95 F150 4Wd- When I plug in a trailer with known good lights, I can drive with all lights functioning. However, when the engine is shut off for the first time after trailering and restarted, the fuse for the transmission interlock fails. Any ideas where to start? I'm assuming I have a short or bad ground in my truck trailer connection, but it was recently replaced.

Thanks.

 

Do you have a brake controller? Have you added a wire to the red/lightgreen on the brake pedal switch? If so, take this wire off temporarily and see if the problem goes away. Or do you have a factory tow package and wiring harness? Or did you just tie into the rear harness with your own plug with no brake controller?

The shift interlock is fed from the brakepedal switch. There is also lots of other things connected to that one point too, including the brake lights.

 

No brake controller, and it is not a factory rig. It was on there when I got the truck a couple years ago. It appears that they just spliced the harness into the tail/brake light wires...

I suppose I'll just pull the wiring and get a new kit and do it right.