Who knows how power windows work?

[HeatRaveR]

I have an '82 280ZX Turbo with a strange intermittent power window issue. The driver's side power window rolls down consistently and smoothly all the time. However, when I try to roll it up, it intermittently fails. I do not hear the motor even attempting to roll up (it will continue to roll down just fine). I see a couple wires (green and green w/black stripe) coming out of the switch, leading to the window motor. I tested voltage when I attempt to roll up and am indeed getting power through these wires that lead to the motor, so the issue doesn't seem to be the switch.

 

But as I said, the fhis failure to roll up is intermittent. It'll just randomly be able to roll up again, as strong as the day it was made. So does anyone have any suggestions or ideas of what the issue might be, or how to further diagnose it? Are there other wires I'm missing? Thanks!

[randy 77zt]

Check with a test light at the back of the switch.The system works by swapping the polarity on the window motor.The window motor is not grounded where it mounts.

[HeatRaveR]

Am I understanding you correctly that there are 2 wires that go to the motor, and, for example, going up should see Wire 1 = Positive and Wire 2 = Negative, and going down should see Wire 1 = Negative and Wire 2 = Positive?

Edited May 13, 2014 by HeatRaveR

[randy 77zt]

Correct

[(goldfish)]

Almost sounds like a motor with a dead spot, The weight of the window going down let's it push through.

[HeatRaveR]

Update: Thanks Randy for the info. Once I understood the switching of polarities, I was better able to interpret the readings I was getting. Sure enough, the voltage output when I pushed up was practically nil (when it was misbehaving). I discovered that, unlike most switches nowadays, the window switch could actually be opened up with a couple screws. Inside, I found a pair of levers that rock one way or the other to change the polarity. The contacts were a little blackened from years of use, so I cleaned them up. I did some testing with the switch open and with me pressing directly on the leavers with a probe. It was still acting a little inconsistent, so I thought maybe the contacts had worn away enough that I should bend one of the levers slightly closer to make better contact. I then tried just swapping the levers with each other. So far, so good. I'm still not 100% if the issue was dirty contacts, or not making full contact, but it seems to be working consistently now. (Of course, once it'll probably malfunction again as soon as I put the door panel back on, haha)