0.2 to 2.0 volts I think) If it is like 6v or higher there is a problem with a module somewhere. If there is no voltage, you have a open circuit somewhere, possibly in a module or in the harness. "

I measured the voltage and when turning the key to the "on" position the voltage bounced up to about 2.3, then back down to the tenths.

Is this an effective way of checking for a bad module and/or open circuit?
If so, it appears that my test passed the....er.....test, and I have no bad module, and no open circuit, and therefore a bad PCM? A new PCM was the OP's fix, btw.

I have yet to source a PCM, SKIM, and matching lock cylinder. Being on Long Island with a few junkyards in the area, this may be possible.
If i am sure it is the PCM, I think I'd rather buy a remanufactured/rebuilt one that is pre-programmed. Any thoughts on that, too?

Thanks guys.
09-23-2018 07:23 PM
OldWJs
Quote:
Originally Posted by kdubbs46 View Post
Update....
Appeared to be starting and running well so I decided to do some preventative maintenance.

Disconnected battery and pulled the 2 large plugs above the PCM. Their wiring headed back between the engine and the firewall. They were quite dirty and looked as though they may be getting some runoff from behind the hood and driver and passenger plugs (figuring they were the most likely place to have water infiltrate.
Dinner called so i cut the process early.
Connected everything back together and we are back to the SKIM light being on, off then back on. Perfect starts, then back off after 3 seconds.

I checked the codes again and something kind of strange happened. It displayed p1687, then a slight delay, then - - - - - - - . Never displayed "done".
Please help!?!

Thanks again all.
It's too bad you don't have another PCM, SKIM, lock cylinder and key all as a set to swap in to just try.... Something like this available in a junkyard nearby?

I still think it's PCI bus somewhere in the vehicle but that can be hard to find.
09-23-2018 07:19 PM
OldWJs
Quote:
Originally Posted by DESERTRACER View Post
It is near impossible to tell you where the problem is without physically laying hands on the vehicle. all we can do is give you some advise, places to look, and what worked for us.

I replace NO parts before I find what the problem is first.
Agree 100%. Obviously you did thorough and proper diagnosis, but I just wanted to make sure we don't give the impression to anyone else reading this that they should just replace the PCM without first making sure the root cause isn't something else... I've spent a lot of time on here answering "It's the PCM" in cases where it's clearly the PCM but what all three of these folks are describing is something that may very well not be the PCM - and I don't want anyone searching and reading this and compounding their problems! A full and *correct* understanding of how this stuff works is crucial to the diagnostics process and there is so much misinformation on the Internet - I've spent so much time breaking and fixing these and gaining a detailed understanding, that I want to help by posting clear, detailed and correct information ....
09-23-2018 02:12 PM
ezflip Im with OldWJ on this one. When this, almost exact same situation, happened to me I didnt have time, nor another vehicle to troubleshoot myself. I had it towed to a dealership and they found a short in the PCI bus wires going to the BCM. $130 later, the problem was fixed and I was on my way. Not a bad price, IMO, for the stealership to troubleshoot a short in wiring.
09-23-2018 01:44 PM
DESERTRACER OldWJ does bring up items that need to be checked. I was trying to simplify the possible causes with out getting into the complete diagnostic procedure. OldWJ, no fight pickin feeling here. All is good.

The way I find my problems is list ALL the problems on a sheet of paper, then look for 1 common link that connects those problems together, in my case the connections were the PCI bus wire and the PCM. no other items make a connection to the problems that i was having. Since i narrowed it down to the two items, i tested the "hardest to fix item" and found that the PCI bus was fine. At this point, the first thing you replace is the easiest one to get to and the only thing left, the PCM. So in my case, there are not any issues that are here today gone till tomorrow. All issues are fixed.

It is near impossible to tell you where the problem is without physically laying hands on the vehicle. all we can do is give you some advise, places to look, and what worked for us.

i own 3 1999 GC limited's, the only thing different is the paint color.
I'm the "chief mechanic" for my younger brothers 1999 GC. (This one is getting a newly rebuilt 2012 Dodge Ram 310HP+, 4.7L as we speak. I'm making all of the modification to get this to work.)
And the personal mechanic for my daughters 2007 liberty.

I replace NO parts before I find what the problem is first.

With all of these Jeeps in my stable, the red GC is the only one that I have had to replace the PCM on. Since the first replaced PCM, ALL are A-1 CARDONE units from my local NAPA, I have replaced 5 units, all under warranty, over 4 years, all with completely different issues, #1) no 5 volt dc signal out, #2) no PCI Bus signal, #3) no CKP and CMP signal, #4) engine dies at stop and while driving but restarts, and #5) the one i talk about earlier here. One "REBUILT" PCM lasted 2 days and one PCM lasted over 2 years. In all of these problems , I diagnosed the problem to located the issue first, then replaced parts. None were miss diagnosed. That is why i'm looking more to the PCM.

