Electrical?

Having Problems with the 92 RS I just bought. The fan won't come on and the tach stays pegged out all the time. The Battery is new and the alternator looks reasonably new also but if the headlights are on and i push the brakes everything dims also the stereo makes a funny throbing noise when its turned on.

The tach problem might just be your instument cluster. I had a 90 iroc when I was 19 and he cluster went out and my speedo or tach did not work. Check your fuses, you might have somthing going to ground too. Not real sure but some things to think about

I had the key in the on position and took out the instument cluster and the tach stayed pegged then when I turned the key off then disconnected the tach it went to 0 then i placed it back in and stayed 0 till I started the car then it just went back to pegged out. I think its a ground but I have no idea where to start looking for it. I checked all the fuses and they are all fine. Any ideas?

electrical, exept may be the fan. Just have a relay and a manual switch put in for the fan.The rest is bad grounds, melted wires, cracked insulations,etc. See if anyone messed with the wiring too.

okay mabey I just figured something out, with the key in the on position everything works fine but, when I start the car everything goes haywire. After the car is started for a short time mostly everything returns to normal except the tach stays pegged at least thats all that is obvious. Is there anything in the starter or ignition that could be causing this sort of actions?