PCM Replacement
 

Hey guys,

It finally seems that replacing the computer on my '96 4.0 Manual Trans could be the fix it needs. I've looked into upgrading the computer and found out that they do not make them anymore, and have read that buying a rebuilt PCM from the dealer is the best way to go.

Before I do this, however, I have a mind to pull one off a junker first and try that. My mechanic says I can just pull one off and plug it right in to my Jeep without any reprogramming. Is it that easy? Any input is appreciated.

Will

Yep it's that easy. Match year and driveline. car-part.com is basically a search engine for salvage yards, and they have several listings.

If it was a 97+ you'd also have to worry about the possibility of the sentry system, but I don't think that was an issue with the 96.

You can always check the for sale section on this site, you may find just what you need and not have to scrounge through a salvage yard in hopes of finding one. I'd check the engines/tranny/t-case section, maybe try a search for PCM or computer also.

Update: Got a PCM from a junkyard and installed it, however my woes continue as the Jeep still powers down sometimes when it warms up.

Question: Today I flashed the PCM by touching my battery cables together for about a minute, and I know it takes about 50 warm up cycles for the computer to learn the correct settings. Has anyone ever noticed funky behavior during those initial cycles (like increased throttle on its own, the engine dying softly or sputtering out?)

I'm hoping the answer is that this is normal behavior, but I'm guessing it's a safe bet that the new PCM did not fix the underlying issue and its the same problem I've been having.

Note from DJ
Jeep still powers down sometimes when it warms up.
That’s a very vague statement. Try explaining your problems with your Jeep in a little more detail with the hope that some on else has had the same problems and solved it.

Thanks, will do in the future. I'm not seeking help for that particular problem here, just curious if anyone has flashed their PCM and noticed any strange behavior after doing so.