For some reason every once in a while my turn signals stop working and when activated left or right signal will begin to flash as if I have the hazards on. The front continue to work properly but the back will flash. I thought it was linked to the fuse panel under the hood (1955 F100) but I'm not sure anymore. The weird part is that sometimes they will work properly and other times they will flash. Has anyone had this issue before?

 

My cyber space guess, ……poor / intermittent box ground for taillights, try a temp ground wire / jumper from the taillight housing to the frame for a month or two.

 

Do you have the type of signal switch that is built into your steering column, or one that is clamped on?

It sounds as though the switch is starting to go out (short), or you have a short/bad ground somewhere in your back light wires!

It could also be that you have a bad ground forming on one of the back light sockets and it it cross grounding back through the other light. Does it do this when you try to use either signal, or just one in particular?

Brake lights work ok, right?

 

Turn Signal is clamped onto the column. When they work (right and left) both are fine but when they don't work if I put on the right signal both flash and the same with the left. If i put on the hazards they flash correctly. The brake lights work and the running lights work.

Maybe the switch is going bad, I think I will take it apart to make sure all the wires are connected.

 

Just opened the switch and tested right and left signals and the light tester is indicating the switch is working.

The weird part is that when I turn on the headlights the rear singals work as they should. Turn off the headlights and they both blink when either the right or left signal is on.

Any thoughts?

 

So I would assume (dangerous I know) that the malfunction is happing now? Try grounding the taillight housing to the frame, (jumper cables)?

 

Try flip flopping the wires on the right light. Also check the grounds on both back lights. You either have the wires crossed or have a bad ground in the back lights.

 

It sounds simple to me: Turn signals are supposed to flash! LOL

 

I think the solution to your problem may have been mentioned previously in this post. Like 3 or 4 times. Check your grounds at the taillights and run a new dedicated ground wire if necessary. A bad ground can cause all kinds of freakiness in a DC system with a common chassis ground. The current signals want very badly to make a complete circuit and will take any path they can to get there. Sometimes that means backfeeding through another circuit. That's exactly what you are seeing.