Need Help with Power Window

[BryantRiverRat]

I have a 1978 with Power Windows, the doors and switches and motors are off of a 1981-85 chevy truck. The Door Locks Work, The Windows Do not work, I have 12 volts at the switch, so I bypassed the switch and nothing, BUT if I bypass the switch and use a 18v battery from a drill the window goes up and down very nicely....what in the heck would make the 12v system not work the window at all either with switch there or bypassed.

 

[85-K5Blazer]

Have you studied the wiring schematic for the trucks in the 81-85 era ?

Go to the Technical Section and pull one from the 81 - 85 section and get the wiring catalog and review the schematic.

It sounds like possible a bad switch, bad harness, or a poor ground .

If your getting power to the switch but not functioning, it sounds like that is the issue.

Replacement swithches can be purchased all over, Rock Auto, LMC, ETC. You can purchase a new switch harness from LMC and you will have to splice it in but it is not that bad ... I replaced my Passanger Side harness when the power lead broke going into the plastic harness.

 

[88Silverado]

I would pull out the regulators and motors and make sure they are not gummed up. re-lube and install the LMC or equivalent window motor relay kit and be happy.

 

[kennyw]

GM power windows work via switching the polarity at the motor. This means both power and ground are being switched at the same time. So, you will want to verify the ground is good at the switch harness in addition to the power. My guess is you have a bad ground.