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rear wiper doesn't work

84K views 79 replies 39 participants last post by  juniblazer77 
#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.
 
#4 ·
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.
 
#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
 
#6 ·
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.
 
#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?
 
#8 ·
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.
 
#9 ·
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:
 
#11 ·
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.
 
#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:
 
#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.:)
 
#19 ·
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?
 
#21 ·
I have an 04 Trailblazer, and I've had a similar problem: up until two weeks ago, my rear windshield wiper worked 100% of the time. Now, the wiper arm works like it's supposed to be, but the washer fluid doesn't come out when it's supposed to. And when I lifted my tailgate to investigate, there was wiper fluid all on the jamb (where the gate locks into the car) like it had all leaked on there. I'm gonna try and take the plastic stuff off (the interior vinyl stuff) to see what's up next weekend.

Suggestions?
 
#23 ·
I have the same issue in that the rear wiper does not work. Didn't try the washer. My hatch electric lock doesn't work either. Both started at the same time and in fact the remote will not function despite a new battery.
The receiver for the remote unlock is the rear liftgate control module, which also controls the other functions you have problems with. It could be that its fuse (#3 in the rear fuse block) has gone, or a wire in the harness going to the rear liftgate module is bad. They often break over time due to flexing near the hinge where the liftgate opens. Check out the wiring hidden by the rubber boot.

If your rear washer pump works, that's entirely controlled by other circuits, and not the rear liftgate module.
 
#24 ·
My rear wiper works, the license plate light works and I think the rear defrost works (too warm to really tell) Fuses 3 and 6 under the rear seat are good and the radio stays on until I open the door. My problem is the liftgate or glass will not lock with/without the remote. All other doors lock but on the lifgate I can open with the lever or the glass can open by pushing on the button. Is this the wire harness issue or the liftgate module shot ?

Thanks.
 
#29 ·
Took the panel off and checked all 3 orange wires got 12.7 v. Check continuity on the wires and they were good. So I climbed in and start locking/unlocking with the remote and noticed the switch on top (where the lead is) is try to move a lever of some sort but I couldn't see. I pulled the complete unit off and the arm the switch was trying to move was rusted tight (where arrow is).
Everything is back to normal now, thank you Roadie for the tips.


http://s184.photobucket.com/albums/x157/Menthol_03/?action=view&current=SeizedLatch.jpg
 
#30 ·
Sorry to bring a thread back from the dead, but I am also suffering from rear wiper failure and cannot seem to find the source. I just bought a 2002 LTZ, and the PO said that the rear wiper hadn't worked for awhile.

I have checked fuses #3 & #19 in the rear fuse panel, and they both appear to be good.

I did not see any frayed or broken wires in the loom running through the top of the hatch.

I did find that the hose for the rear washer appeared to have popped loose right near the wiper motor, which may explain why some of the metal clips holding the trim on were rusty. I put that back together and it seems to be spraying properly now.

I noticed a fair amount of corrosion on the wiper shaft, which I cleaned up, but that made no difference.

The motor itself looked to be in OK shape, and I have 12V on the orange wire in the wiper motor harness, but the green wire (pin E I think) is always at ground. Vehicle on/off, wiper control on/off makes no difference here.

Since my keyless entry works and I think my defroster does as well (it gets 12V when the defrost setting is on) I don't think the problem is with the LGM.

Any thoughts?
 
#31 ·
Rear circuit breaker #9 brings 12V to the rear wiper motor, (for future reference) but you don't have that problem if your orange wire has 12V. Check A (black) to be a good ground. The dark green wire is a PWM signal from the LGM, so if you command high speed wiper action, that wire should read 5-10V on a meter set to the DC scale, and perhaps the same on a meter set to AC volts.

If the control wire isn't getting any PWM square waves, then perhaps the speed control switch up front isn't getting read by the BCM. Pull the switch from the dash, and check the white wire (pin A) for a 12V reference signal, and the output gray (Pin E) will have a voltage that varies according to the position of the switch. The switch is full of discrete resistors like a potentiometer with a jumpy output.
 
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