E30 Vert rear window defrost motor

[6670charger]

I just realized after a few years of ownership that my car has a rear window defrost motor/fan behind the back seat. It doesn't seem to be working at the moment, but I haven't checked all the usual suspects as yet (fuse, switch). Plan on working on that this evening.

 

If it doesn't end up being the simple solution, how does one go about testing the motor to see if it's working? I assume I can test the plug easily enough once I verify that I have a good fuse and that the dash switch lights up just by touching the body for ground and then testing the pins. I see there is also a relay or circuit breaker on the thing. Any good way to test that? Sorry, but I'm not an electrical guru. It's probably my weakest area when working on cars.

 

I've done some looking online, but don't find much that's helpful. It would be nice to have it working this winter for a change.

 

Thanks!

[6670charger]

So far I've checked the fuse, the switch and the rear plug. The fuse is fine as the switch illuminates when I press it. I'm not getting any power at the connector plug to the fan motor, although I'm not certain that is because there isn't power coming from the switch. The defroster fan motor has what appears to be an external resistor and possibly also a circuit breaker attached to the outside of the fan housing. Again, electrical isn't my strong point, so is there a way to test both the resistor and circuit breaker to see if they're working? My assumption at this point is that since they're there, they must ultimately provide power to the fan which may be why I'm not getting power at the plug. My wiring is fully wrapped and fine as far as I can trace it, as this car was in nearly new condition when I bought it a few years ago with all wiring unhacked.

 

Right now my assumption, until proven otherwise, is that I have either a bad resistor, circuit breaker, fan, or a combination of any of the three.