Hello new to the forums,

Got a 94 Grand Cherokee that died today and wont start back up.
For the past 3 weeks been having a issue with it dying while driving, there was no certain rpm range, time or speed that I noticed. Typically after it shut off I could wait 5-10 seconds and she would start back up and drive normal and I would finish my trips (which were typically 1-2 hrs). The only thing I was able to find constant was before it would shut off the rpm's would drop to about 200ish when in idle, only noticed during around town driving. It died on the highway once and I didnt notice a lost of power, minus it shutting off, or any kind of rough running it just died. I first changed the CPS and she still died then cleaned the TB and IAC which seemed to fixed the low idle issue but it would still randomly die, so I swapped the IAC with a new one and that had her running good for a couple of days, then she died today and it took longer to get her started than usual and she shut off 2 more times, roughly within 10 miles, before getting to the house, where as before she died and when I got her back on she would run the rest of the day. Prior to today the only codes she threw were 12 (memory standby power lost, battery or computer connection lost) and 55 for the end of codes, this time had the 12, but also 62 ( EMR mileage cannot be stored in EEPROM or PCM failure SRI mile not stored, according to what I found on forums for the Cherokee) she hasn't started since I got her home. I am concerned with the power/computer disconnect code with the pcm code. Could it be a bad pcm? anything a shade tree mechanic can check or troubleshoot? I know how to turn a wrench but not what to troubleshoot thanks in advance.

 

Welcome to the forum.

Please note the topic is posted in the Grand Cherokee forum, but is referencing a Cherokee, different vehicle with it's own forum.

Please seek the assistance within the correct forum.

 

I edited it and added the grand but dont know how to for the title.
its a 94 jeep Grand Cherokee with a 5.2L

 

I think your first diagnosis may be correct. PCMS die a slow goofy death. Took 4 months before mine died. Eeprom errors, etc that would come and go. Only died once while driving thought - nasty, teeth-jarring pothole.
Check all the plugs and wires to it - UNPLUG the battery first. Negative first, then positive. I was told to put the 2 cables together to bleed any errant charge. Check for heat damage. Clean the plugs, check for corroded bkades/pins. Dielectric grease to seal.
Good ol' Daimler Chrysler and their damn electrical ghosts. Been chasing BCM ghosts ever since I swapped in a new PCM.
Good luck.

 

Has the fuel pressure been measured at the fuel rail? Is it within specs?

 

Yea that was something I had checked but noticed I didn't mention, it runs at 39-40 psi which I believe is within range. I make a list of things that are in range and it was check off as good

 

Well I am not the sharpest tool in the shed but am I wrong in seeing this as not correct?
decided to take out the pcm and check on it and.....well.... you see what I seen. I'm not very knowledgeable with pcm except they are then computer that makes the jeep go vroom vroom and such

 

my 93 zj did this. I replaced cpks crankshaft position sensor which fixed the stalling part. Next my Jeep just died out while driving. It would crank but not start. I replaced the ignition coil and she starts and drives perfect. I went through checking everything like you and then got my multimeter out to find the problems.
Hope this helps! Aloha

 

Not sure it matters but I checked out the QR code and it say for installapart.com which is no longer available. anyone ever heard of it by chance?
I know the ignition system is good I did a tune up about 9 months ago and I double checked that stuff just on the off chance I bumbled something in the system, but it checked out.
But either way I am thinking of just trying a different pcm, anyone agree or disagree?

 

Note that many recommend to only use the OEM part, not aftermarket on the CPS.

Is the concern that the PCM potting is not uniform?

That is a common rework. The PCM capacitors age w/ time, temperature and absence of voltage, eventually failing.

The solution is to open the PCM, cut away the potting and replace the capacitors.

Here is my PCM rework.

 

Is the concern that the PCM potting is not uniform?

That is a common rework. The PCM capacitors age w/ time, temperature and absence of voltage, eventually failing.

The solution is to open the PCM, cut away the potting and replace the capacitors.

Here is my PCM rework.[/QUOTE]

Ok so I put that PCM back in and she started up, sat in the driveway for a little while revving and letting idle and she would randomly die, 2x at around 2500 rpm once at 3000 and 3 times coming down from a rev into idle around1200-1500rpms,
what I can tell you is a constant right now is after she dies I can get her to crank back on immediately seems after 5 mins she'll start and sputter I had to wait between 20 and 30 min for her to start and run correctly. But if I disconnect and reconnect the battery she'll start right back up. Any leads on what I should dig into?

 

In my case I suspect the issue was not fully seating that massive PCM connector after reassembly. Start w/ verification that the connector is seated, not just by tightening the bolt, to ensure it is good side to side.

 

Well I haven't made any progress with her but someone mentioned to me about the cam shaft sensor. I am thinking of getting a new one but before I do I just wanted to get another's opinion. From what I dug up online I'm under the impression that a failing cam sensor just makes it run crappy and sluggish.
If it is just that then I would assume it wouldn't be that sensor. But hey me and assumption never had a great mixture with other projects

 

A bad crankshaft position sensor (CPS) will have random failure of engine operation. When replacing, only select an OEM part, as others have reported issues w/ aftermarket parts.

 

Well after replacing parts and sensors and not getting anywhere, finally got it figured out. turns out the culprit was the coil plug wire. I noticed a spark, glad I didn't feel it, while she was running and I was tugging on wires and checking the plug wires. there was enough slake in the coil wire where it would make contact with the heat shield and it cut into it a little. After replacing and routing so it wouldn't touch anything else I was able to get over 200 miles with no issues. I hope this can help someone