1992 Century Electrical Problem

Starting about two days ago with my 1992 Century 3.3L my rear defogger switch now primes up the fuel pump, turns on the warning lamps, can turn on even when the car is off, locks the doors when the car is moving, turns off the dome light, blows the guages fuse, and wont allow the car to shut off (this only happens sometimes). So, I was just wondering where a good starting point would be to fix this problem.

I'm guessing when you hit that switch it's shorting at or near the fuse box and sending power spikes across other fuses to other functions. First thing I would do is take a real close look at both sides of that fuse block and see if anything is melted. I would also make sure you are using the right grade fuses for each slot. If you find nothing there then I would trace the wires from the defogger switch to the fuse box and back the the defogger looking for a freyed wire grounding out somewere.

What happens if you don't use the defogger?