My center brake light went out a month ago. Thought it was the bulb so replaced that, still didn't work. Checked the fuse and its not broken so my guess was electrical?

Hasn't come on once that I know of but I was randomly walking behind my truck and the light was on. Truck was off lights were off and key wasn't in the ignition.

Went and turned my truck on and turned the lights on and the cbl stayed on. When I switched my lights off it went out and stayed out.

Now I'm definitely thinking wiring but not sure where to start fixing?

Oh and it's a 1990 F150 XLT

 

Take the sill panel off and pull up the mat on the driver's side along the seat area and up the driver's side between the back of the door and the driver's side of the rear window. The wiring goes along this area, and sometimes corrodes and shorts out in behind the seat and along the bottom of the door sill area.

The wire you are looking for is a lightgreen wire. It comes right off the brake light switch on the pedal arm. It splits and goes to the steering column and straight up to your rear brake light. It also splits off and goes to the cruise system if you have that.

 

So turns out they didn't start putting cbl in these trucks till like '96 and mines actually the cargo light. Ha. My bad. I did fix the wiring though and it works now though.