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2004 gmc envoy_sle_xl
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Discussion Starter #1
I recently installed an AUX GM aux input adapter in our 2004 Envoy XL. Every thing worked fine for about a week then the lock remotes stopped working. I changed the batteries in the remotes and tried reprogramming the remotes and still they did not work. Then I noticed that the rear window wiper was not working and when I hit the auto door locks the rear gate did not lock as well. I checked all fuses and did not find any bad. I do not know how to check the relays. I have since removed the AUX GM and nothing changed so I guess that was not the problem. I pulled the rear gate apart and noted that some of the wires have power.

Does anyone have any ideas. Where can you buy relays or is that likely not the problem.

Thanks,
Bruce
 

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2002 chevy trailblazer_ls
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2,216 Posts
Could be one of the wires that passes through the rubber boot at the top of the liftgate. They get bent with every opening and closing. Do the license plate lights work? If a broken (open) ground wire, the lights will be dead too. You should find Orange (x2) 12V Battery voltage, black GND, Light Blue Class 2 serial data, and Brown Left side marker power for the license plate lights.
 

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2004 gmc envoy_sle_xl
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Discussion Starter #4
License Plate Light

Yes the license plate light works. I just can't find a relationship between remotes and rear gate wiper/lock. Also the cabin light do not operate when the door open. They will turn on manually but not with the doors.

Thanks for the help so far!!
 

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2006 chevy trailblazer_lt
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3,497 Posts
The lock operation and keyless entry operation are through the Lift gate module, so is the control for the rear wiper...that's the relationship that ties the two problems together :yes:

You may only need the module re-flashed, but you may need the module replaced (which would also require programming)

Programming must be done by the dealer...that may be your best solution at this point :undecided
 

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2002 chevy trailblazer_ls
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Yes the license plate light works. I just can't find a relationship between remotes and rear gate wiper/lock. Also the cabin light do not operate when the door open. They will turn on manually but not with the doors.

Thanks for the help so far!!
As Prosphoto said the liftgate module does several functions. It contains the RF receiver for the key fobs. It communicates with the body control module via the Class 2 serial data bus on the lt blue wire. You could have a broken lt blue wire. Without that module communicating you will get symptoms like you describe. Sometimes the module itself fails but I would sure look at the condition of those wires where they go through the rubber boot first to make sure they are intact, because replacing that module and having the dealer program it can run several hundred $$.
 

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2004 gmc envoy_sle_xl
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8 Posts
Discussion Starter #7
I'll Check the wires

Thanks for all the advice. I will check the wires this weekend.
 

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2002 chevy trailblazer_ltz
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7 Posts
Issue Resolved?

BMC, were you able to resolve this problem??

My '02 TB LTZ is having the same issues (minus the key-fob)
 

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2002 chevy trailblazer_lt
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Same problem

I have the same problem with my 2002 TB and also my dome lights wont go off without pressing the override. First of all, I was wondering if the dome lights are related to the rear body control module or not and how to fix that maybe. And second, what problems would it cause If I were not to replace my module. I understand the keyless entry, rear wipers and defroster won't work, but do you know if anything else would malfunction and possible cause death of some sort? Just wondering.
 

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2006 gmc envoy_slt_xl
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Same deal!

When I started reading this thread, it sounded like I could have written it! Same exact problems: keyless entry does not work and rear wiper does not work on my 06' Envoy SLT.

This is VERY frustrating because it is an intermittent problem, and of course never happens when I'm at the dealer. The Envoy is still under warrantee, but seeing as "nothing is wrong" when I bring it to the dealer, they don't fix anything! :mad:

I'm going to check the wires as described elsewhere in the thread- I"m hoping one is just loose or partially damaged so I can do a quick fix.

FWIW: When the keyless entry does not work, it is impossible to open up either the rear hatch or rear window! Talk about frustrating!! :confused:
 

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2006 gmc envoy_slt_xl
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Damn!

Well of course neither the rear wiper nor the keyless entry are currently working. And of course that means I have no way to open the rear hatch.

Anyone have any way of manually popping the rear hatch and/or door?

:hopeless:suicide::suicide:
 

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Stop the Clicking!

The lock operation and keyless entry operation are through the Lift gate module, so is the control for the rear wiper...that's the relationship that ties the two problems together :yes:

You may only need the module re-flashed, but you may need the module replaced (which would also require programming)

Programming must be done by the dealer...that may be your best solution at this point :undecided
I am having similar problems. I can also add that when you open the rear lift gate you hear a constant clicking. I fear that the module is blown but would it click? I read in previous responses above and one mentioned getting it rebooted? Is this a dealer only option or are there any "home remedies" I could try?
:confused:
 

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2004 gmc
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Anyone have any way of manually popping the rear hatch and/or door?
There's a procedure in the Owner's Manual involving a little hole cover in the door inside panel.
...are there any "home remedies" I could try?
Pull fuses #3 and #19 from the rear fuse block for a couple of minutes, then reinstall them. That should reboot the module. You might have intermittent power or data communication connections to the liftgate module because the wires flex in the harness near the hinges. If you have electrical repair experience, you might look there. Many reports of very odd symptoms come from flexing wires that are in the process of breaking apart inside the wire insulation.
 

