2002 GMC Envoy Rear Liftgate Module [Archive] - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

: 2002 GMC Envoy Rear Liftgate Module


DaNile
04-24-2007, 05:43 PM
Dealer told me I need to have this replaced. Keyfobs inoperable, Rear windshield wiper as well. I told him I'd do it myself...I know you have to reprogram the remotes for keyless entry is there other reprogramming that needs to be done. And if so is there anywhere I can take it besides the dealer. Thanks Joe

PROSPHOTO
04-24-2007, 09:52 PM
You will need the Liftgate Module programmed once you put the new one in; but unfortunately I don't think anyone but the dealer can do it for you :yes:

Welcome to the site...please click edit profile under user CP & fill out some info for us :yes:

tblazed
04-24-2007, 10:33 PM
I would check the ground from the module plug back to the body first. Seems I recall a bad ground on someone's was causing similar problems ..no wiper and RKE receiver in the LGM not working.

DaNile
04-24-2007, 10:42 PM
Thanks for the replies ...i was afraid of that...having it replaced by the dealer is going to cost me over $400....Now I'm thinking of going and getting an aftermarket keyless entry system with remote start runing a special for $300 installed...the only thing that I notice not working besides the keyfob, and radio shutting off is the rear wiper....i can live without that. I guess the only tricky thing is the rear liftgate locking mechanism....I'll have to ask the installation pros about that one

PROSPHOTO
04-24-2007, 10:50 PM
Bypassing this module is not recommended :nono: This module is expected to communicate with the rest of the on-board computers and removing it from the serial line could cause indicator lights to remain on and possibly communication errors between other modules :duh:

RayVoy
04-24-2007, 11:12 PM
Before u spend all that money, stupid question: did u check the LGM fuses? There is at least 2 of them, fuse #3 & #6 in rear (underseat) fuse box. There might be more.

BTW, have u been following this thread http://forums.trailvoy.com/showthread.php?t=24508

DaNile
04-24-2007, 11:21 PM
I did check those fuses they are good.

prosphoto ...I didn't think about that...however right now it is not operational and everything is working fine on the car. The lock/unlock mechanisms work fine via the door switch..I do appreciate the concern before I do anything I will inquire with the aftermarket installer exactly what is going on before I proceed.

DaNile
04-24-2007, 11:28 PM
RayVoy Thanks for pointing out that thread..

I brought it to the dealer and he said LGM was bad ...not sure I trust him after reading this thread.
Let me tell you what doesn't work
1. Rear Wiper
2. Radio Shuts off immediately
3. Rear Tailgate locks do not work via door switch nor safety feature for glass and gate.
4. Rear defog seems to work ...when I hit the switch indicator light turns on...however I cannot verify if it is actually functioning because there is no fog on rear glass at this time.

Could this truly be the LGM or a bad common somewhere

RayVoy
04-25-2007, 08:17 PM
RayVoy Thanks for pointing out that thread..

4. Rear defog seems to work ...when I hit the switch indicator light turns on...however I cannot verify if it is actually functioning because there is no fog on rear glass at this time.

I don't know if this would work or not, find a cool shaded area, and mist the glass, Then turn on the defogger, u should see the glass dry along the heater lines.

One other thing to check the common ground theory, see if ur license plate lights work.

tblazed
04-25-2007, 08:26 PM
One other thing to check the common ground theory, see if ur license plate lights work.

Yep absolutely... that's another thing that fails if the liftgate ground is open :thumbsup:

DaNile
04-25-2007, 11:41 PM
license plate lights work perfect...

RayVoy
04-26-2007, 08:59 PM
license plate lights work perfect... That probably means the ground is good.

rg567
04-26-2007, 10:09 PM
I replaced mine myself and saved some money. The total bill was right around $200. Installation was simple, just pop off the trim on the inside of the liftgate and swap out the LGM. Only one catch: once you switch the modules the new one will look for a new code until you get it reprogrammed......meaning you'll have a dead battery in the morning...

Heres some more info:
http://forums.trailvoy.com/showthread.php?t=22112

chabs9
04-26-2007, 10:35 PM
just wondering if anyone else gets wind noise on the front windows of there 2005 envoy plain jane model??

DaNile
04-27-2007, 08:39 AM
Thanks for the info rg567...I was wondering if you could give me the part number for the LGM and where you purchased yours?