As far as the PCI Bus wire my be the problem? I agree, it needs to be looked at. But the PCM is still a suspect. To eliminate the possibility that the "PCI Bus wire may have water" issue within the front doors, Disconnect the door wiring harness before the wiring harness enters the door from the main wiring harness. then see if the problem is still there. If the problem remains then that eliminates the door modules and the door wiring.
09-23-2018 09:13 AM
OldWJs I want to be clear, I’m not trying to pick a fight and I appreciate everyone’s input. I think it’s good to clarify these troubleshooting processes to continue to discuss.

I know I’ve often condemned PCMs in posts here, let’s face it, there are several common failure modes with them and they DON’T fit the usual “over 90% of the time engine management problems are incorrectly diagnosed as the PCM” narrative.

But there are other failures to be discussed here and I want to make sure people don’t jump into the PCM replacement route without being sure that everything else is in order. If you replace with a “rebuilt” PCM in a case where your original is just fine, you may be compounding the problem, if the “rebuilt” is a piece of trash like they are more often than not. And even if you do get a good replacement, you’re spending a substantial amount of money that you didn’t have to.

Quote:
Originally Posted by DESERTRACER View Post
This is a signal that originates and is sent from the PCM to the gauge cluster and the DRB Connector. if your not getting the "DONE" message that's the PCM. <BAD PCM>
Yes, AND/OR the PCI bus has a problem. Especially when it doesn’t crap out while you’re driving it if you do manage to get it started and keep it running after the first few seconds.

Quote:
Originally Posted by DESERTRACER View Post
P1687.....No MIC bus message... No CCD/J1850 messages received from the Mechanical Insturment Cluster (MIC) Module
Yes, if the bus is working well enough that the cluster can read that code out of the PCM. Kind of a chicken and egg problem.

Quote:
Originally Posted by DESERTRACER View Post
In order to trigger a DTC and the MIL light, the PCM has to see the exact SAME condition for 3 cycles. If the issue is NOT seen for 3 cycles, the PCM will turn off the MIL light.
You’re talking about pending vs mature DTCs. Many scan tools will read pending codes too. They’re set and can be read before the MIL is turned on.

Quote:
Originally Posted by DESERTRACER View Post
SKIM light on but the jeep still drives?
The SKIM module will not allow the PCM to start or run the vehicle if it does not "READ" the proper chip key. This is the default setting of the SKIM, NO CHIP< NO START. If the SKIM module is bad or a BAD SIGNAL from the SKIM, onto the PCI Bus to the PCM, the PCM can not start or run the engine. since it runs, the SKIM has to be good. So when the gauges go dead and the SKIM light is on, AND the jeep is running, the PCM PCI Bus signal going to the instrument panel is "BAD". The instrument panel is not getting info. <BAD PCM>
Or bad wiring, in many if not most cases. You have the general idea but there are a few things here that are not quite correct. Hear me out. Sorry for the wall of text.

With WJs or any other JTEC managed vehicle, the vehicle will START but will not continue to run if there is a failure in the SKIS system. A bad SKIM will NOT prevent the vehicle from starting at all, it will only cause it to not CONTINUE running, immediately after it DOES start. If I understand correctly, your vehicle got to the point where it would not start AT ALL. I address this later on in the post.

Here’s how it works. The PCM manages the PCI bus which is necessary for the PCI bus to work at all (https://www.searchautoparts.com/moto...i-bus?page=0,0). This is kind of like the function that the CAN bus gateway performs. The PCM has to be working properly for the PCI bus to work between the other modules in the vehicle. As an aside, PCI in this context has nothing to do with the PCI peripheral bus commonly found in desktop and laptop computers. It’s a coincidence that Chrysler picked words whose acronym is PCI. It’s formally defined as “SAE J1850 VPW”.

The setting for whether the PCM needs to see the message from the SKIM is actually in the PCM. It is actually possible with some aftermarket tools to turn the SKIS function completely off (
).

The only thing programmed into the SKIM is the VIN and security PIN (both are one time, permanent), and IDs from each of the keys that it will accept (modifiable using an advanced scan tool, which requires you to know the pin unless you have an aftermarket scan tool that has some tricks up its sleeve). On startup, the SKIM reads the ID from the key, and if it matches one of the IDs in its memory, it will send a message including the VIN over the bus to the PCM.

If the PCM doesn’t see a message from the SKIM, with a VIN that matches the one that has been programmed into it, within a couple of seconds after start, it will stop the engine. If this is the case the key light on the dash will be lit after the vehicle stops running.

It’s important to understand that if the PCI bus is lost at some point after a successful startup PCM/SKIM handshake THE VEHICLE WILL CONTINUE RUNNING. This may be a side effect of how the system is designed, or possibly deliberately designed into the system for liability reasons. The fact remains that, if the vehicle shuts off after the first couple of seconds of running, it has nothing to do with SKIS.

