Disturbed Posted March 11, 2014 Share Posted March 11, 2014 I think these two issues may be related but am not sure. My MJ decides at random not to start, always when it is a cold start and have never had it die while driving. Sometimes I can let it sit for a few minutes and it will fire right up, sometimes it takes longer until it will start, this weekend it just refused to start. I was getting no spark. Pulled the coil and ignition module, coil tested OK after I cleaned up the terminals but decided to replace it anyway since the terminals were corroded on both the coil and the ignition module. Threw the new coil in, nothing. Had AutoZone order me a new ignition control module for Sunday. Sunday I installed the new ignition module and it started right up, no issue and was running very smooth. For kicks I put the old ignition module back in, and it fired right up. I was still hopeful that it was a flakey module, had one on a YJ I had and a new module solved the problem. Put the new coil and module back in and called it a day. Monday morning started right up to go to work, and to go to lunch, and to go home, started a few times last night shuffling cars in and out of my garage doing maintenance on them and running to AutoZone to get an oil filter for my wife's car. No issues with the truck all night. This morning me and my boy hop in the truck to get him to daycare and it will not start. Same thing as before, cranks fines but no fire. Let it sit a minute or two, nothing. Couldn't wait any longer so we hopped in the ZJ and I took him to daycare. Ran back to the house after dropping him off to try it one more time before work, still nothing, just like it was doing on Saturday. I am not sure if it is a related problem but when I crank the engine over longer than normal, sometimes when I release the key the engine just keeps right on cranking. I believe that problem may be in the starter relay that is on the fender, I was going to replace that as well but AutoZone did not have a listing for that and I have not had an opportunity to look elsewhere. I am not sure if these issues are related and they very well may not be, the truck is 25+ years old after all, multiple unrelated issues at the same time would surprise me. If anyone has any ideas I would greatly appreciated. Link to comment Share on other sites More sharing options...
cruiser54 Posted March 11, 2014 Share Posted March 11, 2014 88? Click on the link in my signature and do posts 1 through 5. Link to comment Share on other sites More sharing options...
Disturbed Posted March 11, 2014 Author Share Posted March 11, 2014 88? Click on the link in my signature and do posts 1 through 5. Yes it is an 88, sorry I didn't mention that. I found your post and bookmarked it, I will try that tonight. Link to comment Share on other sites More sharing options...
cruiser54 Posted March 11, 2014 Share Posted March 11, 2014 88? Click on the link in my signature and do posts 1 through 5. Yes it is an 88, sorry I didn't mention that. I found your post and bookmarked it, I will try that tonight. SUPER important to do all 5 of them. Won't take but an hour and half maybe. Link to comment Share on other sites More sharing options...
Disturbed Posted March 13, 2014 Author Share Posted March 13, 2014 88? Click on the link in my signature and do posts 1 through 5. Yes it is an 88, sorry I didn't mention that. I found your post and bookmarked it, I will try that tonight. SUPER important to do all 5 of them. Won't take but an hour and half maybe. I printed your tips out and as soon as the weather cooperates I will be going through at least the first 5, all of them if I have the time. Thank you very much for your help. Link to comment Share on other sites More sharing options...
metrictonner Posted March 13, 2014 Share Posted March 13, 2014 Sounds like old opened up c201 c202 connector contacts, the ones that go into the ECU. I had this problem, thought it was the ECU itself. Ended up dissassembling the connectors and re-crimping those female contacts, something like 74 of them. You can test for this problem by removing the ECU from its mount and letting it hang by the connectors against the transmission tunnel. Diddling with the wires going into the connectors while trying to start or running will spot loose contacts. Fixed a lot of problems this way. Link to comment Share on other sites More sharing options...
Disturbed Posted March 17, 2014 Author Share Posted March 17, 2014 I ran through the first 5 steps and actually discovered 3 things. 1. The C101 connector had already been cleaned out, no black tar and it looks to be in good shape, someone had even added some sort of gel, like you see in the gel filled connector, to prevent corrosion. 2. The ground strap at the rear of the head was MISSING, nothing there, but there was one on the intake manifold so I picked up another ground strap at NAPA and added it to the rear of the head. 3. I definitely had an issue in the grounding in the wiring harnass, probing the TPS and checking to battery negative I would see the continuity come and go when shaking the wiring harnass. Pulled the wiring harnass apart and did the sensor ground upgrade, everything seems good now, time will tell but it has been fine since Saturday. Thank you very much for your help. Link to comment Share on other sites More sharing options...
cruiser54 Posted March 17, 2014 Share Posted March 17, 2014 Good to hear. Link to comment Share on other sites More sharing options...
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