Running down three windows at once can be considered normal, so the circuit is designed to handle that. Even if a fuse did blow, it should not cause everything to be dead. A better suspect is to follow the smaller positive battery wire to the under-hood fuse box and be sure that connection is clean and tight. Most vehicles had an under-hood fuse box by 1991 so I am guessing yours does too. If not, I will have to dig up a wiring diagram.
Given the age of the vehicle, also follow the smaller negative battery wire to the body and be sure that one is tight and not rusty.
By the way, since power windows are considered a safety system, they are protected by an auto-resetting thermal circuit breaker. Once they cool down for up to a minute, they will reset, but if they have tripped numerous times they can develop arced contacts and prevent proper circuit operation. The windows are the only system that would be affected.
Wednesday, July 20th, 2016 AT 5:26 PM