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Greg A
Greg A, Master Troubleshooter
Category: Chevy
Satisfied Customers: 7947
Experience:  Working with Electronics & Cars for 25+ Years
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2003 LS: rear wiper..trailblazer..the fuse, and fine

Customer Question

My rear wiper on my 2003 LS trailblazer does not work. I Have replaced the fuse, and module and still no luck. Front wipers work fine. Can you help me. Thanks
Submitted: 7 years ago.
Category: Chevy
Expert:  Greg A replied 7 years ago.

Hello & Welcome,


Do you have a test light or multimeter you can use to do some testing?


Also, what fuse and module was replaced?



Customer: replied 7 years ago.
Do not have either but can get them in AM. Replaced rear wiper module that is located on the back of lift gate.and rear wiper fuse in fuse box
Expert:  Greg A replied 7 years ago.

Was that fuse actually a circuit breaker? That is what I am showing on my schematic.



Customer: replied 7 years ago.

Is that what you call the fuse that is a lot bigger looking than a normal fuse

Expert:  Greg A replied 7 years ago.

It would probably look a bit like these circuit breakers (left side of picture), except it would have a 15 stamped on it.




It should have also been in the Rear Fuse Block - under the seat if my memory is working.


Let me ask you a silly question: Does the washer pump for the rear window work?

Customer: replied 7 years ago.
Yes it looked like ones on left. Yes the washer works.
Expert:  Greg A replied 7 years ago.

OK - Let me grab the schematic and send it to you. Then you can do some testing when you get the tools tomorrow.


Back soon, Greg A.

Customer: replied 7 years ago.
Thank you. I will let you know if it works and will reply back to you
Expert:  Greg A replied 7 years ago.

Here is the schematic, with all the major parts highlighted.




I would start at the rear wiper module and test that power and ground are making it to that module. The pins to check are shown in the schematic (Pins C & A). If those are good, then I would put a meter probe on pin E (the control pin) and see what it does when you turn on the rear wipers. If it is NOT changing, then you know you have a problem in the control system.


From that point, you would have to jump back to the body control module (BCM) or the rear wiper switch and see if the input pin to the BCM is changing when the switch is run through the different positions. There won't be a lot of change, but you should see the voltage change as you move the control.


If all that is working, then you would need to use a class 2 scan tool to see if the BCM can "talk to" lift gate module. But these tools are very expensive, so unless you have a friend that works at a GM dealership, then you may be stuck.


Please let me know what you find with the tests that you can do in the morning.