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2002 gmc envoy_slt_xl
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Discussion Starter #1
I have an 02 Envoy XL. This past winter as it got very cold the rear wiper stopped working and at the same time the keyless entry stopped too. When it warmed up they bothed worked again when it got colder, they stopped. I also noticed when closing the rear hatch, the latch doesn't switch like it used to. The power locks work on the door switch but that does not lock or un-lock the back either. The dealer reprogramed the remotes but they still didnt work. It is now 80 degrees out and niether works anymore.
 

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2009 chevy
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I'll suggest two possibilities, 1. a bad ground on the liftgate or a ground supply point for the liftgate 2. a broken wire in the liftgate hinge bundle.

Sorry, just noticed it's ur 1st post. Welcome to the site.
 

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2002 gmc envoy_slt_xl
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Discussion Starter #3
Rear wires good all the way to the fuse box. Is there a seperate ground wire for the tailgate?
 

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2002 gmc envoy_slt
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Sounds like your liftgate module (LGM) may have gone bad.

In addition to the things you've described, does your rear defog work? When the liftgate is open, does the dome light come on? These functions are also controlled by the LGM.
 

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Rear wires good all the way to the fuse box. Is there a seperate ground wire for the tailgate?
Yes, there is a ground wire and a number of ground points, on and off, the gate. The wires may look and test good. Any time wires go from the body into a door or a hatch, there is a lot of movement and some times the back and forth movement breaks the wire inside the plastic. Sometimes the 2 pieces touch and the circuit works, other times they're apart. As u know, metal (copper wire) will shrink in cold weather, shrinking will open the circuit. Warms up, the wire expands and circuit works. Corroded grounds will perform this way as well.
 

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2002 gmc envoy_slt_xl
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Discussion Starter #6 (Edited)
I think it is the LGM there is power to it . No warning chimes when glass or door are open. Rear defogger not operating. Can it just be replaced? or is there programming involved?
 

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2002 gmc envoy_slt
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According to the service procedure, programming of the LGM is required to set the correct options for the vehicle, as well as reprogram the key fobs (the keyless entry receiver is integrated into the LGM).

Before you spend $$ on a new LGM, double check to make sure you've got battery and (as Rayvoy suggested) ground to the LGM. On the 4-way black connector into the LGM, you should have 12v at pins A & C, and ground at pin D.

Once you're convinced you need a new LGM - I'd recommend checking the LGM circuit board for bad (cracked) solder joints, which can be fixed with a soldering iron (you've got nothing to lose, right?). Thermal expansion and contraction can cause bad solder joints to fail intermittently.
 

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2002 gmc envoy_slt_xl
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Discussion Starter #8 (Edited)
How do you get the card out of the box?/ Figured it out. Power and ground all working, no cracks or corrosion at all.
 

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2002 gmc envoy_slt_xl
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Discussion Starter #9
I just figured out radio stays on with the LGM plugged in after keys are removed but not when not plugged in the radio does not stay on. Can part of it be bad. The dealership said $108 to diagnose, $200 for the part. and $108 to flash the new LGM. Does that sound right?
 

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I just figured out radio stays on with the LGM plugged in after keys are removed but not when not plugged in the radio does not stay on. Can part of it be bad?
Hard to say. All modules transmit a "state of health" signal periodically on the Class2 serial data bus, to let the other modules know they're operating correctly. If the BCM does not recieve this state of health signal from the LGM, it may disable the Retained Accessory Power function, as it can't tell whether the liftgate has been opened. In any case, it appears that the BCM 'knows' whether the LGM is present, which means that your LGM is communicating on the bus.

The dealership said $108 to diagnose, $200 for the part. and $108 to flash the new LGM. Does that sound right?
Sounds about right, for dealer pricing. The suggested list price for the service part is $149 - $199. You can buy the replacement part at GMPartsdirect for $77 + S&H (with keyless entry: PN 15869971).
 

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Discussion Starter #11
Part#?

I tried searching that part on the web sight listed and nothing was found. Is it correct, my module says 15092007.
 

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Strange. I get results when I do a search on gmpd for 15869971 - no problem.
You should be able to double check the PN by asking your dealer. Often service PNs are different than the ones used in prod'n.
 

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2002 chevy trailblazer_ls
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You mention the defogger doesn't work either. The defogger grid shares a single common ground wire with the LGM and the wiper motor back through the harness to the body. I would double check the ground back to the body. Use your DVM and check for voltage btwn the ground at the LGM plug and the body of the truck. Shouldn't be any significant voltage between the two grounds if there is you have an open ground. Might even try adding an external ground wire temporarily from the LGM plug ground to a good body ground point to verify.
 

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Discussion Starter #14
I got the new module but did not have time to get it programmed. Will anything work with out programming, will it hurt the new one if I plug it in and don't have it programmed?
 

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According to the service manual, programming is required to configure the LGM for the option content of the vehicle.

Truthfully, almost all of the functions supported by the LGM are standard equipment - rear defog, rear wiper, liftgate/liftglass locking and ajar indication - all standard. The only optional function I can think of is keyless entry, and the LGM hardware is differentiated for that (w/ or w/o integrated keyless receiver).

For my money, I'd plug in the new module and see if it works. I'm 98% sure you won't damage it - assuming that your original LGM just went belly-up on its own, and wasn't taken out by another problem on the vehicle, like a short in the wiring.
If it works, you should be able to reprogram the keyfobs yourself.
 

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2003 gmc envoy_sle
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I had similar issues

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.
 

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sort of the same problem

I am running in to the same problem with my 2003 trailblazer. Nothing that the LGM controls work but my license plate light are out as well. I pulled the boot off and saw i had one wire broken (small orange wire). I fixed that wire but still nothing. Does any one know where the ground points are for the LGM? I check the 2 right inside bed on both corners but they looked good. I am getting power to the lights but they still will not come on.

Thanks in advance for your help


:bonk:
 

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2005 chevy trailblazer_ls
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jebates - I have been struggling with the licence plate lights and thought I had a wiring problem. Turned out to be simply a broken bulb that sometimes worked and sometimed didn't work. Replacing the bulb solved my problem.
 
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