My 1989 iroc z makes a clicking sound when I turn the key.Lights work, windows go up and down, radio turns on ( it resets every time the key is turned). Sometimes it starts after a few tries sometimes it doesnt, oil guage also jumps when the key is turned as well. Previous owner re-wired some stuff ( he put a switch to turn on/off the fan) I've been doing some reading here and by what I have read it sounds like the ignition switch but I wanted some other opinions before I proceed to get that changed. I suck when it comes to electrical stuff, any help is greatly appreciated!

 

Battery would be first thing to check , could be on the way out
Has enough power to turn on light loads like the lights but not enough guts to engage the starter .
The fact the radio resets shows the starter is sucking all available juice out of the battery to the point
the radio turns off from having no power
If clicking is from the engine then the starter solenoid being operated but there is not enough power in the batt
to turn the starter over
If battery tests out good then your Alt may not be charging the battery .Get it tested also
When you have confirmed both those are good then it could be bad /dirty/ loose connections at either end of the thick cables
coming off the battery to the starter ( Pos Red ) and engine (black Neg )
Remove , clean terminals well and reinstall tight
Process of elimination