was pulled over tonight in my '78 F250 and the deputy said " Im sure you already know it, but you dont have any tail lights." "NOPE, sure didnt!" Break lights work, blinkers work, and e. flashers work. fuses and grounds are all good and cant find anything unpluged. started looking at the electrical schematics in one of my books and it lists a "rear marker lamp relay". to tell you the truth I have never heard of one going out. anyone have any ideas?

 

Never heard of any trucks having a rear marker relay, except maybe a dually model.

Do your front marker lights work? Most trucks have one single brown wire that comes from the headlight switch, and feeds all the marker lights, front and rear. If your front lights are working, that means the fuse and the headlight switch are ok, and you must have a wiring problem to the rear.

I would try to find the brown wire feeding the rear lights, and poke it to see if it has power. A good place to look is any trailer plug wiring that might have been done that is not factory. This is usually where the problem is if it's only a problem with the rear lights.

 

Found it. I installed a new trailer plug earlier this summer but I soldered all the connections so I wouldn't have any issues. As luck would have it the square plug on the tail light harness is bad. Thank you for the response.