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Replacing the PCM
12-06-2009, 07:23 AM
#1
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Model: Cherokee
Replacing the PCM
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?
12-06-2009, 07:53 AM
#2
CF Veteran
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.
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.
12-06-2009, 09:28 PM
#7
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drivers side inner fender. has a big wiring harness attached to it with a bolt in the center of it.
looks like this
looks like this
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08-26-2010, 09:46 PM
#9
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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.
as for the location of the pcm, it's kinda tucked away and hidden on the passenger side inner fender/firewall under the hood.
03-05-2011, 04:44 PM
#12
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Location: In the middle of Minnesota!
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Year: 1999
Model: Cherokee
Engine: 4.0
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.
Last edited by tjwalker; 03-05-2011 at 04:46 PM.
04-25-2011, 08:05 PM
#13
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Year: 1995
Model: Cherokee
Engine: 4.0L High Output
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.
05-03-2011, 10:59 AM
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Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
maybe call a ecm place might help theres lot of one for your year maybe vin will helphttp://www.autocomputersystems.com/index.php
Last edited by freegdr; 05-03-2011 at 11:01 AM.