Rear Wiper Not Working ?

Dozer22

Original poster
Member
Dec 17, 2011
29
ive searched the forums a little bit and cant seem to find an answer . I have an 04 TB my rear wiper isnt working when i turn the knob to 1 2 or 3 it doesnt make a sound nd doesnt move , however when i press the spray button in the middle it sprays but still no movement any ideas on the problem:confused: ? thanks
 

jrSS

Member
Dec 4, 2011
3,950
ad6de943-8422-d0e7.jpg
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
The washer motor is up front at the reservoir, so its function is separate from the wiper motor, even though the switch is combined. An important test is if your rear defogger wires work, especially if you don't have the remote unlock function. But the most common cause of a dead rear wiper is broken/flexed wires inside the rubber boot at the liftgate hinge line. Over time, the conductor can break or get intermittent, even if the insulation is intact. Bending them can usually tell if the inside conductor is broken. Then you need to splice around the break. Metering the motor can also tell if the motor itself is the problem, but I think that's only about 10% of the time that happens.

Here's the schematic.

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jrSS

Member
Dec 4, 2011
3,950
Check the bcm (fuse block under rear seat) and check fuse 9. That's rear wiper
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jccrall

Member
Apr 3, 2012
11
OK, I have exactly the same problem with the rear wiper (dead??). Fuse #9 is not blown and looking at the wires in the lift gate hinge boot does not show any that are broken. I guess the next move is to expose the wiper motor and put a meter on it.

Anyone have hints as to how to get down to the motor level?? Are there any test points in the wiring harness that will allow me to meter the control circuit with out exposing the motor???

Thanks in advance.

John
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
The motor and the LGM (liftgate control module) are both in the liftgate and all you do is pull the inside trim panel.

I don't have a better schematic at the moment, but here's one I posted before in a galaxy far far away.

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jccrall

Member
Apr 3, 2012
11
Thanks Roadie,

I was able to download the "official" 2007 wiring diagram from this site and I will have to decipher it

Am I correct that the motor will only run if it receives a proper signal on the speed control wire (line E which is dark green)??? It looks like the orange wire (C) should have 12 volts standing at all times and the black wire (A) is a ground wire. I assume the speed control signal is digital -- is that correct???

Anyway, I will not have a chance to look at it until next week with all the Easter stuff coming down.

Thanks again,

John
 

DocBrown

Member
Dec 8, 2011
501
I'm betting the motor is shot, more likely than a wiring issue. I went through this as well as seeing lots of posts on the OS about this same issue. Spent a lot of time tracking it down only to bite the bullet and pop $140 on a new motor which fixed the problem.
 

jccrall

Member
Apr 3, 2012
11
Thanks Chuck,

Testing the motor is the next thing on my list but Roadie in an earlier post says that the motor is shot in only about 10% of the dead rear wiper problems. In any case, if it is the motor gone south, I will probably hit the junk (oops I mean salvage) yard first for a replacement.

John
 

Dozer22

Original poster
Member
Dec 17, 2011
29
Yes the rear defrost is still working. Havent had time to check the fuse yet . Is the fuse located under my rear seat or under the hood?
 

jccrall

Member
Apr 3, 2012
11
Dozer22,

The fuse (which is called a circuit breaker on the wiring diagram) is under the rear seat. It is #9.

John
 

Dozer22

Original poster
Member
Dec 17, 2011
29
silvernclean said:
Check the bcm (fuse block under rear seat) and check fuse 9. That's rear wiper
ad6de943-87e4-ec1c.jpg

ok how can i tell if the fuse is not working correctly my fuse thats in the 9 spot is a silver box about an inch tall and non transparent
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Dozer22 said:
. a silver box about an inch tall and non transparent
That's an auto-resetting circuit breaker. You can only test it fully with a voltmeter. Swapping with an equivalent neighboring component might help, but if the wiring or socket is the culprit, won't help as much. Pretty much every electrical problem needs a meter and a bit of experience to troubleshoot. Do you have a buddy with both those things assuming you don't?
 

Bruter

Member
May 13, 2016
14
Timmins, ON
Old thread...but does anyone know how to bench test the motor? If I could bench test it, I could rewire it to work. I bought a new motor but still does not work.
 

Mooseman

Moderator
Dec 4, 2011
25,344
Ottawa, ON
Download the manuals (link in my signature) and check the wiring schematics. Before you bastardize the wiring, check the wires in the boot between the hatch and body. Well known wire failure point. Pull and tug on each wire as they usually break internally and it isn't visible.
 
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Bruter

Member
May 13, 2016
14
Timmins, ON
Thanks. I do have the schematics from the GM manual. Just need to know how to bench test the motor. Seems simple but I tested the motor in another Envoy and it works fine but can't get it to work outside of a vehicle.
 

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