Power Window Problem

c3garagesc · Oct 23, 2024

I'm working on a 1971 with power windows. The previous owner, for whatever reason, bypassed the safety relay that's behind the DS shock tower and ran a 20 amp fused wire directly from the battery to the DS master switch. Doesn't appear to be any other mods done. I can get the front windows to open and close fine, as long as I have only one of the switches for the rear windows plugged in, but as soon as I plug in the remaining rear window switch, the fuse blows. In checking the power and ground connections in the master switch panel, all power and grounds are as shown in the wiring diagram. Any info or tips are greatly appreciated.
Thanks!

Steve McMahan · Oct 23, 2024

While I’m no power window expert, when you plug in an electrical item and the fuse goes, you have a dead short. I suspect one of the rear switches has a dead short. You can test them by seeing if the power wire to the switches shows an instant ground, using your VOM. Others more knowledgeable will chim in.

Hemikiller · Oct 24, 2024

Which specific switch location causes the fuse to blow? Master panel or a specific quarter switch? Which switch?

The entire power window system is grounded in one place; the eyelet at the driver's door. If you remove and insulate that ground, and the fuse still blows, then you have a grounded wire in the circuit of the specific switch you're inserting. Once the switch at the driver's master panel is inserted, it sends power back to the switch at the remote position.

If the fuse no longer blows, then you may have wires touching in the master panel connector itself.

c3garagesc · Oct 25, 2024

Either master panel switch for the rear windows blow the fuse when one is plugged in and then as soon as the other is plugged in.

Good thought on the ground wires. They seem to be on the door, as you mentioned, and then another to the cowl. I'll remove them and see what happens.

Wish me luck!

The Heff · Oct 29, 2024

I had a similar problem with one of my back windows, when that window was activated from either switch, the fuse blew. Upon investigation, I found the window wiring loom was rubbing against the windows mechanism and shorting down to ground.