Thanks

Joe

DaNile
04-27-2007, 04:37 PM
Well I'm getting ready to pull the trigger on an LGM part no 15869971 is this the correct part number for a 2002 slt envoy 4x4.
I'm hoping I can just swap them out reprogram the fobs and be done...is this a fair assumption...

Thanks guys

Joe

rg567
04-27-2007, 07:35 PM
Thanks for the info rg567...I was wondering if you could give me the part number for the LGM and where you purchased yours?

Thanks

Joe

got it from the dealer, not sure of the part#...

kmat
04-28-2007, 06:43 PM
I just got same part from dealer. It needs dealer programming, only mine could not be programmed. Dealer needs to call GM tech assistance to figure out what was wring. Good luck!!

DaNile
06-09-2007, 12:28 AM
Okay here is the update hope everyone will find this helpful

Took Envoy to dealer they said I had a broken wire in the tailgate which they fixed...PROBLEM SOLVED! A few weeks later same symptoms...I took it back to dealer because they guarantee their work for so many months or miles...I was well within that range....They now tell me it is the liftgate module that is bad and would have to be replaced was going to come up around $400 which is when this thread started....I complained and told them they didn't fix it right the first time and I shouldn't have to pay...at any rate I told them not to fix it...I found a replacement module for around 100 bucks here locally...now I just needed someone to program it. This is where it gets interesting...I was lucky enough to befriend a GM mechanic took my Voy to his dealership swapped LGMs turns out after running diagnostics through his computer that the new LGM was not being seen by the computer. After further investigation found that the wire that was origially fixed at the other dealer split at the same spot...respliced and soldered and the old LGM still works PROBLEM SOLVED...sounds like to me they didn't want to admit they messed up their original wire repair blamed it on something else so that I can pay again. This really pisses me off....It was the orange wire that broke twice.
Moral of this story...check your wiring especially in the boot where the trunk opens and closes. He explained to me that extreme heat and I'm assuming cold along with opening and closing of the trunk wears the wires down. He also told me that the metal connectors inside the male and female plugs get spread apart and can cause intermittent failure as well. I have lost all faith in honest dealership repairs.

on a separate note

THE LGM MUST BE REPROGRAMMED BY THE DEALER IF IT IS TO BE REPLACED> IT IS NOT PLUG AND PLAY...

I didn't have to do that since my orignal one still works...I guess the bright side of the story is I have a brand new LGM in case the old one actually breaks...

leo_atl
11-13-2007, 07:09 AM
[QUOTE=rg567;334428]I replaced mine myself and saved some money. The total bill was right around $200. Installation was simple, just pop off the trim on the inside of the liftgate and swap out the LGM. Only one catch: once you switch the modules the new one will look for a new code until you get it reprogrammed......meaning you'll have a dead battery in the morning...

So what you're saying is that even if I buy and replace the LGM on my own, I'd still have to go to a dealer and pay for reprogramming it? Any idea how much would a dealer charge for it?

ReyRock
01-07-2008, 04:36 PM
Is the LGM located behind the little rubber boot that holds all the wires, slight left at the top of the lift gate? I have a problem with my license plate lights AND the rear gate not opening when using my remote. When I 'jiggle' or push/pull on the rubber boot, all the symptoms that I've been freaking out about for months, go away. :confused:

tblazed
01-07-2008, 11:31 PM
LGM is mounted down inside the liftgate. Where you are moving the rubber boot is where the wires break.



Is the LGM located behind the little rubber boot that holds all the wires, slight left at the top of the lift gate? I have a problem with my license plate lights AND the rear gate not opening when using my remote. When I 'jiggle' or push/pull on the rubber boot, all the symptoms that I've been freaking out about for months, go away. :confused:

ReyRock
01-08-2008, 02:13 PM
Thanks Tblazed! I can bet that some of those wires are shot. I'll have to take a closer look. Everytime I jiggle that boot, my cluster panel problems disappear and my liftgate operates fine, along with the license plate lights.

Cleo66
08-10-2008, 07:01 PM
I have had similar issues with my 2003 Envoy. We have had sporadic issues with the alarm, locks, keyless remote and liftgate and recently they stopped working altogether. We had tried resetting the electronics in the car by disconnecting the negative battery cable however the radio retained all of its settings indicating that there was a ground somewhere in the car. Last year we had the air conditioner serviced through warranty coverage because of a factory defect and since then we have not been able to use the lower front cigarette lighter ports. We took the dash assembly apart and noticed that the wires were no longer connected to the bottom ports. Today we found the wires deep inside the interior panel and connected them and now all of our problems have been corrected. The remote entry works and we no longer have a problem with the locks or the liftgage. I have read postings that have similar symptoms and I concluded that we may have a problem with our LGM however, my rear defogger, license plate lights and and rear windshield wiper continued to work. Reading these postings has helped me eliminate other issues while directing me to check for grounded wires. I hope this helps someone else. I'm so thankful I didn't have to spend hundreds of dollars to resolve this issue. Thanks to everyone who contributes here. I am an avid reader of TrailVoy and this is my first posting. I doubt it will be my last.

