1995 Cherokee 4.0 manual. not starting, had a diagnostic at the local dealer and they told me it was the pcm. they wanted $600, and more than $200 to install it. I picked one up at a wrecking yard and want to know if i can check to make sure it is functional or what is required to sync it with my jeep?

 

just undo the 5/16 bolt holding the harness to your original pcm, then just unplug the harness and plug it into the replacement computer and see if the jeep will start. if it seems fine, then unbolt the original computer and bolt in the new one. don't forget the bolt to hold the harness in place.

you can swap out the computer in about 10 minutes. junkyards have them for under 100 bux.

don't forget to unhook the battery before you attempt to undo your computer tho. and don't hook it back up for about 10 minutes after you plug in the new pcm.

 

Ok i have done that. it is still not starting so it was either not the pcm, or the one i got from the junkyard is also faulty?

 

not likley the pcm, poor diagnosis. Have you had the cps checked? the basics, spark, fuel?

 

i replaced the CPS before i had the diagnostic, have intermittent spark at the coil, no spark from the distributor also new; wires, plugs, cap, rotor, CMP

 

Where is the pcm located on a 96, i cant find it or dont know what im looking for i guess. any help appreciated thanks

 

drivers side inner fender. has a big wiring harness attached to it with a bolt in the center of it.

looks like this

 

I am having trouble finding a pcm for my 1994 jeep grand cherokee limited 4.0 4x4 automatic. Any ideas

 

tones of them in the junkyards. around here anyways.

as for the location of the pcm, it's kinda tucked away and hidden on the passenger side inner fender/firewall under the hood.

 

what if any are signs you may need a new one? I can't figure my studdering, sensor changing codes, badly running XJ out.

 

how can u tell its ur PCM?

 

Lets go back to the original post....

Did you test or replace your ignition coil? Freshen ALL engine grounds? The ASD (autoshutdown) system still in play too.

More on the ASD below.

Spark: 12 volts from ignition switch to the ASD relay; when the key is first turned on the PCM provides a ground to the ASD relay to energize it, then the ASD relay passes 12 volts to the coil primary side. If no crank sensor signal is generated after a couple of seconds the PCM cuts the ground to the ASD relay (and fuel pump relay too) and that cuts power to the coil (and fuel pump). Key to START and once again the PCM energizes the ASD relay. Now, a critical element is the crank sensor--no signal from the crank sensor and the PCM won't trigger the coil to provide spark.

 

on the same subject. what if the PCM needing to be replaced is the wrong match for the Cherokee? I am thinking that may be the case for mine. I'm either the 3rd or 4th owner of my '95 Sport.

 

Bump. Anyone?

 

maybe call a ecm place might help theres lot of one for your year maybe vin will helphttp://www.autocomputersystems.com/index.php