I have a very weird electrical issue with my 1993 Mustang LX. The car was originally a 4 cyl car that was converted into a 5.0. I just recently bought the car knowing it had some minor issues but not like this.

The problem with the car is while the car is running and I have the headlights on and i turn on the brights the instrument cluster basically stops working but the symbols for left turn and brights come on and half the tach is lit up.

Now with the key off and I hit the toggle for the brights I can here my fuel pump turn on and something in the passenger's side fill up.

Any clues would help or maybe even just a wiring diagram of the fuel pump and the head lights.

Thanks

 

Replace the ignition switch, on the bottom of the steering column.

 

really the switch could cause this?

 

Having a partially melted or cracked up ignition switch can and will send power to other circuits causing all kinds of weird issues. I am not saying its that specifically but I am explaining why it could be.

 

Every circuiit you mentioned runs through there at some point. you might find later that you also need to do a headlight and multifunction switch as well, but for now, bet on the ignition switch.

 

tried a new ignition switch still does the same thing. The switch i pulled out looks fine.

 

Tests, prove out a defective part. Guess from the desk is expensive and silly. Got more money eventually the problem may be fixed. Test. That is the correct answer. Bubba

 

I looked at some wiring diagrams and it showed the brights as being light green with black and fuel pump being Light green with tan. So i'm gonna have to trace some wires.