is window switch failure common & how to test

[Bizzyboy904]

I have a 91 318i and all 4 windows don't work. I've noticed that a lot of people sell window switches and I was wondering if that part failed often? I saw the write up on how to test the motors and I will check all four today, but does anybody know how to test the window switches?

Thanx

[dnguyen1963]

Take the switch out and give it a good cleaning. Bend the tabs out so it would make a good contact with the base and you are good to go for another 20+ yrs.

[Madhatter]

this is frequently the problem.



If you get yourself some contact cleaner and some fine grade sandpaper (1000-1200) or a scotch brite pad, you can clean up the contacts on the switches and the tracks they run in. You don't really need to bend the pins to make good contact, it's usually just enough to clean them up and remove the gunk.





The only issue you can come across is the contact pads on the bottom of the switch. Those are the round tin contacts you can see in the photo directly above. These do wear out from use and leaves a deep hole in the contact which the under side of the button cannot touch. If this is the case you can try brazing some more metal on to it to build it up. Solder is messy and doesn't like to stick to the contact, so to be honest I think ive only seen maybe 1 out of 10 that was worn out and wasn't making good contact. So id just throw it in the bin and head off to the wreckers/parts recyclers and grab another used one and clean it up.

[Semblance]

Have you checked the window circuit breaker switch on the console? It would explain why all 4 aren't working...

[Bizzyboy904]

Cleaned up the switches and the front two windows are working now?!!! The rear windows still don't work I got to take the window motor s n test them tomorrow

[Madhatter]

Just swap switches front to back first to make sure its actually in the regulator and not in the switch or wiring.

[Bizzyboy904]

I did swap switches that back window s still won't work.

[tonight, we ride]

Did you check the circuit breaker switch that's only for the two rear windows?? Should be the smaller of the two breaker switches.

[henryki]

my left rear window wasn't rolling down, looked at the harness and sure enough the wires were split. get yourself a voltmeter and start off there to make sure you have continuity from the front switches to all the window motors.

[Madhatter]

Did you check the circuit breaker switch that's only for the two rear windows?? Should be the smaller of the two breaker switches.

It only disables the rear door switches though. The front pair still work and should be able to operate the windows in the back.

[tonight, we ride]

It only disables the rear door switches though. The front pair still work and should be able to operate the windows in the back.

My mistake! Thanks for the clarification.