My buddy's '97 has slowly been degrading electrically. At this point, the windows, speedo, tach, A/C, and blinkers don't work.

It was also having a problem starting, so we replaced the ignition switch. This fixed the starting problem, but nothing else. All the fuses are fine. We're stumped, any ideas?

 

Did you check all the relays? I'm thinking that with so many problems you might have bad grounding that screws it all up. Or, I'm not sure on this one, you can have a voltage regulator messed up. My friend with a 98 had problems with all the back lights.

 

All of the relays in the engine bay are fine. All of the ones under the dash are fine (that we could find).

 

With the car running, check the battery voltage. Should be near 14V. With the engine stopped, should be 12V+.

 

Are your grounds good?

 

I would check the battery, alternator, and all the ground wires.

 

This sounds like it is a number of problems that are probably unrelated. Probably best to try to fix one problem at a time. Maybe try and fix the simplest one first. If they are related and you fix the easy one maybe you will get lucky and fix all.

Easiest to fix is probably what you call blinkers but what do you mean? Turn signals don't work? Hazard flasher does not work? Both? Try to give more detail about what is happening or not and maybe someone can give you some ideas.