WOOLUF1952
08-10-2008, 11:26 PM
:tiphat WELCOME Cleo66 and don't forget to fill out your user cp.:tiphat

Chevy492
09-01-2008, 10:47 PM
So this is my first post on this forum but i have been reading it alot so i decided to post to see if anyone can end my headache...Anyway so my back lift gate doesn't work altogether i can say. THe windshield wiper doesn't turn on or the wash the lock doesn't work and in the winter i noticed the back defogger doesn't work nore the lincense plate lights. So i read this forum and concluded well possible bad Lift gate module but everyone says check the ground what wire is the ground? and i also noticed that when i have the door open the module makes a clicking noise.....i followed the wires up to the body and descover two wires were broke (a thick orange wire and a thick black wire) so i put the thick black back together and it seems to unlock the lift gate lock but will not operate with the switch up front for unlock and lock only when i touch the wire together it unlocks the door. Whoever had the vehicle before me had the keyless entry hooked up to the module and it might of messed things up...So i was wondering if this is a bad Module. Sorry for writing so much but i will be very happy if someone can help me get this tak'n care of before the winter hits thank you!!:)

RayVoy
09-02-2008, 08:47 PM
The BLACK wires are the grounds. There are many orange wires, so that one is hard to guess; but if it's thick, then it is designed for a lot of current.
When I tackle something like this, I look at the simple circuits first.

You said the lic lights don't work. Power/ground/2 wires/a socket and a bulb for each lamp.
They share power and grounds, if both are out (and the bulbs are good) check the common parts. You need to have, and be able to use, a multi-meter, but this is a simple circuit to trace.
And the bonus......usually when one problem is fixed, all problems get fixed.

And, hey man, welcome to the site.

Chevy492
11-06-2008, 06:33 PM
The BLACK wires are the grounds. There are many orange wires, so that one is hard to guess; but if it's thick, then it is designed for a lot of current.
When I tackle something like this, I look at the simple circuits first.

You said the lic lights don't work. Power/ground/2 wires/a socket and a bulb for each lamp.
They share power and grounds, if both are out (and the bulbs are good) check the common parts. You need to have, and be able to use, a multi-meter, but this is a simple circuit to trace.
And the bonus......usually when one problem is fixed, all problems get fixed.

And, hey man, welcome to the site.

hey sorry to reply so late its been i while since ive been on but it turns out my lic plate lights were only burnt out so i that good news that the lgm might still work?

phins2left
02-21-2010, 03:51 PM
Finally tired enough of not having rear wiper/defrost/Keyless entry that I've decided to try and chase my issue down.

Pulled the rubber liftgage boots...no breaks. I have 12v and 12v and ground at the actual Liftgate Control Module. I just put all the trim back together and checked the underseat fuses one more time and noticed something for the first time:

When I plugged fuse 6 back in, i heard a faint but distinct buzzing starting to come from the car speakers (there's one in the A pillar next to your head when you're checking fuses, otherwise I probably wouldn't have noticed). Now, the car was not on and the keys were nowhere near the ignition, so I'm wondering if I've got an even more advanced issue going on here? At what point does the audio system interface with the LCM/Security? The only 'point' that I can think of that uses or directs both systems would be the onstar (now defunct). Hmmm..... Any thoughts would be greatly appreciated!

the roadie
02-21-2010, 04:13 PM
... the car speakers (there's one in the A pillar next to your head when you're checking fuses, otherwise I probably wouldn't have noticed). ...That's not a speaker, assuming you're talking about the B pillar which is between the front and rear seats, although it does look like a grille. It's a tiny squirrel cage fan with a temp sensor that picks up the cabin air ambient temp for the digital automatic HVAC control system. It should only run when the ignition is on, although you might have reset the HVAC system and it's just running through the usual 90 second calibration process. It's one of trailvoys trivia contest answers - it stumps a lot of folks who ask what it is.

