I am very frustrated with my turn signals on my 1991 F150. The signals are not working. I have changed the turn signal switch and replaced the flasher. THe hazard lights are working correctly. The brake lights are working correctly. When I step on the brakes and then use the turn signal, the lights on the rear go off until I turn the signal off.

Can anyone possibly point me in the correct direction of what may be causing this? Is there a fuse that I have failed to check?

Thanks!

 

I had a similar issue on my old ranger. Turned out it was a connection near the rear bumper. Something was pinched and caused my turn signals to stop working. Have you checked the connections in the back?

 

Possible. What fuses have you checked?

 

I have not checked the connections in the rear. I will take a look at those.

madpogue I have pulled the fuses that I thought it was. Maybe I should just pull them all and check. I wish I new which fuse in particular would be affected.

 

since you have voltage going to the lights, a fuse is not going to be the issue.
think ground ... it's possible that the socket that hold the bulbs are somewhat decayed. check those and make sure that your connections are clean as well.

 

Um, WRONG. The bright filaments in the rear bulbs come on from THREE different sources - turn signal, emergency flasher and brake light. Those are energized by THREE different fuses. The OP reported the lights working with the brakes and emergency flashers. That means those two fuses are good. That says NOTHING about the turn signal circuit.

To the OP - fuse assignment is in the owner's manual. Are the front signals out as well?

 

Here is a wiring diagram for you truck's directionals.


https://www.ford-trucks.com/forums/9...-question.html

 

Sounds like yo have a grounding problem. Check wire harness under truck at rear near turn/brake lights

 

Yes the front signals are out as well. I think that I will go in the following order of testing:

1. Change fuse (I think its fuse 5 from what I have looked at online) -- Easiest possible issue
2. Check bulbs for corosion/decay/connectivity -- Second easiest
3. Check connections at the rear
4. Check individual wiring routes from the switch.

 

Bulbs / rear connections are __most likely__ good, since they work with the emergencies and the brakes. (underscore _most likely_; with Ford electrical systems, you never know). So for order of priority, after checking/changing the fuse, I would focus on the turn signal switch next; as the above-linked diagram nicely illustrates, the combinations of contacts that open and close with the various switch positions are....interesting.....

 

It was the fuse. Problem solved!