Carl48

You did quite a bit of troubleshooting on this problem without pinpointing anything definite. Sometimes a problem like this is the coil but you say there never is any voltage to the coil so that rules that out. You disconnected the 60 pin connector on the PCM and then re-connected it and you started-up. Could be a bad connection there or it may have allowed the PCM to "reset". Without a factory service manual in your possession, it would be very difficult for you to troubleshoot an apparently intermittent problem of this nature much farther. Sometimes the crank position sensor (CPS) goes bad, see if you set an 11 trouble code, that would pinpoint the CPS. In any case, you could try a new CPS but be aware that it may or may not solve the problem.

firstxj

I appreciate all your help! I just went to go do some more work on it today and discovered a new symptom. It may or may not help but you know more than I do so let me know if this sounds farmiliar. I have a high pitched whine coming from the computer when the key is on. I heard it from the other side of the jeep with the hood up. It is not extremly loud but loud enough that I could hear it from several feet away. I am thinking I might try going to the JY and grabbing a computer or $30.

'96XJSport

sounds like a bad crank sensor... it can be found inside the distributor and unfortunatly you ususally have to buy a new distributor

Carl48

The CAM position sensor is found inside the distributor, the CRANK position sensor is mounted on the transmission bellhousing.

Carl48

Your best troubleshooting tools are your 5 senses. Never have heard a whine coming from any Jeep computer...this may be the clue you need. You are sort of at that point where you may have to throw a part or two at this problem in desperation.

gil

HI, let me tell you that i had the same problem, my would stop running while i was on the road and start right up again. anyway the crank sensor was lose so i got new from auto zone for 70 buck and no more problem



96 cherokee

firstxj

Funny you say that, I just go back in from playing with it some more. I unplugged the CPS on top of the motor and left it unplugged for about 30 seconds and plugged it back in and it ran like a top. I drove it around for about 15 minutes and it ran perfectly. I am hoping this fixed it for good and if I continue to have issues then I will probably replace that first. I dont know what was going on with the computer but it was still making that noise while it was running. Is there a fan on that computer? Im curious if maybe it got some dirt or dust in it. My heep like most others has been in the mud a good bit so it possible that it may have gotten some in it if there is a fan? I dont know. Thank you guys so much for your help!

Carl48

Don't believe that there is any fan inside the computer...it relies on on intake air to cool it. There may be an oscillator inside running at a high frequency that you may be hearing (just a guess, unfortunately nobody seems to publish any details of what goes on inside the computer...maybe you just have great hearing...my ears may not be too good...too many years around aircraft). If the problem returns then throw a new CPS at it like you mentioned.

gil

Let me tell you that sensor IS A *****!!!! it will leave you stranded any were. I would replace realy quick. try to see if its lose, with your hand you can reach it .


96 CHEROKEE

fantic238

Next time i'll write it bigger since it was ignored two pages ago...

syncview

^hahahahaha

GM7203

I like this information. I'm having the same problem on my 92 that I just changed the motor in. All electrical was working when I pulled the old motor, so I suspect that I either broke a wire during the swap (where this info is going to be a real help), or need to clean up the stud on the side of the block where the dipstick holder is bolted and used as a ground. So thanks for the great input.

MissMomma87

Long shot with this being an older post, but I'm having the same issue with my 1993 Jeep Grand Cherokee. turn the key, lights come on & tries to turn over but then nothing. No power to t coil. Replaced the cam & crank sensors as well as the ignition switch. Checked gas, battery, started etc. now getting light codes 12 & 54!! 12 being the battery disconnected recently & 54 No camshaft signal detected during engine cranking.... But i just replaced the camshaft sensor so ????? Carl 48 are you still on here, you seemed to really know what you were talking about.

Donald Gideon

My 98 has new distributor cap rotor, cps , plug wires , ground from battery to frame, new fuel pump and coil...the coil gets power for about half a second when I crank it

joejohn74

Donald, I feel your pain. Here’s my issue:

when the PCM is supposed to provide ground to the coil, it doesn’t. When the key is in the run position, I have power. When it goes to the start position, the PCM drops ground killing power to the coil.

side note, this is a 95 4.0 that has All new components (except for the wiring harness and PCM). Engine is fresh from top to bottom. Relays have been replaced, fuses are all good. ASD relay clicks on, fuel pump relay kicks on, and best I can tell, all grounds are connected. I’ve check continuity on ALL circuits to the PCM.

I just dump ground to the coil when I turn the key to start. Also, coil heats up when I leave it in run, so I know I have power to the coil there.