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2003 gmc envoy_sle
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241 Posts
Discussion Starter #1
Ok recently my rear wiper has been acting up. I rarely use it but just last week it starting going crazy. In the off position the wiper sits below the window. Without turning it on sometimes the wiper will go up to the window and then sit back down as if I were turning it on and off quickly. Is there a fuse or something I can pull to fix the problem?
 

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2003 chevy trailblazer_lt_ext
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771 Posts
First thing I would try is to disconnect the battery for .5 hr, seems like a software glitch to me. Others may have better suggestions.
 

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If it is a blown fuse, it wouldn't work at all. Maybe a short in the motor itself. My TB's rear wiper acted screwy a few times but has been great for the last 35k or so.
 

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2003 gmc envoy_sle
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Discussion Starter #5
I tried pulling different fuses but couldnt find the one for the rear wiper. Finally i just took out the entire switch. I think this stopped it for now
 

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Looks like it's embedded in the LGM (Lift Gate Module).

Here's what I found:

===============

Rear Wiper/Washer System

REAR WIPER/WASHER SYSTEM COMPONENTS
The rear wiper/washer system consists of the following components:


Rear wiper motor
Rear washer pump
Rear wash relay
Rear wiper/washer switch
LGM 30 A fuse
WASH 20 A fuse
REAR WIPER/WASHER SYSTEM CONTROLS


Body control module
Liftgate control module
Rear wiper/washer switch
REAR WIPER/WASHER SYSTEM OPERATION
The rear window wiper/washer switch is an input to the body control module. The requested rear wiper mode is sent to the liftgate control module by the body control module as a message on the serial data circuit, and the rear window wiper motor is controlled by the liftgate control module. The switch power circuit to the rear wiper/washer switch is a 12-volt reference supplied by the body control module. The rear wiper/washer switch is a series of resistors and the switch position is determined by the voltage of the rear wiper/washer switch signal circuit to the body control module. The rear wiper/washer switch has continuity at all times and the body control module expects a rear wiper/washer switch signal voltage in all switch positions including OFF. The rear wiper motor is supplied battery positive voltage and ground. The liftgate control module controls rear wiper motor operation through the rear wiper motor control circuit. The rear wiper motor control circuit is supplied a battery positive reference voltage by the rear wiper motor module and is pulse width modulated to ground by the liftgate control module. The duty cycle of the pulse width modulation determines the rear wiper motor operating mode. The lift glass and lift gate ajar switches are inputs to the liftgate control module and rear wiper motor operation will be disabled whenever an ajar condition exists. The rear window washer pump is controlled by the body control module through the rear washer relay. Battery positive voltage is supplied to the coil and switch sides of the rear washer relay. When the rear window wash request is active the body control module energizes the relay by grounding the relay coil through the rear washer relay control circuit. When the relay is energized battery positive voltage to the relay switch is supplied to the washer pump control circuit.

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Try pulling the LGM/DSM fuse (fuse nbr 6) in the rear seat fuse box just for the heck of it. It's not a fuse I would pull just to disable the rear wiper permanently however.
 

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2003 gmc envoy_sle
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Discussion Starter #7
When I go to lunch im going to see if pulling the switch stopped it from happening. I'm assuming without the switch the motor wont work. Only problem now is telling whether its my switch or the actual motor. Any ideas???
 

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2002 chevy trailblazer_ltz
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53 Posts
I am having the same problem any updates on this anyone??? mine makes a weird sound like its getting some poer but not enough to move the wiper. Then the wiper will go on as if i turned it on but i didnt. Its very annoying since it makes a loud sound kinda like errrrrrrrrrrerrerrr errrr. even if i turn it on it will go on like it is suppose to then go all the way down like i turn it off and come back up and wipe the window again.
 

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2005 gmc envoy_sle
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Same thing just recently happened to my 05 Envoy, bringing it in this weekend for some warranty work.......
 

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What the problem actually is.

Just realized how old this thread was, however maybe it can still help someone. Just for some background, I'm a GM tech with about 10 years of electrical, diagnostic background. This is a common problem. Easy diagnosis, turn the rear wiper switch on. It either won't move, or will jump erratically. Go to the wiper arm and help it along with your hand. Odds are it will move a bit, then stop. You have to replace the rear wiper motor. Basically, the wiper motors inards (gears) are stripped. Hope this helps.
 

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2006 chevy trailblazer_lt
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I've had my wiper in the OFF position and it suddenly turns on too. It started once I put my system in.


Coincidence?

Probably. It's only happened twice. And it works fine when I turn it ON, so I don't care.
 

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2007 gmc envoy_slt
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Rear Wiper

Pirate,

I have had my system in my 07 Envoy since I bought it (June 2012) and I have never had an issue with it. However, my rear wiper did randomly die, I just noticed this morning. I went and got a new fuse and switched that out but still did not work. I had an extra few minutes so I went into the hatch and looked at the wires running through the rubber, sure enough the orange power was split right in half. I just tied the two ends together to test it and I shut the hatch and boom power it works again! I am not saying that your system did not do something, but since I had the same issue I figured I would let ya know my stats. Now, I just have to properly reconnect the wires when I get home tonight! :D
 

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What the problem actually is.

Just realized how old this thread was, however maybe it can still help someone. Just for some background, I'm a GM tech with about 10 years of electrical, diagnostic background. This is a common problem. Easy diagnosis, turn the rear wiper switch on. It either won't move, or will jump erratically. Go to the wiper arm and help it along with your hand. Odds are it will move a bit, then stop. You have to replace the rear wiper motor. Basically, the wiper motors inards (gears) are stripped. Hope this helps.
That is not the problem park switch is the problem
 
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