Yank the B pillar cover off and check. The A pillar is the slanted one closer to the windshield. Apologies if you already know this and I misinterpreted which grille you're listening to. :o

phins2left
02-21-2010, 05:28 PM
That's not a speaker, assuming you're talking about the B pillar which is between the front and rear seats, although it does look like a grille. It's a tiny squirrel cage fan with a temp sensor that picks up the cabin air ambient temp for the digital automatic HVAC control system. It should only run when the ignition is on, although you might have reset the HVAC system and it's just running through the usual 90 second calibration process. It's one of trailvoys trivia contest answers - it stumps a lot of folks who ask what it is.

Yank the B pillar cover off and check. The A pillar is the slanted one closer to the windshield. Apologies if you already know this and I misinterpreted which grille you're listening to. :o

But why then did it spin up when I plugged the #6 fuse back in? That fuse is labeled LCM. Hmmmmm......

the roadie
02-21-2010, 05:38 PM
Ahhh, 2002 is different from my 2004. I can't explain why the LGM fuse would reset the HVAC system. Anyway, if it spins down within 90 seconds, I wouldn't worry about it. If you have good power and grounds, then the LFM must be a lack of seria data communication to the rest of the vehicle. I think the LGM communcation wire goes to the rear splice pack under a carpet flap. I would see if the dealer can communicate to the LGM - might be a bad LGM or a bad wire other than power. Do you have a buddy to trade LGMs with?

De02Envoy
04-28-2010, 11:13 PM
Having same issues as everyone else in this thread. Where is the liftgate control module located? where is the ground wire located? I found that the big orange wire was broke. Spliced it back together, but only was able to get the rear defroster to work. Liftgate still won't lock, wiper/washer won't work and the key fob remotes don't lock/unlock. Yes batteries are good. This is driving me nuts! :crazy: Thanks in advance for any help!

pbagley
10-27-2010, 01:01 AM
Hi All, First post. Joined today after finding a thread on this forum on the liftgate control module problem. Glad I did because like so many my problem was not the liftgate control module, but instead the wires running from the body to the lift gate.

In my case it was the big black wire that was broken. The liftgate control module would click, click, click. The wiper was dead, the license plate lights also dead.

I had the door apart, and nearly replaced the liftgate control module last week. Lucky for me work was extremely busy, allowing me time to find this forum. Cost from the dealer was $180 for the part, and $120-150 for programming. Ouch. I fixed it tonight for nothing - I had some scrap black wire, a solder iron, and some black tape.

I unplugged the liftgate control module, spliced in the new piece of wire, soldered and taped. Then plugged in the module's 3 connectors. The lift gate locked. Tried the power locks from the drivers door - they lock but do not unlock. I unlocked the back door, and when I opened it the alarm went off. Cleared the alarm by starting the truck, then shut it off.

After this the locks work fine. I reassembled the liftgate door skin and was done.

Once again, a big thank you to those who have posted about the broken wires between the body and the liftgate. I saw a crack in the orange wire too, not yet broken. Has anyone bought a new wire harness from GM and installed it? How did it go?

- Paul

pdoc01
05-22-2011, 11:07 AM
I have been reading through threads and haven't seen my exact problem. I disconnected my battery to install a part, and when I reconnected it, the keyless entry, rear wiper, or liftgate locks didn't work. After reading the forum (you guys are great) I checked the fuses and the wires under the rubber. All checked out fine. I then checked to see that current was getting to the module, which it was. Could I have some how shorted out the LCM or erased the programming by disconnecting the battery? I tried disconnecting the battery again for a few hours to see if it would have any affect, but nothing changed. Any help would be appreciated because I want to exhaust all options before I have it checked by a dealer.

the roadie
05-22-2011, 11:42 AM
No way to damage the module by removing power. You probably have a communication wire problem, which may be in the roof headliner area as discovered by another member recently. Not inside the rubber boot, but somewhere where the wires MOVES when the liftgate opens. I'd look around more first.

pdoc01
05-22-2011, 11:57 AM
Thanks a lot ROADIE. I will have to check all of those wires. I only checked for visible damage at the boot and I checked the power and ground at the LCM itself. Time to put the meter on the rest of the wires. I'll report back.... Thanks again!

pdoc01
06-11-2011, 09:08 PM
I finally had a chance to re-check the wires. I found no problems with the connector or wires in the boot. Is there a way to check the blue communication wire? Or does anyone know what it is connected to so I can bypass it to test it? I saw a couple of LCM's on ebay for $25 bucks, even saw one for $9, but none of the part numbers match mine. Are there multiple part numbers that would work? One more question, if I bought a used LCM would it work right out the box or would it still need to be programmed by a dealer? Sorry this is so long, and thanks to anyone who can help.

