1996 Cherokee. Power everything, cruise control, 4WD auto AW4 4.0
I've been chasing a no start issue in my free time over the past few months. No fuel pump priming, no OBDII connection even though it has 12V. I've gone through every wire, fuse, relay, connector... everything that could've been a problem has been fixed or replaced. I have had no luck finding a PCM that will work with my jeep ( from my limited research it seems a 1996 will only work with 1996 ) and today I've managed to find a working 1999 PCM and TCM. 99 PCM plugs right up but TCM is completely different ( go figure ), so it won't plug in. From what I've seen, the 99 TCM won't work even if I can manage getting it wired up due to the updates from 97 on. I Plugged the 99 PCM in with the 96 TCM and lo and behold she fired right up! It runs rough for sure but I've solved my problem. Sort of... The 99 PCM doesn't like the 96 TCM and when I tried putting it in reverse, it stayed in reverse. Won't even go back in park. Will I be able to go to a dealership or someplace and get the 99 PCM reprogramed or am I stuck going with a FS1 rebuilt or new 96 PCM. I've had no luck finding a used one and I don't want to spend $650 - $1,200 if I don't have to.

 

Not shifting past reverse or back into park is a mechanical issue, not an electronic one. The 99 trans computer will not shift correctly with the 96 trans. I'd keep the 96 trans computer and just ignore any *****ing from the engine computer.

 

There are some used ones on eBay and a few vendors advertising $200 repair services.

 

Stick with a '96 PCM mixing years is a headache. The '99 PCM won’t play nice with your '96 TCM, and reprogramming likely won’t fix it. Try FS1 or scour junkyards for a '96 PCM. Yeah, it’s pricey, but it’s the only sure fix. Sucks, but that’s the XJ life.

 

I agree the best approach is a genuine used 96 PCM from a wrecker, or advertsie on "wanted" here

A 96 is needed cause earlier are OBD1 and later ones are linked to the TCM and will throw a CEL at the very least

If you Google, Ebay or check archives, I am pretty sure there is some place in USA that sells repaired ones, no core needed, others need a core, they had a warranty

They often fail due to a bad capacitor, output transistor, or cracked internal connection, I think they may have been about US$400