<hr size="1" style="color: rgb(209, 209, 225);"><!-- / icon and title --> <!-- message --> My center high mount brake light isn't working. I drive a 2010 F350 CCSB. The lights on either side (cargo lights) work but not the brake light in between them. All wiring for the lights comes in from one wiring harness. I have replaced the bulb, it didn't work. I tested the fuse, its good. I tested for power at the socket, no power. I'm thinking bad ground. What do you think? Everything else is working perfectly.

 

According to the diagrams, all the bulbs in that unit share the same ground. Also the diagram says there are two brake lights and one courtesy light.

The high mount brake lights are fed with a yellow/green wire. That comes from a stop lamp relay in the underhood fuse box. From there it's fed from fuse 12 in the underhood fuse box, 15 amp. Check that fuse. Not in the underdash fuse box but the one with the engine.

 

The diagram isn't right. I have one brake light and two cargo lights. The hot wire is yellow green but my manual says an under hood relay runs the third brake light along with many other things that still work. I'll check fuse 12 under the hood just to be sure. Thanks for the reply.

 

Got it. #12 fuse under the hood. Weird, the manual had it listed as "brake switch, (BOO)". Thanks for the help Dave.

 

Glad you got it, even though the diagrams seem to conflict. That happens alot.