Hopefully someone can help me...I recently finished a frame-on restoration and am reasonably certain that both brake lights worked when I tested them for the first time after reassembly (although not 100%). Now, only the driver side brake light comes on. I have a CD containing the service manual and my son and I looked at the wiring diagram. To the best of our ability we have narrowed it down to the wiring in the steering column. I did put a new steering wheel on it and can't get the horn to work. I put the old wheel on and the horn works fine. I am trying to get the brake light(s) working with the new steering wheel on. Also, with the key in the off position, I don't get any brake lights when pushing the brake. I also read there is a circuit breaker in the light switch. It is a new light switch at the time of the restoration. We did run a hot wire to the wiring in the engine area to see if the wiring to the back lights was ok and they lit up fine. Any ideas?

 

Ground the tail light bucket to a good source and see if that solves the problem. My brake lights only work with the key on, like yours. NumberDummy says that Ford never made them that way, but there seems to be several of us on the forum that have trucks that operate this way.

 

If I understand your problem correctly, the right brake light does not work, but the left one is OK. My first question is does your right rear turn signal work? The brake light and turn signal light share the same bulb filament and source of power - which goes through the turn signal switch in your steering column. Have you checked the bulb to make sure it is installed correctly and that both filaments work? Checking for a good socket ground (previously suggested) is always a good idea. If the Jim Osborne Reproductions Wiring Diagram is accurate, and that's the one you have, look on page 4. Green wire 282 should be the one for the brake/turn filament. (Brown 285 should be for the running lights. If I got it backwards, someone please correct me.) It looks like there are about five disconnect plugs between the light at the rear of the truck and the turn signal switch. Any one of them could be a loose or corroded connection. You have a disconnect for the t/s switch at the base of the steering column and then the wires go up the column to the switch. Maybe in trying to solve your new steering wheel/horn issue you accidentally caught or disconnected the t/s switch wire that affects your brake light. Maybe the t/s switch has just gone bad. That switch plays an integral role in the brake light function. Maybe your brake light switch on the master cylinder has developed an internal malady. If you think it worked before and just recently quit, I would look in the area where you have been working and that's the column where the horn wiring and the turn signal switch are so close together. Good luck.

 

I had this happen about 6 months ago the left turn and brake light both went out, and then both brake lights went out,, I got a fix it ticket for this, and after a bit of circuit testing it turned out to be the Turn Indicator switch that had indeed gone bad. NPD has a replacement FOMOCO for and ungodly amount, and a non-ford unit for about 25 bucks, half an hour later and 25 bucks I was fixed.. easy swap! the ticket cost me 25 bucks too!