Window Switch Electrical NIGHTMARE! HELP!

[Sputnik]

First post since 2016...holyshit.

Car in question '91 318is w/ s52 swap
-Long story short... Driver Side window works fine, Passenger window blows the #17 fuse when the Button is Depressed.
-Problem happens even when the window motor is unplugged
-Problem happens when the C404 connector was separated from the door harness.
The Button Lights do glow for both driver and pass side switches

What I've done so far.
-Rebuilt and bench tested window motor
-Check continuity from window switch to the window motor...good
-Check continuity from window switch to the c404 connector....good
-Swapped window switches and swapped window circuit breaker...no change.
-I've looked for frays in the wiring to no avail....but not underneath the carpet since that is my last resort.

What do you guys think? any similar situations, comments, concerns......I'm at wits end, and I want working windows!

[Sputnik]

Also, the windows circuit breaker doesn't pop out when the Pass window switch is depressed, the 30amp fuse just blows instantly.

[tomstin]

Have you checked continuity from the power wires to ground? A screw through a power wire would test good from end to end but still be direct to ground.

[AndrewBird]

Have you checked continuity from the power wires to ground? A screw through a power wire would test good from end to end but still be direct to ground.

This right here. Check for a short to ground.

[Sputnik]

Now, I've ran my probe from the back of the window switch connector to the connector for the window motor with good results.

when you say check for a short to ground, you mean from the connector to the location of the window switch circuit's common ground?
I've probably answered my own question, but please spoon feed me like a baby. I'm probably over thinking this to the Nth degree

[tomstin]

So you checked continuity from each wire at the switch to the window motor connector? Now, from those same wires at the switch, check continuity from the wire to body ground. Make sense? To be safe, each power wire, check end to end and wire to frame ground. Do you have a wiring diagram?

[Sputnik]

yea I've been using one online, feel free to post whatever you have.
It has to be the specific body ground for the circuit or any part of the chassis with bare metal?

[AndrewBird]

Any chassis ground. You are checking to see if any of the wires have been rubbed through or something and are shorting against the body.

Another thing to check is continuity between wires. If there is continuity between two different wires, you know they are shorting against each other.

You should disconnect the battery while doing this to prevent frying your meter or frying something in the car.