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2008 gmc envoy_slt
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Discussion Starter #1
My 2003 Envoy rear wiper does not work. It started to work once in a while, now not at all. I put another used one in it from a junk yard and it still does not wok. Could it be the rear body control module? The washer fluid still works. How can I test the pig tails that lead to the module to see if I'm getting power from the wiper switch. Also from the module to the wiper motor. That way I can try to narrow down the problem to the switch or the module.
 

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2006 gmc envoy_sle
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1,614 Posts
could be the tailgate contol module
 

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2008 gmc envoy_slt
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Discussion Starter #3
That's what I was afraid of. I'll have to try a salvage yard first. Dealer wants $150. But, you think it's more the rear control module than the switch? Thanks for the help Keith
Bryan
 

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2004 gmc
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26,181 Posts
The wiper could also be dead from flexed wires in the hatch harness.

Check the motor connector. Pin C (orange) should be 12V all the time, not switched with the ignition. Pin A (black) will be ground. Pin E (D-GN) should be at ground when the liftgate module tells the motor to run. The liftgate control module gets its instructions from the Body Control Module over the serial data link. The BCM gets its instructions by an analog signal from the rear wiper control switch pin E (GY). The switch inserts a variable amount of resistance in the circuit from Pin A (WT) which should be at 12V, fed from the BCM.

It's impossible to predict what the failure is without your going in there with a meter and reading some voltages to see where the desired signal goes missing. Do you have a meter and know how to use it?

There are also fuses and a motor circuit breaker in the possible list of things that can cause the problem. What we don't have is a traditional old-fashioned design where the power goes to the switch, and then straight to the motor. Everything seems to communicate via the data bus.
 

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2008 gmc envoy_slt
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Discussion Starter #5
I have a meter from an electrician at work, I've never used it myself. I think I can use it if I know where to set the meter to. I tried to use it on the continuity setting but now I know that was the wrong setting. I will try to go out and use it again on the voltage setting. Do I use it on the AC or DC setting? I also had an electrician test the circuit breaker under the rear seat, it tested fine. Your post was very helpful so far.
Thanks very much
Bryan
 

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2004 gmc
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26,181 Posts
Use it on DC Volts. If there is a input wire that's black or labeled GND on the meter, hold it to the vehicle's metal frame or a screwhead fastened to the frame. Scratch through paint if you need to. The RED or IN lead wire is where the signal you're measuring goes. Sorry I was out of the house for a while.
 

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2008 gmc envoy_slt
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Discussion Starter #7
I have nothing out of the pig tail that goes to wiper motor. Now I have three pig tails that mount to the lift gate module. I have one white pig tail and two black pig tails. The white one mounts to the driver side of module, the black one that mounts to the passanger side of the module has one smaller orange wire and one bigger module. The only wire that has any volts out of it is the small orange wire out of the black pig tail on the passanger side, it reads 8 volts.

I don't know where the BCM is located so I could not test it or the wires coming off of the switch. Where are they located?
 

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2004 gmc
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The BCM is just forward of the fuse panel under the rear seat. It uses a flex connectors and it's not as easy to troubleshoot.

If you have no 12V on the orange wire at the motor, that's the first (and perhaps only) thing to fix. Nothing about the motor can work without 12V. Since it's not switched on or off with the ignition, it should be there all the time. It comes from Circuit breaker 9 in the rear fuse panel. Measure the voltage in the socket after taking the breaker out. One of them will be 12V. Then measure the orange wire again at the motor. If it has no voltage, the breaker is bad or the wire is broken, probably where it flexes near the hatch hinge. Ask your electrician buddy for advice how to check the wire for continuity. If the wire breaks from flexing, the break can be hidden inside the insulation and you can tell by the way it bends differently at the break.
 

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2002 chevy trailblazer_ls
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88 Posts
rear body control module (BCM)

My 2003 Envoy rear wiper does not work. It started to work once in a while, now not at all. I put another used one in it from a junk yard and it still does not wok. Could it be the rear body control module? The washer fluid still works. How can I test the pig tails that lead to the module to see if I'm getting power from the wiper switch. Also from the module to the wiper motor. That way I can try to narrow down the problem to the switch or the module.
I have the same problem... Replaced my rear windshield wiper motor yesterday with another one and it still doesn't work... and every once in awhile I will have where the back won't unlock...

