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Trying to get to the bottom of why my driver's side PW in my 80 is not working. The window itself falls about half way down, and I am able to manually pull it back up completely, but then it falls again. Is this indicative of a failed power window motor? Or regulator, spring, etc.
The switch works. I tested the window motor, with test leads; one from ground to motor case, one from battery+ to each terminal on the motor, and I get nothing. So, I assume (if I'm testing it correctly), that I need a new motor. But is the glass falling down a separate issue? Or does a dead motor not keep the glass in the up position?
And also, any recommendations on a good source for a replacement motor? Prices seem to range from about 50 to 100 with shipping
I think I got the motors for my 79 from RockAuto - these motors aren't anything unique. However, it sounds like you might have a mechanical issue also, if the window can be pulled up by hand, and then drops down again (assuming that it does this with the motor still attached?). Also make sure you test the motor by grounding the case, and then applying voltage to one of the connectors. If I remember correctly, one of the connectors causes the motor to go up and the other connector causes it to go down.
I think I got the motors for my 79 from RockAuto - these motors aren't anything unique. However, it sounds like you might have a mechanical issue also, if the window can be pulled up by hand, and then drops down again (assuming that it does this with the motor still attached?). Also make sure you test the motor by grounding the case, and then applying voltage to one of the connectors. If I remember correctly, one of the connectors causes the motor to go up and the other connector causes it to go down.
Yep, with the motor attached. And that's what I was wondering- whether or not it's a mechanical issue in addition to the motor. Kind of sounds like the spring? Although I was able to see the spring with a small mirror and it looks normal (still attached and not broken).
"Also make sure you test the motor by grounding the case, and then applying voltage to one of the connectors. If I remember correctly, one of the connectors causes the motor to go up and the other connector causes it to go down"
That's exactly how I tested it. No sound from the motor, no movement anywhere..dead.
OK, so motor might be dead. However, even with a broken spring, the motor itself should hold the window in position (with the motor gear making contact with the 'gear' portion of the regulator. I'd remove the motor (and check it again while out). Maybe it's possible that something broke, and is jamming the motor gear? For the window to move up and down freely, I'd suspect that maybe one of the guide wheels broke off?
OK, so motor might be dead. However, even with a broken spring, the motor itself should hold the window in position (with the motor gear making contact with the 'gear' portion of the regulator. I'd remove the motor (and check it again while out). Maybe it's possible that something broke, and is jamming the motor gear? For the window to move up and down freely, I'd suspect that maybe one of the guide wheels broke off?
hmm... maybe the gear is stripped in the regulator or motor. Or both. Not looking forward to removing it to see- I am a little concerned about the spring letting loose. I know a bolt can be inserted to prevent this, but I'm not sure I can get access to the hole to put the bolt though because the window doesn't work.
I had my passenger side all the way apart. Without diving too far into the above posts, possible reason for your results:
stripped worm gear on motor
stripped gear (the big round one) or the smaller one that engages the regulator teeth
stripped regulator gear teeth
bad/missing bushing on the back of the gear. This is what holds the gear in the motor in place.
they make fixes for them all. motor is as mentioned 50-100. round gear is almost 40. kit to repair the regulator is 21. bushing is 9 or whole plate/bushing 17.
Grounding the case does nothing. You have a reversible DC motor. Hook a power and ground to the terminals and see what happens, then swap the wires and check again.
If the motor doesn't work, ground a test light, actuate the up/ down switch and check for power at the harness connector. Should have power to each terminal, corresponding with the switch position.
I could be completely wrong. But I don't believe the motor is case grounded.
If you have power, and the motor doesn't function, it's motor time.
Not an expert on window regulators, but on the ones I have worked on, if you can pull the window up, it usually means a roller or two are broke/ out of place etc....
I would strongly recommend a factory service manual. And an assembly instruction manual (AIM).
Hope this helps.
2025 c3 ('74-'82) of the Year Finalist - Unmodified
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There are two terminals on a Corvette power window motor.
Applying power to one sends the window UP.
Applying power to the other sends the window down.
The motor case must be grounded or it will not work.
Thanks for the diagram. Shows case ground.
All the window motors on the vehicles I work on, have the two terminals, but the switch reverses polarity.
Thank you for correcting me.
Jeff
Power window testing
Smart guy.