Passenger side electric window does not go up or down from either switch

The odds of both switches going bad at the same time is high, remove the door panel and tap on the window motor with a hammer, while trying the switches. I may have jammed up. Ground a test light and check the motor connection, while trying the switch, power will show on either side depending on if it turning up or down

The master switch is the one located on the drivers side. If this switch has a malfunction it can rob power from the passenger side causing the problem you have. If the regulator/motor are in working order and you know the passenger switch is ok then that could be the problem. Another couple of possible problems could be a broken wire in the harness traveling from the car to the door (inside the rubber protective boot or a weak window motor (1990 is pretty old for a motor of that type.

Need to get a wiring diagram. Buy a book and follow the wiring schematic. It should help you out majorly. Can't really work on electrical issues without one.

It sounds like everything else and the wiring is okay, only that button on the driver's switch is not working. I would try a new switch, if you see nothing wrong with the electrical plug for it when you take it off.
If that down wire was broken somewhere from the driver switch to the passenger door, I don't think the driver's switch would work for it either way, up or down. And same, neither would the passenger switch work. I think the button for down is not making contact somehow, and right in the switch.

That sounds like the switch is failing to me. Many times these switches get wet and or dirty which causes them to fail to make a proper contact. I have sprayed many of these switches with electrical contact cleaner and seen them work like new. I would try that first before replacing the switch.

Reverse your test light connector, connect it to power so you can check for ground at window motor, flip switch up or down should have ground at both wire's while flipping switch to up or down, more then likely your not going to have ground at the up position, do same test at harness before passenger door switch if no ground master switch bad.

They are ELECTRIC....... things happen like this......When the contacts don't touch they won't move. Try taking the switch from the door the window is down and wiggle it or clean the contacts...good luck. Replace the switch..'gona give you trouble down the road again !!!!!!

The main control switch on the driver door may need replacing, first check and see if the wires to the passenger control on the main switch is properly connected

if the fuse was an issue then all the windows would be inop, not just one, the most common fault is the electric motor that runs the window up and down.

get a switch for pass side