When you have the rear completely open do you hear a clicking sound every 2-3 seconds? I traced it back to the BCM... At the dealer they run around $125-150... I just bought a brand new one today off eBay for $50, I hope this will solve the problem. Probably take a week for it to come in...

Will keep you posted...

Here is what the one on my TB looks like... Sorry didn't take a wider shot... i just took the picture for myself for the Part# (apparently GM changed the part#... Mine (2002 TB) is showing P/N#15092007... when searching, it corrected me with the "new" P/N#15135616)

Old one:


New one from eBay:
 

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2008 gmc envoy_slt
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10 Posts
Discussion Starter #10
That is the exact same part no. as the one I have. I replaced it with one from the junk yard and I still have nothing. The wiper fluid would work with the old one but not the new one. Please keep me informed. thanks
 

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2003 chevy trailblazer_ltz
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i just made a post about wiper working a bit, then going out. found the problem in the rear tailgate where the wires are covered and run from the tailgate to the roofline. The wires were broken and frayed from years of tailgate use. I would pull that conduit out and check the condition of the wires in that area. You might find that to be the problem like mine.
 

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2008 gmc envoy_slt
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Discussion Starter #12
Best I can tell nothing out of socket. I couldn't tell if the probe made it all the way to the contacts. I have to find a small piece of metal that will fit in there to be able to check it. So far it doesn't look good:ugh:
 

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2008 gmc envoy_slt
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Discussion Starter #13
I decided to give up after I ruined where the circuit breaker goes. I can't lock my truck with the key fob anymore and my lift gate won't unlock. I really messed it up, so before I do more damage I'm throwing in the towel. I will write more later after I find out the problem on Monday. Thanks to everyone for your help.:eek::duh:
 

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2003 chevy trailblazer_ls
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I'm really anxious to see where this post goes, because i'm about to start at the conduit looking for breaks. I hope thats as far as i have to go. Oh, I get the clicking sound too, and have had to get jump starts from it draining the battery overnight a few times.
 

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2008 gmc envoy_slt
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Discussion Starter #15
After I tried to check the current through the #9 circuit breaker in the fuse block under the rear seat. The contacts in the fuse block could not make contact with the circuit breaker it's self. When that happened I could not open the rear hatch, I couldn't lock the doors with the key fob, and the radio turned off when I turned the key off. The only way to fix the breaker problem was to replace the block itself. The dealer wanted $425 to replace it with a new one. I found one at the junk yard for $60 and the dealer installed it for about $100. After all that it was just a broken wire in the hatch. I would try that for sure before you get to involved with anything else. Good luck.:)
 

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2003 chevy trailblazer_ls_ext
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i have the exact same wiper problem in my 03 trailblazer ext. Exactly where are the wires that become frayed/broken.
 

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2002 chevy trailblazer_lt
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heres another rear wiper that quit. my tb is a 2002 and i have none of the problems mentioned EXCEPT the wiper arm starts to move onc or twice then nothing....no clicks or noises.
 

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2002 chevy trailblazer_lt
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My situation is that on my 02 Trailblazer, the other morning with frozen weather I tried turning on the rear wiper. After a click it just stopped working.
Now, whenever I turn it on, I hear the motor working but the wiper does not move at all.
What's a noob like me to do? Do I need to replace the entire setup for one of those 07 setups I saw on another thread? Is there any way I can reconnect the arm to the motor? Any other ideas?
 

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2002 chevy trailblazer_lt
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My situation is that on my 02 Trailblazer, the other morning with frozen weather I tried turning on the rear wiper. After a click it just stopped working.
Now, whenever I turn it on, I hear the motor working but the wiper does not move at all.
What's a noob like me to do? Do I need to replace the entire setup for one of those 07 setups I saw on another thread? Is there any way I can reconnect the arm to the motor? Any other ideas?
yeah thats the way mine happened too. we had a nice ice storm a couple months back.:(
 
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