I have an 01 cherokee that has an intermittent spark problem. My friend has a snap on computer and we can watch the pcm loose a signal from the cam and crank sensor at the same time, resulting in no spark. Both sensors were changed twice. We checked 90% of the wiring and think it is an internal pcm error. Can I use another pcm out of the same year jeep with same options to test mine and see if the pcm is bad? Will it run and drive without re-flashing the donor pcm?

 

Welcome to the forum electro! I likely can't help you a bit. Usually it's not the Puter'. If you post up your codes, there are some pretty sharp guys here that may help though. I think in PA the parts store will read them for free. Be sure to wright down the actual code"s".

 

I can't answer your question but a quick tip.


If you want to know what's wrong with your xj and don't have access to your friends reader you. An use this site.

http://go.jeep-xj.info/HowtoECUcodes.htm

Helped me so much!

 

It would be unusual for the PCM itself to go intermittent like that, but the related plugs, grounds and wiring harnesses develop problems regularly. Give the wiring a good shake, see what happens. Also disconnect the PCM connectors and see what they look like.

I don't think you need a re-flash if the PCM is otherwise identical, but I haven't personally done it.