Hi guys,

My truck failed an inspection because of the high mount brake light not working. At first I thought it was just a matter of replacing the bulb. However, that did not resolve the issue. The tail lights work just fine when I press on the brakes, the turn signals work so I don't think it has anything to do with the MFS and the fuse is fine as well. I also switched the bulb with a known good one and it still wasn't turning on. I connected a multimeter to it and it is getting power (about 11.3v as opposed to the 11.7 for the 2 cargo lamps on either side of it). I did noticed that the cargo lamps were a bit intermittent, they seemed to need to be position a certain way to turn on, usually how the bulb was pushed on. I tried playing with the brake light but couldn't get it to work.

What should the multimeter be reading for the brake light? I thought I read 12v somewhere, so it might be just low enough to not power the bulb. What else should I be checking?

UPDATE: To whom it may concern, I was testing against an LED bulb. I swapped it with an incan and it worked just fine. I'm guessing that there wasn't enough power to light the LED up. I'll just keep the incan for now to get through inspection. Guess my question now is why is this happening? Sockets going bad?

 

An LED uses only a small fraction of the power of an incandescent bulb.