2007 trailblazer rear wiper

[upnorth]

Rear Wiper quit working. Anyone have any idea what fuse control that thing? I have poked through the fuse panels, both under the hood and under the rear seat and can't find anything definitive. I can't believe how many fuses that thing has in it

[Jeremy airjer W]

It's a circuit breaker located in the rear fuse block. Should be labeled RR WIPER. The switch sends a signal to the BCM which them sends a signal to the LGM which tells the rear wiper what to do.

The rear wiper should have three wires. One will have power, one will have ground, and one will be the control wire.

[upnorth]

Cool...thanks will have to check it out. Messed with a little before, but was looking for a fuse and vaguely remember something labeled like that.

[upnorth]

Ugh...changed the Circuit Breaker and still no go. I assume I am looking at either the switch or the wiper motor. Anyone have tips how to rule one or the other out?

[Jeremy airjer W]

You could spend about $3,500 to buy a scan tool that will help narrow it down, spend $100 +/- to find out, or you could replace both and still have the same problem.

The third wire is the signal wire that tells the wiper what to do. I suspect this is done by supply different voltages for different functions. Monitor voltage on that wire with a volt meter. I would start with the volt meter set to dc voltage but also check ac voltage if you don't get anything. With the switch in different settings you should see different voltges. If this happens than I would suspect the wiper motor. If I remember right it's controlled by a "pulse width modulation" so a/c voltage may be a better start.

I would still consider checking things out with a scan tool. If there is a bad lift gate sensor or a wrong signal getting to the BCM, the wiper operation will be suspended.

[delcecchi]

A PWM DC signal ought to show up on a DC meter, as a voltage between 0 and 12 depending on the duty cycle. AC may not show the pulse width variation since the signal is always 12 volts peak-peak.

[Jeremy airjer W]

Chrysler uses PWM for blower motor control. It won't show up using d/c on a volt meter but will show up on a/c. It took me little bit to figure out the first one of those I ran into.

[upnorth]

Now to wait til I can get it for a few hours to test. Wife's vehicle.