TheWeasel

I had typed up this lengthy essay going over the ins and outs of the issues I'm having, but apparently I did something wrong and it didn't post or something.

To keep it comparatively short I cleared the adaptive memory on my PCM after performing an oil change, cleaning my IAC valve with throttle body cleaner, and applying dielelctric grease to all my sensors as it has been raining heavily in my area for the past few weeks. The jeep ran fairly well prior to this (I say fairly well because it has nearly 300k on the odometer) and these repairs were only meant to be a bit of preventative maintenance.

The jeep ran and drove like a champ for about half an hour, until it would start intermittently shut off completely, then jolt back to life while driving down the highway (at least once every minute or so lasting anywhere between one and three seconds). I stopped at a friend's and found that wiggling the ASD relay caused a crank no start issue, so I took apart the fuse box and made sure all the connections for the ASD were snug. Cranked the jeep up, and made it about another half hour down the road before the issue repeated itself, but this time after fooling with the relay wires, the jeep cranked and almost immediately died, and the relay started clicking continuously until I turned the key to the off position.

After multiple attempts to fix the issue I've found that unplugging the crank sensor has no effect on the clicking, but unplugging the cam sensor causes it to stop. Also if I reset the PCM the relay acts normally until I try to crank it again, which causes the continuous clicking to start again. I've tried everything I could think of to troubleshoot the issue with the limited amount of tools I had at hand.

Something else of note is that after letting it sit for about an hour with battery cables, PCM, and both the crank and cam sensor unplugged for about an hour, I tried cranking it again, and this time it idled for about 15-20 minutes before shutting off and this time the ASD relay didn't start clicking until I turned the key off and back on. Heat related?

In the short bursts that I am able to keep the jeep running I don't notice anything strange on the gauge cluster (no fluctuations in voltage, tach, or oil pressure gauges), and it doesn't run rough, hot, or rich before it shuts off completely.

I had it towed to a nearby friends house which is where it currently sits, but I need to get it running soon because it is my daily and only means of transportation.

Any tips or insight from much more mechanically/electrically inclined individuals would be much appreciated. I have Haynes manual to reference from as well as a spare crank sensor and ignition coil that I'm going to try tomorrow, and I'm going to buy another cam sensor.

Feel free to ask any questions because I know I didn't provide all the required information, but as I mentioned before this is the short version of the post I attempted to make earlier.

awg

I assume you have swapped the ASD relay with one of the others in the PDC ?

If you have, and the problem persists, I would do the following things.

remove the PDC and make a minute examination of each of the pins and wires leading to it...it does sound like you have an intermittent poor connection, conduct continuity tests for each wire wherever it goes to

closely examine the wiring to the cam sensor, is a known issue

study the section of the manual that covers the ASD operation. it is very detailed

any OBD codes ?

TheWeasel

I'm new to actually posting on this forum, so I'm not sure if I'm replying to this properly. I tried swapping the ASD and starter relays, but this had no effect on the clicking. Still tried to crank, so the relay appears to still be operational. All the wiring in the fuse box appeared to be alright (it was drizzling outside, so I didn't spend too much time digging into the wiring). I was at a friend's house when I was doing most of the work trying to fix it, and didn't have access to a multimeter or code reader, but in the most recent visit to the autoparts store I had a code P1698 which I believe had something to do with signals to and from the PCM.

awg

Possible Causes

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.

• Faulty Transmission Control Module (TCM)
• Transmission Control Module harness is open or shorted
• Transmission Control Module circuit poor electrical connection
• Faulty Powertrain Control Module (PCM)
• Low battery voltage

sounds nasty, the ASD relay will not work correctly if any fault is detected by the PCM

Sounds like a wiring/connector issue to me, as it is intermittent

imo, you absolutely must download and study the relevant section of the FSM, can be done free from this site, use the archives, Cruisers page still has them

in the meanwhile, unplug the TCM, and see what happens (gear changes must be managed with the stick)

TheWeasel

I'm heading to work on the jeep rn, I'll be sure to thoroughly pick through the wiring for the ASD relay itself, as well as the cam and crank sensors. I'll see if I can get a video of what it's doing to better display the issue. I'm going to stop by a parts store to pick up a cam sensor. I would order a quality one, but I'm on a time crunch, and if I can atleast verify the issue with a crappy sensor I'll be satisfied. I'm also going to see about checking a junkyard for a PCM to try. I doubt I'll be able to get the PCM because it's a Sunday.

TheWeasel

I am fairly confident in saying that the PCM is the issue. When I disconnect the TCM and plug it in just enough for the pins to touch the connectors the ASD starts the clicking again. Also when I disconnect the TCM and reconnect it the CEL briefly goes away, then returns. When I went to the parts store the P1698 was the only code that appeared. I'm guessing the TCM got fried somehow when I went to flash the adaptive memory.

97grand4.0

Is the voltage to low to hold it i ?

awg

Maybe the bolded PCM is a typo?...do you mean TCM ?

imo, its stilI more likely than not its to do with wiring, so I would examine the harness and connector pins with bright light and magnification

TCM are very cheap to buy used (I got a used one for $20)

I have an entire spare '96 same as mine, I bought it v cheap, got it running and keep it running, the reason is so I can sub in a known good part if needed, saved me a few times

Jeepfreco

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TheWeasel

Well ladies and gents... I think I found the actual issue. Diagnosis is that I am a dumbass. I was waiting till my paycheck hit yesterday before buying a new computer, but in the meantime I was scouring all of my wires and whatnot, and while looking at the ignition coil I found a ground wire that wasn't properly connected. Directly underneath the coil there was a stud with three ground wires running to it, and two of the three were properly mounted to the stud, but one was just off to the side. It was still touching the stud, which I guess gave it enough of a ground to work sometimes, but not enough to keep it grounded while driving, causing my intermittent, and unpredictable issues.

TheWeasel

I'm guessing that whenever I replaced the old ignition coil I had mistakenly disconnected the grounds underneath, or perhaps they had gotten in my way when I was trying to remove the coil, and I had just missed one of the grounds while putting it all back together.

awg

those 2 x earth studs are critical as most of the vehicles critical electronics rely on them

well done finding the issue

Roler

For future reference