77 F150. When I turn the headlights on, the right turn signal indicator on the dash lights solid and the backlighting does not come on. The right turn signal does not light up outside the truck. If I use the right turn signal, it does flash but slowly. It would appear the voltage for the backlighting is going to the turn indicator but I can't figure out how. Pulled the cluster out, pulled the light switch out. Cleaned and greased both. Traced voltage on the light switch and it looks correct. It's tough to do the same on the cluster with little slack on the wires. Any ideas would be appreciated

 

It the ground at the light outside not in the dash.
At night turn on the running lights answer check the lights on the side that turn light is on in the dash and I bet you will find a dim light at the bad one.
Dave - - - -

 

There are lighting grounds at all four corners. One in each of the taillight cavities, and one for each headlight, which screws to the radiator support.

 

Wow, thanks guys, I never would of guessed that. It was the ground inside the socket for the blinker. The backlighting still doesn’t work but that will be easier to track now.