Disco Headlights on Bright.... Flashing On/OFF

[67Mach1]

Went for a long drive tonight in my 84 GT350. When I got on a very dark streach of pavement I put on my bright lights. After a few moments they started flashing on and off, On and off, again and again. I dimmed the lights and all was well, I drove home w/out an issue.

Any Ideas?

Thanks,
Thomas

[ZachW04Stang]

Possibly the dimmer switch.

[la.fraude]

most likely. they love to go out. i think mine has been replaced twice so far. idk why they do this, the intelligence know why and why this hasnt been fixed right. haha

[89 AZ SSP]

If you do a search for headlights under this section you should find a answer. I had a problem with my headlights and found many topice covering issues about this.

[82mustang]

i have the same problem and after trying a newer switch it does the same thing still. Do you have upgraded lights(like sylvania silverstars) for the lo(and possible hi) beam? when i put in the silverstars my problem started, I'm pretty sure it's overloading the system causing the internal breaker to pop(if there even is one). The only real cure bring to install relays for the lo and hi beams, basically using the power from the switch(that used to go to the lights) and using that to trigger a relay that sends full battery power to the lights. Doing this will make even stock lights brighter and reduce the chance of a fire..it's on my to-do list

[Syco Stang]

Check the headlight grounds, they are located on both sides of the upper rad support and have 7mm bolts securing them. Sometimes these corrode, and sometimes the actual wires corrode or disintegrate. It could also be your headlight switch or the turn signal stalk. I hesitate to call it a multi function switch because those old cars only had a few functions there compared to the 87+. Let us know what you find.
SS

[negusm]

82Mustang is right on the money.

For a stock setup, replacing the headlight switch will probably fix it (it did for me).

If you have upgraded your headlights, you are probably looking at rerouting the headlight switch through some relays.

The Ford wiring was barely able to handle the load back in the day. Add 20 years, corrosion, degradation, and you're going to have a problem.

And forget about using your fog lights (if you have them), that extra load is certain to cause the headlight switch trouble.

-Mike

[82mustang]

my fog lights didnt affect anything, on or off as long as the hi beams are on they would click off...i tried running only lo beams with no fogs for a while, then clicking on the hi beams and they would shut off again..no difference. Could it also be your ignition slider switch?

[1redcat]

i had the same problem in my 89.i replaced the head light switch and the plastic plug.when the switch heats up and causes it to (disco) it will also make the plastic connector and the contacts swell

[grtskydog]

^^^^yep...Had the same issue with that factory breaker. I have the stock wiring for the headlights, but I've relocated the fog lights to a separate circuit, with bigger wires and a relay...using 100w bulbs. I rarely need the brights anymore.