85 f150 turn signal and dome light problems

  Hi all,
My turn signals work fine until my parking lights and headlights are on and then they are barely visible?
also the dome light is on all the time, I have replaced the switches to no avail?
Thanks for your help.

I had the same issue with my turn signals after rewiring my truck. The park and turn wires were switched around. The turn should illuminate the brighter filament. Now thinking about it, maybe you can try just flipping the bulb 180 deg, not sure if that would work. If you recently changed them and have not messed with the wiring, probably.

Since you replaced the headlight switch, check the wiring diagram again to make sure you did not get it wrong to leave the dome light illuminated.

I know I sound like a worn out record here, there is a ground stud behind the radio. The other side of that is a ground stud on the outside of the fire wall that is hooked to the left rear corner of the intake manifold. then is grounded through the engine to the battriey. Everything in these pickups is grounded through these grounds. If any one of these grounds is bad or missing, this kind of thing will happen.

In short check your grounds.

 Thank you , as a matter of fact I just replaced the parking light fixture on both sides, Bingo!

 I'll check it out, been driving me crazy. Thank you.

I must be looking in the wrong place, I don't see a ground wire or a stud in that area, my intake manifold was replaced by one of the 10 previous owners with an Edelbroc manifold and there aren't any wires attached to it?
The good news is flipping the bulbs around seems to have fixed the turn signal issue, knock on wood.
Thank you.

 Unfortunately I cut my first set of wires to swap them around, realized I can just unplug them(on the aftermarket sockets) to swap them on the next set. Guess if I had a third turn signal I would have finally arrived at the easiest solution...  Glad that solution could be used on yours!

I dont know if youve checked this, but there is a setting on the headlight knob that you turn to adjust your dash light brightness. If you turn it all the way, the interior lights stay on.

I had great day on Sunday, I was fooling around with my dome light fixture and had removed it to try and retrieve 2 bulbs that had fallen in the hole and after reinstalling the fixture the dome light went out as it should when I closed the door at which time I tried the passenger door and the headlight dimmer switch
and everything functioned as it should, that lasted for 2 glorious days. this morning I opened the door and closed it and my triumph had ended, it's utterly amazing how something so small can torture you.
 Help!

dennisb wrote

I had great day on Sunday, I was fooling around with my dome light fixture and had removed it to try and retrieve 2 bulbs that had fallen in the hole and after reinstalling the fixture the dome light went out as it should when I closed the door at which time I tried the passenger door and the headlight dimmer switch
and everything functioned as it should, that lasted for 2 glorious days. this morning I opened the door and closed it and my triumph had ended, it's utterly amazing how something so small can torture you.
 Help!

Dang Gremlins!

Forgot to mention, replaced both door switches to no avail, both sides have 2 hot wires?