So, the conditions that will cause the “start but shut off in a couple of seconds” are:

1. Key ID doesn’t match one of the IDs programmed into the SKIM. This is actually the behavior that the engineers intended – i.e. if the lock cylinder is picked and turned or overcome in some other way but one of the correct keys is not used, the vehicle won’t continue running – in an attempt to prevent theft.

2. Bad SKIM (extremely, overwhelmingly uncommon. This is just something you don’t hear about)

3. Bad PCI wiring somewhere in the vehicle (very common especially at high miles and in corrosive wet climates).

4. PCM VIN programmed does not match SKIM VIN programmed (PCM not programmed to match after replacement/swap)

5. PCM failure to master/manage the PCI bus (this would be accompanied by other PCM issues, specifically stalling while running, likely because of failure of a voltage regulation portion of the board)

Like I said before, if it starts and then shuts off, it’s possible and likely to be bad PCI wiring.

Point is, there are several things that can cause this condition. Do NOT jump to the conclusion that you have a bad PCM without understanding the other things you will likely see if that’s the case, and eliminating bad wiring, etc. Yes, it can be the PCM, but without other problems, it’s probably something else.

Quote:
Originally Posted by DESERTRACER View Post
I live in the Desert Southwest, no rain, no humidity. But I had the same DTC code, engine would die while driving but would immediately restart-run-drive, engine would die sometimes when applying brakes and/or stopping but starts right up, same dead instrument cluster, intermittent gauge(s) working or not working, intermittent A/C clutch operation, SKIM light on but engine starts/runs, SKIM light on but no start, all of these issues had one thing in common, PCM. <BAD PCM>
In your case, yes, absolutely. “engine would die while driving but would immediately restart-run-drive “ is a very common PCM failure mode that has absolutely nothing to do with the SKIS system or the bus. Your failure mode was a failure in the PCM, leading to the PCM failing to function, including its bus management function as well as its main engine spark and fuel management functions. The bus went away, and enough of the board was apparently still working to register the appropriate DTC for the bus having gone away. Nothing I’ve posted above makes the assertion that this can’t happen.

Quote:
Originally Posted by DESERTRACER View Post
I replaced the PCM after 2 weeks of issues, when finally the SKIM would not allow the truck to run.
Without being able to personally diagnose and test, I can’t say for sure, but I strongly suspect that the PCM is what finally failed to the point where the vehicle wouldn’t run. It wasn’t the SKIM preventing it from running. This is very common. I know I’m kind of nitpicking small points here, but I think it’s very important for people to understand the distinction when they’re trying to do their own diagnosis based on what’s written here.

Quote:
Originally Posted by DESERTRACER View Post
NO MORE PROBLEMS.
Fantastic, and these problems can be just miserable to get ironed out.

Quote:
Originally Posted by DESERTRACER View Post
While you may have a water issue in the drivers door, only the Driver Door Module is in the door, but do the driver side door controls the other door(s) window and locks?
Here’s how I think it works, and this is based on my having connected to both the DDM (driver door module) and the PDM (passenger door module). The DDM controls both front and rear driver side windows and locks directly. The PDM does the same for the other side. I’m basing this on the fact that you can read amperage values necessary to run the window motors in real time, for both driver side windows, from the DDM, and likewise for the PDM.

It is my assumption that the DDM commands the PDM to roll windows up and down, and lock or unlock on the passenger side over the PCI bus. Pretty sure the DDM requests the PDM to actually perform the operations requested when the driver manipulates controls on the DDM that affect the passenger side.

All of this is kind of beside the point. The fact is the PCI bus runs out to both front doors, and it’s a common place to start troubleshooting PCI bus wiring faults, because of the fact that the wiring flexes at the door pillar and the wiring in the door is subjected to more movement and shock over the life of the vehicle – this is usually, BUT NOT ALWAYS, where the PCI bus wiring fault will be found.
09-22-2018 06:33 AM
kdubbs46
Quote:
Originally Posted by GhostJeepWJ View Post
@DESERTRACER Thanks for taking your time and being so thorough and detailed with the info.
Posts like that are what makes the forum great!
I cannot agree with this enough...
Thank you @DESERTRACER @OldWJs @GhostJeepWJ

If not for this forum I probably would be broke! Sure the 4.0 and 42re are bulletproof but it sure seems like nothing else is on my WJ!
09-22-2018 05:04 AM
kdubbs46 Update....
Appeared to be starting and running well so I decided to do some preventative maintenance.

Disconnected battery and pulled the 2 large plugs above the PCM. Their wiring headed back between the engine and the firewall. They were quite dirty and looked as though they may be getting some runoff from behind the hood and driver and passenger plugs (figuring they were the most likely place to have water infiltrate.
Dinner called so i cut the process early.
Connected everything back together and we are back to the SKIM light being on, off then back on. Perfect starts, then back off after 3 seconds.

I checked the codes again and something kind of strange happened. It displayed p1687, then a slight delay, then - - - - - - - . Never displayed "done".
Please help!?!

Thanks again all.
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