So the history of this is my buddy's 1999 XJ was having issues with starting up, running for only a few seconds then shutting off. We went through every sensor we could think of, tested all electricals and had it scanned with an ODBII scanner. No codes. After re-cabling the battery, thinking it might be a ground issue, the truck ran a bit better but would experience the issue once it had run for more than 10 minutes and was then attempted to be restarted.
This would lead to the situation again where the XJ would start, then shut off after about 3 seconds. It turned out the ECU or PCM or whatever its supposed to be called was extremely hot after a shutdown. Cooling it off would allow the vehicle to be restarted without issue. So the plan was to replace the computer with a matched unit from another XJ. The original was an 56041-493AD so we found a 56041-493AE, understanding this was essentially the same computer with a newer firmware we felt confident it would just swap in. The donor was a 99 XJ with matching specs (4.0, auto etc) but following the swap the XJ wouldn't run for more than 3 seconds with the new PCM.
So the end result is we had to put back in the other PCM, which would allow it to at least run. Is there any other reset process, or re-programming needed to address using a new PCM? Any ideas or paths we should pursue? We're replaced the TPS, CPS and MAP sensor and everything else we could think might be causing this issue. Thanks for any input or ideas,
Tim 'Skorpyo' Kilpatrick
This would lead to the situation again where the XJ would start, then shut off after about 3 seconds. It turned out the ECU or PCM or whatever its supposed to be called was extremely hot after a shutdown. Cooling it off would allow the vehicle to be restarted without issue. So the plan was to replace the computer with a matched unit from another XJ. The original was an 56041-493AD so we found a 56041-493AE, understanding this was essentially the same computer with a newer firmware we felt confident it would just swap in. The donor was a 99 XJ with matching specs (4.0, auto etc) but following the swap the XJ wouldn't run for more than 3 seconds with the new PCM.
So the end result is we had to put back in the other PCM, which would allow it to at least run. Is there any other reset process, or re-programming needed to address using a new PCM? Any ideas or paths we should pursue? We're replaced the TPS, CPS and MAP sensor and everything else we could think might be causing this issue. Thanks for any input or ideas,
Tim 'Skorpyo' Kilpatrick