I have a 1987 BroncoII that started a very interesting problem. I have noticed that when I am driving the vehicle or when the vehicle is parked, the headlights (sometimes) turn off both at the same time, and then seem to come back on in repetition! It’s as if they do this with a steady repetition. No other lights or lamps are affected on the vehicle, only the headlights.
Obviously I can’t do this test while the vehicle is in motion, however when I am stopped (makes no difference if the key is in the ignition, or high or low beams are on), and I disconnect one of the headlight connectors from one of the headlight lamps, the other lamp then stops the repetitive “flashing” on and off. I then re-connect the headlights connector and they both start to flash off and on again simultaneously together. When I unplug the other headlights connector the same condition occurs (the other headlight stop’s flashing), when I re-connect that other headlights connector then they both start to flash with the off and on again in repetition.

The condition I am describing existed before the below paragraph. Below is another example if an issue since I have noticed this headlight problem.

About two months ago I needed to pull a small trailer with some household belonging to another city with a borrowed trailer. I went to the local trailer place here in town and got one of those in-line electrical connectors that go in-line with the factory wiring in the taillights so I wouldn’t have to splice or butcher any of my wiring.
I noticed that when I was driving the vehicle with the trailer attached the turn signal’s wouldn’t work unless the headlights where turned off! With the headlights on (as required by law here in Alaska) the turn signal wouldn’t flash.

If anyone could point me in the right direction to look at I would appreciate it very much. I know that this is a little long winded, but I find it hard to believe that I could have two electrical defective headlamps. I have a suspicion that my flasher might be involved, but I don’t think this would explain my headlight issue. It is driving me a little crazy, and I don’t want to throw a lot of money at this, not at 244,000 miles anyway.

Best regards,

John from Alaska…………..

 

Sound like your defungalrter is crossed wit your configulater and ther both ground to the debogalater. j/k

Sorry man I had to do it. I dont have clue what is wrong with your truck Good luck.

 

There isnt much to this circuit, just a fuse link the dash switch and the dimmer switch. Sounds like the dash or dimmer switch is intermittant. Maybe one of the other guys will know a good way to test this.