We have an insanely low mileage 97 F150 4x4 3 door and its been a great trouble free truck.

Then after a recent (2nd) hookup, the tail and clearence lights quit on our "new" and restored 71 Lo Liner... so out came the test light and meter to find no power to the recepticle's 11 O'clock pin.

That led to going to the book and finding a position 1 "fuse" in the power distribution box on the fender well... hmmm its pins are arranged perpendicular not inline and it is not tranparent. Its a diode.

So... what would cause it to fail?

The trailer lights are LED (clearence) and incandescent (tail).

Thanks!

 

You've got the wrong item in the fuse box. The diode in the #1 diode position is for the ABS system, you need the #1 fuse. See owner's manual.