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2002 gmc envoy_slt
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Discussion Starter · #1 · (Edited)
Recently purchased and had a 2002 Envoy SLT rebuilt (it was in an accident). This turned into a chore when the frame damage was more than what was expected. We did a frame swap, new steering column and front end parts. Engine and tranny were ok.

After the column swap I found instructions here about how to "reprogram the security settings" (thanks). Everything is finished and working great except front door pw/pl heated seat buttons etc. are non functioning as well as the liftgate wiper and washer. We haven't had a chance to program keyfobs but suspect they would not work right now anyway (for front doors). The front drivers window worked once before the start of the rebuild. No problem with back doors.

After reading dozens of posts here the body shop and I checked the wires in the liftgate (everyone one of them) for continuity and power. We checked out the LGM as best we could for power in and out. All fuses under the hood and under rear seat are fine. We also checked the wires in the front door hinges. All check out ok.

We swapped a drivers door module with another vehicle and my module operated the windows and locks in the other vehicle. The other module was non-functioning in my Envoy.

We checked power to the rear fuse box, the door switches and every other wire, fuse and relay (swapped several relays) all checked out ok.

A tech II scan showed no communication with the door modules.

The radio shuts off when the doors are opened (no reserve power) and the dome lights do not come on when the front doors are opened. After starting engine we hear a series of clicks from the back like doors attempting to lock.

Drivers mirror control works but won't control pass. mirror. License plate light works but wiper and washer on lift gate do not.

It appears from everything I have read here and the testing we have done that this may be a bad body control module.

Any suggestions for other things to check?

I have tracked down several used bcm's (I believe this would allow me to avoid reprogramming). If it is the BCM is there anything else I should watch for?

Thanks for any help or guidance here.
 

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2004 gmc
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Sounds like not just data comm problems to the door modules but also to the LGM. You might need to troubleshoot the data comm issues by pulling one or the other of the splice packs in case of a module or harness problem that isn't a BCM failure. (Discussed in other threads)

But I'd try the BCM first. If only you had a local buddy to swap with.
 

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2002 gmc envoy_slt
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Discussion Starter · #3 ·
Not familiar with splice packs

Thanks for the reply.

I am not familiar with the splice packs..are you thinking the non communication with the door modules and lgm may mean a problem in one of the wiring harnesses or a different module?
 

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Discussion Starter · #4 ·
I may have a buddy to swap with

My son owns either an 08 or 09 TB (not sure which). Would the BCM work either way or only if it is an 02-08 model?
 

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Discussion Starter · #5 ·
BCM Swap question

Do the vehicle options have to match to test a BCM by swapping it? Is there a specific ID number that has to match? Is the potential for damaging the swapped BCM fairly low?

My sons TB is an 06 so it may work although he does not have heated seats.

Thanks for any help with this.
 

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You'll have to do the security relearn procedure when you do the swap. I learned that fact when I did a BCM swap with a buddy that had an Envoy.
 

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Discussion Starter · #7 ·
Do the options on the vehicles or ID have to match

Thanks, I'll remember to do that. (Another half an hour I will never get back).

Do the options on the vehicles or ID of the BCM's have to match?

Both to test or replace the BCM?
 

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Discussion Starter · #9 ·
new information...maybe

I was lucky enough to get a free scan from the local gm dealer!!! I am still in shock myself.

The scan showed a serial data comm. code from the BCM and the instrument cluster. Why the instrument cluster is coding I don't know. Except he said that was possible since they are in the same circuit. He could not communication with the drivers door or lift gate modules at all.

He said they would need to poke around and see if there is a bad ground, broken wire or if one of the modules was bad! I think I am right back where I started from. Any hints or clues from this? Thanks again.
 

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2004 gmc envoy_slt_xuv
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I replied on your other post and now I see why you asked about grounds.

As stated by others, it appears you have a Serial Data problem.
All intelligent modules connect to this Serial Data bus. And all can be seen by a top end scan tool like the Tech II at the GM Dealer.

If the tool cannot communicate with a module other modules will set codes based on the lack of required communications from certain modules. (your Cluster set a code) All modules need power, ground and communication to all of the other modules.

There are (2) splice packs for the Serial Data bus and all modules connect either to another module or directly to one of the splice packs including the OBD connector.

One splice pack is located below the Headlight switch around where your left knee in while sitting. It is supposed to be attached to the left side lower sound panel on the left end. The other splice pack is neatly tucked under the carpet under the second row seating and accessed easily by a carpet flap already cut in the carpet. These splice packs are used to isolate and diagnose communication issues.

Hope this helps, I understand you are only checking places where the body shop has worked on to suspect problems. May have to spread out your search for wiring damage (grinding/welding areas?? door sill repairs??)
 

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Discussion Starter · #11 ·
thanks for the splice pack locations

Thank you bromanjr, I appreciate the info about the location of the splice packs.

I will post back what i find.
 

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Discussion Starter · #12 ·
Update

First I want to thank everyone that replied to my original post. I appreciate the help. A special thanks goes to bromanjr for the location of the splice packs. ( I sound like I just won a grammy or something)

After locating the splice packs I showed them to the person at the body shop that had done all of the work. He noticed a frayed wire by the rear splice pack and pulled the carpet back even further to expose a nest, that's right Mickey and his friends had evidently moved in during the rebuild and made them selves at home. The body man removed the rear seats and pulled the carpet back to find another nest back toward the liftgate and four wires that were chewed through. One light blue, orange, purple and I am not sure of the other wire. After a thorough cleaning we believe the mice are gone but i am going to set a couple traps in there overnight for a week or so.

After the wires were repaired everything works fine. Door locks, windows, rear wiper, the works. It just goes to show you that communication is everything. Who woulda guessed this one???

I guess checking for droppings ought to be added to the list of "first things to check".

Thanks again, I really appreciate all of the help. :weird:
 

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2005 gmc envoy_sle_xl
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Recently purchased and had a 2002 Envoy SLT rebuilt (it was in an accident). This turned into a chore ...

...the body shop and I checked the wires....
Are you paying the bodyshop with insurance money or paying them yourself? If it's covered by insurance you have the option to complete the rest of the repairs at a different body shop if the first one can't hack it. I would suggest a GM body shop. They should have all the neccessary documents and parts/scanners/tools/know-how.
 
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