i have a 77 f150 4x4 my blinkers work good when the lights are off. but when i turn the headlights on the left blinker at times either blinks really slow or not at all. and it doesnt do this all the time. i was wondering if it was the switch or where to start looking. thanks

 

Probably not the switch since it's working. If you won't to do it right pull the instrument cluster out. Clean the paper circuit with rubbing alcohol. Clean all contacts and where the main cluster plug goes in. The replace your blinker bulbs. Plug it back in and see what you got.

 

This is a textbook case of ground shift in the bulb socket itself. Replace both front turn signal sockets.

The cluster is not related to the issue.

 

I concur, I had the same problem a wile back with the rear. I replaced the rear harness problem was solved...hope all goes well

 

the reason i think its the switch is because if i wiggle the switch a little it starts to work

 

Hey did you resolve your turn signal issue, and what fixed it?

 

Did you resolve your turnsignal issue? If so, what was the problem. I have the same truck with same issue.

 

The guy I bought mine from had replaced 2 of the sockets. I replaced the other 2 and still had the same problem. After checking his work, I found he had wired one of the sockets backwards.