Can i Swap a PCM ? Please help - Page 2 - JeepForum.com

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post #16 of 31 Old 08-22-2013, 05:38 PM
ZeeJay1997
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the vin imprinting/matching does not apply to ZJs. the 98s have vin numbers programmed in the PCM and BCM, but i have seen several occasions of mismatched vins on this year model with no problems.

the way i understand it, when the PCM was new from the factory and the switch was turned on for the first time, the BCM (or security system?) embedded the security configuration into the unit. it is either with security or without. from that point on, that's what it is. when you get a reman PCM, it should be set back to receive the security configuration

i have seen several cases where a non security PCMs from JY were installed on ZJs with security and they would not run more than a few seconds.

if i have drawn the wrong conclusions someone please say so because i'm working off what i learned on the forum.

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post #17 of 31 Old 08-22-2013, 05:48 PM
Gibby913
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That's exactly what's happening to mine.....so Im assuming Im suppose to have security (red led light on dash but never blinks nor has it ever).......does that mean this is a no-security PCM I have? Is there a way to tell what its configured for via the serial numbers or any other reference on the case?

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post #18 of 31 Old 08-22-2013, 06:08 PM
ZeeJay1997
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cant tell what it is from the label

the BCM controls the security light. the pcm just plays along
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post #19 of 31 Old 08-22-2013, 06:13 PM
Gibby913
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Does that mean I may have an issue with my BCM that's causing it to reject the new PCM but not the old?

-= 97 ZJ 4.0L I6 149k=-

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post #20 of 31 Old 08-22-2013, 06:17 PM
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.

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post #21 of 31 Old 08-22-2013, 06:27 PM
ZeeJay1997
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the red led doesnt work. does the security system work when locked with key fob? horn chirp?
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post #22 of 31 Old 08-22-2013, 06:39 PM
Gibby913
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Not really......I don't even think the parking lights flash.....just locks doors

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post #23 of 31 Old 08-23-2013, 09:00 AM
Jeeples
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Quote:
Originally Posted by ZeeJay1997 View Post

i have seen several cases where a non security PCMs from JY were installed on ZJs with security and they would not run more than a few seconds.

if i have drawn the wrong conclusions someone please say so because i'm working off what i learned on the forum.
That's incorrect, we took a non-security PCM out of the JY and put it in my buddy's '94 w/security and it runs just fine. The previous owner had replaced the PCM with one from a JY out of another ZJ with security and would only run for a few seconds.

The BCM only imprints code in the PCM if security is present. If there is no security present then the BCM doesn't imprint anything, meaning you can install a non-security PCM into a security equipped ZJ without issue. This is of course assuming the new PCM is good and the donor vehicle has a like drivetrain.

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Originally Posted by wjjeep19 View Post
It is what Jeeples has *PARTIALLY* stated.
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post #24 of 31 Old 08-23-2013, 01:24 PM
Gibby913
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hmmm.....here's my next question then.....If my security enabled system is NOT working (alarm won't arm or go off for whatever reason) but my Jeep will run with my old damaged PCM but not with the new security enabled PCM......What should I do???

-=Gibby=-
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post #25 of 31 Old 08-23-2013, 05:45 PM
ZeeJay1997
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how long have you owned this vehicle?

the only thing i can think of that makes sense (to my feeble brain) is that at some point, the secutity system was disabled or failed and someone installed a non security PCM.

something to ponder upon.
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post #26 of 31 Old 08-23-2013, 05:55 PM
ZeeJay1997
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Quote:
Originally Posted by Jeeples View Post
That's incorrect, we took a non-security PCM out of the JY and put it in my buddy's '94 w/security and it runs just fine. The previous owner had replaced the PCM with one from a JY out of another ZJ with security and would only run for a few seconds.
Do you think this could have changed on the 96-98? The security is part of the BCM. On the earlier models, the security is a separate unit
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post #27 of 31 Old 08-23-2013, 06:12 PM
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post #28 of 31 Old 08-23-2013, 06:43 PM
Gibby913
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Quote:
Originally Posted by ZeeJay1997 View Post
how long have you owned this vehicle?

the only thing i can think of that makes sense (to my feeble brain) is that at some point, the secutity system was disabled or failed and someone installed a non security PCM.

something to ponder upon.

That's the exact same conclusion Ive come to at this point.....I'm going to purchase a non-security enabled PCM and hope for the best......

I've heard that it will Marry itself to my security if its present anyhow if a non-security PCM is installed on a security enabled jeep.....is this true?

-=Gibby=-
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post #29 of 31 Old 08-23-2013, 08:28 PM
Jeeples
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Quote:
Originally Posted by ZeeJay1997 View Post

Do you think this could have changed on the 96-98? The security is part of the BCM. On the earlier models, the security is a separate unit
Doubtful as all the parts lookups I've seen for 96-98 PCMs make no specification for security or without security.

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Originally Posted by wjjeep19 View Post
It is what Jeeples has *PARTIALLY* stated.
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post #30 of 31 Old 08-24-2013, 02:34 PM
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I would have to assume that's correct because I've purchased more than one PCM for my 97 and not once was I asked about a security system.

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