window switch in my 1990 toyota camery doesnt work

I take it this is for the drivers side door? There should be a constant hot wire to the switch. See if it has 12 volts going to it. If not, run a jumper from the battery and see if the window will go up and down using the switch. If the window moves, then you know it's a power issue to the switch. If you found no power to the switch, that means there is a broken wire. Probably in the harness between the door hinge and the front fender. You will have to cut into the rubber boot and inspect the wires. If you do have power to the switch, then you either have a bad switch or bad window motor. You can still jumper the hot 12 volts from the battery to the other wires on the switch, That should make the window go up or down.

I was thinking very similar to the testing idea. I was thinking multimeter and checking the plug at the master window switch. my trouble was with trying to determine which wire was going to which window that you wanted to check. I had a wiring problem when a number of things cumalitively happened. the tailight filled up with water, I pinched a wire at the trunk hinge, and a no brake light/later found out burnt lamp warning circuit box... well, all this has led to a strand of melted wire from the fuse box to a splice connection and plug to the "the key is in the ignition switch". Since my passenger rear window only works for the down and not the up, I unplugged it 2 years ago. Now with the other wiring debacle... I figured I would pursue this issue, as a finale. DILEMMA: How to trace the wire from the master switch to the rear passenger window for the up. Yes, everything else works; motor, switch, window. All checked out. Is there a wiring diagram of the plug out there???