1975 Ford tail light issue

[Coonburger]

Okay ive been "playing" with this all day and iam bout ready to loose it. Headlights all the markers lights work but the tail lights wont light up. Blinkers work, brakelights work, hazards work. The wiring has been hacked into a few times but i checked the connections and it is sending power up to the bulbs but its just not lighting up. I changed the bulbs. I even spliced into the ground for the bulbs and made another ground to the frame and nothing. All of em have continuity. Bout ready to just order a new harness and go from there but i dont wanna just throw parts at something just hoping itll work.

[Rick]

switch??

[Coonburger]

ran a ground wire from the body straight to the edge of the bulb worked on one side but not hte other. I am currently checking the connections at the four prong plug see if its a issue stemming from there

[Jim]

Could there be a short in the wiring between the bulbs? Any area where wiring routes through a body or frame hole?

[Hypoid]

I'm guessing the socket is corroded. Looks like they are still available: http://www.oreillyauto.com/site/c/search.oap?year=1975&make=Ford&model=F-150&vi=1120688&keyword=tail+light+socket

It's been over a decade since I futzed with the tail lamp circuit on my '74, but I keep thinking the ground for the tail circuits is behind the passenger housing. Anyway, the tail lamp circuts ground at the back.

[The StRanger]

Are you still on the twist in bulbs ????
Clip them off and splice in the new style bulbs..
B

[The StRanger]

Are you still on the twist in bulbs ????
Clip them off and splice in the new style bulbs..
Best thing you can do for yourself !!!

[The StRanger]

Sorry. Doubletap !!!

[CS79bronco]

If the socket is full of the old dried up grease it might be pushing the bulb away from the contact. Also the ground contact in the socket may be separated from the wire inside the plastic. I spent several hours before finding one of those.