Fuse or Relay

[Cody D]

A couple weird things happened when I was tuning my car... the heater fan, interior lights, and stereo all lost power, and the headlights won't shut off even with the ignition off unless I pull a certain fuse.

I would have thought it was just a fuse, but the headlights not shutting off is weird, and I've never seen anything like that before.

 

[Cody D]

It turned out to be the 100A alternator fuse, but I still don't understand why my headlights wouldn't shut off.

 

[luv2rallye]

It turned out to be the 100A alternator fuse, but I still don't understand why my headlights wouldn't shut off.

The only way is if the headlight relay got stuck on or the ground side of the relay coil got connected to ground (which is how the light switch turns it on).

 

[luv2rallye]

Another strong possibility is some of the wires in the engine fusebox are shorting, melted, or cut. Remove it and look under there or you will probably see weird problems again.