Author Topic: Replacement PCM in TJ?  (Read 862 times)

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moerl8088

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Replacement PCM in TJ?
« on: April 26, 2006, 04:13:30 PM »
Hi everybody,
my dad and I bought another wrecked TJ and this one had a front end hit that put the battery tray into the PCM.  So I just happened to get a 2001 PCM for a 4.0 manual on ebay for 60 bucks.  It's going in a 2002 sahara 4.0 5 speed.  I've been looking at alldatadiy.com and reading up on how to make it work with the key immobilizer system and whatnot, but I just thought I'd ask and see if anybody has done this before and if theres anything I need to watch out for.
Thanks,
Luke

Offline Jeffy

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Replacement PCM in TJ?
« Reply #1 on: April 26, 2006, 04:45:46 PM »
I'd leave out the Immobilizer if you can.
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moerl8088

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Replacement PCM in TJ?
« Reply #2 on: April 26, 2006, 05:53:51 PM »
I don't think its that simple.  A key code in the PCM needs to match whats in the ignition switch and whatever immobilizer computer is in there somewhere I think.  If I can figure out how to use our computer scanner thing to input the vin number into the pcm it'll work but have a permanent engine code saying that the key code doesn't match the pcm.  Otherwise I don't think I can just plug the computer in and expect it to work.  but who knows.  I was just hoping that maybe someone out there had replaced one before...
oh well.
Thanks,
Luke

Yellowcritter

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Replacement PCM in TJ?
« Reply #3 on: April 26, 2006, 09:29:18 PM »
Know we swapped out one, from a 98 to 00 or the other way around (can't remember) and didn't do anything except plug it in and it worked. Jeep has been on the road now for a few months and as far as I know he has had no probs. Should mention this was on a 4.0

moerl8088

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Replacement PCM in TJ?
« Reply #4 on: May 24, 2006, 05:44:19 PM »
Well I put in the computer and it runs, but the sentry key immobilizer system shuts it down after 3 seconds.  So based on what Alldada is telling me, I will either need to take it to the dealer when it gets the front axle underneath it to have them program the new PCM with their DRB III tool or buy a scanner that supports the "vin number write" function to manually enter the vin into the PCM.  I think I'm going to end up down at the dealership and having them do it because even our $600 autoxray scanner tool doesn't have the vin write function.
course, I could probably solve the whole thing by just cutting out the immobilizer unit attached to the ignition switch, but I'd rather not cobble job it.  and I'm worried that if I do something like that I'll have an amber immobilizer light or check engine light thats always on, and then it won't be able to pass inspection so the state of Wisconsin will liscense it.
not real important, but I thought I'd let everybody know what was going on and so that maybe some poor bastard with the same problem can find this thread on google and get a better clue about what to do.