CtDMonet
06-11-2011, 09:28 PM
I replaced my LCM when my door locks quit, several months ago. Everything mworked fine after that. Just a week or two ago, My remote Start (Viper) was acting up, so I switched back to the stock fob, and realized it didn't work. I assumed it was the battery (I hadn't used it in a couple years), and bought a couple new ones when I got a chance. It still doesn't work.

I followed the diag- on this (and another) thread, and noticed my lic plate light doesn't work.

Can I reprogram the LCM? I clicked on a couple (broken) links, and couldn't find the reprogram instructions...

RayVoy
06-11-2011, 09:47 PM
All of the electrics in the liftgate need a ground.
The license plate lights not working may indicate a missing ground.
The plate lights have the simplest electric circuit.
Does the driver's side tail light work (shares the plate lights fuse)?
No, check fuse #14 in the rear fuse panel.
Working tail light, check the plate bulbs.
Good bulbs? Check for 12 volts when the lights should be on.
No 12 volts? Try using a ground that is not on the liftgate and recheck for 12 volts.
If you now have 12 volts, you are missing a ground on the liftgate (check for a broken black wire in the wire bundle at the liftgate hinge.
Still no 12 volts, look for a broken brown wire in the bundle.

CtDMonet
06-12-2011, 12:48 PM
All of the electrics in the liftgate need a ground.
The license plate lights not working may indicate a missing ground.
The plate lights have the simplest electric circuit.
Does the driver's side tail light work (shares the plate lights fuse)?
No, check fuse #14 in the rear fuse panel.
Working tail light, check the plate bulbs.
Good bulbs? Check for 12 volts when the lights should be on.
No 12 volts? Try using a ground that is not on the liftgate and recheck for 12 volts.
If you now have 12 volts, you are missing a ground on the liftgate (check for a broken black wire in the wire bundle at the liftgate hinge.
Still no 12 volts, look for a broken brown wire in the bundle.

Found a link (http://forums.trailvoy.com/showthread.php?t=47196) and reprogrammed the remotes, and the fobs work fine now. It still puzzles me about the lic plate light. Everything else in the rear hatch works (wiper, locks, etc).

coastalplain
12-04-2011, 02:50 PM
Thank you all for the information provided to figure out the issue with fob failure, rear windshield wiper, etc. I have a 2003 Envoy, and both fobs stopped working the other day. The other folks on the thread indicated the broken wires, which was my problem. Several years ago, my rear wiper died, but being told I'd have to get a lift gate module, I chose to do without. The fobs were a larger problem, in that I had no access to the rear of the vehicle, and I couldn't open the tailgate to get to the wiring harness coming from the body to the tailgate. Good or bad, and desperate, I ran a ground wire from the battery terminal to the rear defrost connector, and the keys worked again, both verifying the broken ground and giving me access--I wouldn't do this bypass on my neighbors car--no telling the consequences of a possible short; Like I said, I was desperate and hoped fuses would go before anything else. Of the six wires, four were now broken, and the other two were on their way out.

If you go through the wiring fix yourself, some hints that helped me out:
1. After you do the bypass and get to the wires, disconnect the battery before making sparks fly;
2. Gently pull the rubber and plastic harness cover and protectors out exposing the six-wire plug and rear-washer fluid hose;
3. Disconnect the plug, remembering now that you will not be able to do the bypass if you close the tailgate again (you can use the round cover from inside the vehicle near the bottom of the back hatch);
4. I only had wires broken on one side of the plug, so I was able to label the positions (A through F) of each size and color wire;
5. Pop the two gray wire holders out of the plug to allow the wires and clips on the ends to come out; mine were tight, so I inserted a very small phillips head screwdriver (eyeglass size driver) to help it release. Notice the orientation of the wire clip within the harness and mark it in your notes.
6. Stripped, cleaned, wire wrapped, and soldered the broken areas, covered with electrical tape, and slid the wires back through the rubber protection.
7. When putting the wires back through, I used a small long screwdriver to push the wires through, and a bigger screwdriver to help pull the wiper fluid hose back through.
8. plugged them together, hooked the battery up, heard a click back there, and everything works now.