Turn signals don't work when headlights on???

[67F100-390]

When the parking lights or headlights are on, the turn signals quit working. When I turn the lights off, the turn signals start working again. All the bulbs are good, and the hazards work. What could this be?

[70_F100]

Sounds like you may have a bad ground.

[67F100-390]

I just tried them again, I turned the turn signals on and they worked, then I turned on the parking lights, and the turn signals got slower and slower until they quit working. I got about 3 blinks out of them with the parking lights on.

[67F100-390]

Where would I begin looking for a ground problem?

[fordman]

if it is a ground problem. the frotn bullbs groudn to the core support behind the headlight. and then through the body. the rear tail lights ground to the tail light housing which ground via the housing screws and bed. the bed grounds to the frame. i am unsure about what the problem may be.

[67F100-390]

since the blinkers worked today with the parking lights on, it leads me to believe that it might be the flasher relay

[67F100-390]

So, I got the turn signals to work with the parking lights on. I took the flasher relay out, sanded down the ends that bolt to the body and bolted it back up. It started working... for a little while. But I still couldn't get the flasher to work when the headlights where on. (not even one blink) I took a flasher unit (out of my engine donor - 71 F-250) and tried that. But it was the same. Also, why is the flasher unit out of my 67 so big, square and loud? This has factory part numbers on it... C7TB-13350-A and the flasher unit I took out of the other truck says heavy duty uni and small, round, and quiet?

[fordman]

it is a combination turn signal and hazarcd flasher unit. it is a one of a kind. they are very hard to find too. specially if you have a early 67 like my wiring harness came out of.

[67F100-390]

Anybody have any idea's?

[70_F100]

Double-check, no, TRIPLE-check your grounds...

And if you need a new factory replacement flasher, send me a PM.

[67F100-390]

I did notice in my wiring diagram, that the turn signal and headlight grounds connect together. I will take another look at the grounds.

[67F100-390]

Finaly figured it out. Its my combination turn signal and hazarrd flasher unit. I took it apart and bent the arm that moves up and down until it was in perfect spot to move correctly. At first I bent it to far and it flashed super fast and then quit. Then I bent it a little bit the other way and now it works perfectly. So I'm going to replace that part and be done with it.

[67F100-390]

I found another problem in the process. I took the grille off to get to all my grounds (and to take the turn signal housings out). Once I got everything cleaned up and all the wires hooked back up, I didn't have either of the parking bulbs working. Finally I hit the housing with the end of a screw driver (on the bottom to be exact) and the bulbs light up! When I went to do the other side, I tried to wiggle and pull the wires but had no luck. So once again I hit the turn signal housing again and they started working. Hitting it only worked if I hit the bottom. Is this something I can fix? It doesn't make sense to me, I would think that the wires might be sending the bulbs a loose connection... but that isn't the case

[fordman]

sounds like bad sockets. yo ucna pull the inside out of the socket and spread the sprign. but that may not help. if the terminal ends are worn down. if they are worn down you can get trailer light replacemnet guts and use them in your housing to replace the worn out terminal ends.

[67F100-390]

Just by pulling, or do I have to twist also?