Rear Wiper Not Working ?

[Dozer22]

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 ? thanks

 

[Me007gold]

Wiper motor? if you have access to a multimeter get it out and test the wires at the motor.

 

[jrSS]

 

[Dozer22]

anyone have a diagram of which fuuse is the rear wiper
?

 

[The_Roadie]

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.

View attachment 20041

 

[jrSS]

Here this might help....

bottom pic maybe not

 

[jrSS]

Check the bcm (fuse block under rear seat) and check fuse 9. That's rear wiper

 

[jccrall]

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]

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.

View attachment 20096

 

[jccrall]

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]

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]

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]

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]

Dozer22,

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

John

 

[Dozer22]

Check the bcm (fuse block under rear seat) and check fuse 9. That's rear wiper

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]

. 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]

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]

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.

 

[Bruter]

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.