Recently, my 96' F-150 began displaying strange turnsignal symptoms... All bulbs appear to be good, and the 4-ways work great... but the turnsignal problem seems to be intermittent. The signals work good, then all of a sudden, the dash indicator stays on "solid", left or right... after awhile, they blink normally... and all of a sudden, solid indicators again! And yesterday I noticed they were flashing, only not in rhythm... a couple of normal flashes, then a really slow one or two, then solid, then normal again for awhile. My owners manual shows one relay each for right and left turnsignals, in the relay box under the hood. Should I replace them both, or is there another "hidden" relay or component I could be suspicious of? The turnsignal switch itself? This is frustrating AND dangerous! Any input appreciated!

 

There are two relays (flashers). One is for the turn signals and one is for the four ways. I would THINK they are ok but the turn signal one might be bad. You can maybe try switching the relays to see if the problem changes itself.

Also, check your bulbs. Make sure they are all working good. Another thing you may want to check is your trailer wiring, if equipped. My dad had the same problem and his trailer wiring was screwed up (grounding out?). Good luck!

-Matt

 

I would take the bulbs out of the offending side of the truck, and clean them and the contacts inside the socket. Also while you have the bulbs out, hold them up to the light to you can see the filament inside them, and tap the bulb with your fingernail. Sometimes a filament will get loose on one side and make connection sometimes, and sometimes not.

 

That's what I was getting at but couldn't say. Also, if the filament is touching across the running light filament it can cause issues. Does it do this with the running lights on or not, or does it make a difference?

-Matt

 

I know this is an older post, but I had turn signal issue that was resolved by replacing the bulbs. I forget which side was causing the issue on my 96 F150, but when the lights were on and the cruise was on, when using the turn signal, the the cruise would disengage. Replacing the bulbs fixed it. When a trailer was hooked up (factory towing package), the other side would disengage the cruise with the lights on. One side had the turn signal out, the other had the running light out.

 

Thanks for everyone's input! Learned a lot, but in this situation, it turned out to be the turnsignal flasher. All systems work like new after replacing it. Thanks again!