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2002 olds bravada
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key fob, rear wipers, rear defrost, rear liftgate lock/unlock

I am having many of the same issues.
1) Key fob not functioning
2) rear liftgate not locking/unlocking from button or keyfob
3) Rear defrost and wipers not working

However my rear lights are all operable (license plate and brake lights/reverse lights)

All my wiring looks ok in the rubber boot area. Is there a good way to check for an open circuit on the wires if they fail internal? I am not sure exactly where they land on the fused side.
Is there a way to test the LCM to confirm that is the problem? Any test for the communication (Blue wire) to confirm it has continuity.
Weird thing is that everything in the back, with the exception of the 12V accessory plugs, were working last week. All fuses look good that I can tell. ANy ideas?
 

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2002 olds bravada
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The lock operation and keyless entry operation are through the Lift gate module, so is the control for the rear wiper...that's the relationship that ties the two problems together :yes:

You may only need the module re-flashed, but you may need the module replaced (which would also require programming)

Programming must be done by the dealer...that may be your best solution at this point :undecided
How would I "re-flash" the module?
 

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2002 chevy trailblazer_ltz
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2002 TB liftgate problems (electrical)

All this sounds so much like what I am battling with on my 02 TB. My RKE just stopped working. All the interior lights are on constantly , unless I defeat them using the button on the headlight switch. The liftgate and lift glass do not lock .
The rear wiper motor is inop. The only thing that is working back there is the license plate lights illuminate (big whoop!!!) It just happened all at once. I have gone over the wiring , to some detail in that area, more to do-haven't found any problems there. I am really thinking that the LGM (liftgate control module) is in need of reprogramming or replacement. Just trying to do my very best to keep from going to the dealer at all costs but I am thinking that I am getting close to giving them a visit.
 

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2002 olds bravada
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Problem fixed

Thanks everyone for your detail about this problem. I found out that I did in fact have a few wires in the rubber boot that frayed and broke apart. Just opened the boot in the rear and tugged on the purple communication wire and sure enough it was disconnected. I just repaired the wire and everything works again. Thanks:thx
 

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2002 chevy trailblazer_ltz
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Yes, same results for me. Thanks to everyone for the information that kept me steered in the right direction. Of great help was the mention regarding the orange wires going into the LGM both needing to have 12volts. I dug deeper into the problem (wiring harness) and found that one of the orange wires did not have 12 volts at the input to the LGM.. I did more detailed looking at the wiring in the boot between the body and liftgate. I found 2 butt splices in the small orange wire. One of the splice connections was loose/broken. I actually soldered in a length of wire to get rid of the multiple splices. Now everything is back working , like it should. I know for a fact that all the information that was provided here, enabled me to find this and fix it. Much appreciated.
 

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2004 chevy trailblazer_ls
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similar issues with my 04 TB...

hey all!
i just acquired a TB about 6 months ago. she has a laundry list of what I would call "minor" issues. haven't fixed them due to time/money constraints.
security system is wacked. my keyless entry doesn't work even after buying New remotest and having a dealer attempt to program. however, the truck randomly locks herself now and then after i exit and shut the door. (doesn't want me driving her anymore?)
and better still, sometimes when unlocking the door, security system goes off and horn starts hooking until i start the truck.
rear defrost and wipe don't work.
liftgate and glass do not lock.

after speaking to a buddy who used to work at firestone and now at carmax, he suggested either broken wiring, a faulty LGM, or some issue with grounding wires.

sidenote: service 4wd light is on, check engine light just came on, and a dealer could not read any codes cause their code scanner thingy couldn't communicate with my truck.(I believe due to whatever issue is going on in the liftgate.)
due to the lack of a garage, the presence of snow in upstate NY, and my hatred for cold weather I don't like the idea of checking fuses. either way, i know they're all somewhat simple but apparently wallet-shriveling fixes. if anyone has any feedback on any of these issues, I'm eagerly awaiting. love my TB and would love to have her 100% functional. and then I can look into upgrades. :D
thanks guys... oh, my uncle is a certified GM Mechanic, so i have a possible benefit there. he just hasn't had time to bring anything home and get ahold of me to troubleshoot. and again, money is an issue. it'd be cheaper than going to the dealer he works at, but he needs some money too, understandably.
 

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2002 chevy trailblazer_ltz
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Had the same issue

I found that the ground wire was broken. Piss poor design. I spliced the ground wire and moved it out of the way and have not had a problem since it is commom to the wiper motor and the rear door lock

Hope this helps

Scott
 
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