Weird headlight problem (Resolved)

[Tinstar]

I have an unusual problem with my high beam headlights flashing. My equipment is 1994 Allegro Bus, diesel pusher. I have four headlights and when driving at night my last couple of trips, every now and then when driving with my brights, they go off for a few seconds and then come on for a few seconds. It's not like a loose wire because it is so consistent on the timing and rough or smooth road makes no difference. The dash lights, clearance and tail lights also go off at same time as the headlights and they come back on with the brights. With just the dim lights, there is never a problem.

I got a little excited the first time it happened. I was out in the country on the highway in a driving rain, no ambient light anywhere, driving about 60 MPH and suddenly NO LIGHTS. After a couple of seconds and braking pretty hard, I hit the dimmer switch and all was well. I originally thought the rain caused the problem but it still happens every now and then and it's been months since the first time it happened.

Now I'm thinking the headlight switch itself may be the culprit. I guess since all lights that go off work from the headlight switch itself, it's the logical common part in which to look. I thought I'd ask if anyone has ever encountered a similar problem before replacing parts that may not resolve the problem. OH, I haven't found a headlight relay, but if that were the problem, I wouldn't think the tail lights and clearance lights would go off.

HELP!!! Anyone????

[zman-az]

Tinstar wrote:
Well, I guess that fixed it. I drove with my bright headlights on to and from my trip. They didn't blink at all as best I can tell. The dash highbeam indicator would previously flash with the lights but I didn't catch them doing it at all. I guess the new switch was all that was wrong.

Just saw this thread. I had this same problem with a car I had in the past. Ended up being the headlight switch. I guess the switch has a circuit breaker built inside that is heat activated. When it gets hot the lights go out, while off it cools down and repeats the process.

[Jagtech]

Good work! Glad its solved. Thanks for reporting back 🙂

[enblethen]

Thanks for the update!

[Tinstar]

Well, I guess that fixed it. I drove with my bright headlights on to and from my trip. They didn't blink at all as best I can tell. The dash highbeam indicator would previously flash with the lights but I didn't catch them doing it at all. I guess the new switch was all that was wrong.

[VinCee]

Thanks for checking back in Tinstar. We'll wait to hear back if the new switch cured the problem. Good Luck and enjoy the trip.

[Tinstar]

I replaced the headlight switch. I compared the looks of the switch on the internet and figured out it was a Ford part. O'Reilly's compared the pin configuration from several year models and it is an early 80's Ford switch. The newer switches had different pin alignment.

Anyway the new one works now and maybe I'll find out later this week (first trip since winter) if the lights work without going off and on. If worse comes to worse, I can drive with my dim lights.

I'll report back next week and post the results. Thanks for the help and suggestions.

[I_rv]

go to a nappa store more than likely its a g.m. switch they are all the same except for the reostat for the dash lites look at the resistor coil (looks like a spring in the ceramic disc.)match it up to yours as close as possible it will work fine, by the way to take the shaft out of the switch pull it all the way out(lites on)then push in the little spring loaded button on the side of the switch opposite the the wires then pull out the shaft,to reinstall just push shaft in.

[Tinstar]

I haven't found an ohm's test procedure for the switch so with the small costs, I think I'll just go ahead and replace it and see what happens. At least it was easy to remove.

I'm thinking with a loose ground wire, it would not be so consistent with the on off timing. It acts like what sch911 said with the self setting breaker overheating or something like that.

[VinCee]

Might be a loose or corroded ground wire. Had that happen to my windshield wipers one time.

[ferndaleflyer]

I Googled the number on the switch and it was a Ford part number. Got the new one at Autozone.....Pretty cheap as I remember.....Mine is also a Freightliner chassis.

[Tinstar]

The headlights are not upgraded and are just stock. As far as the chassis goes, it is a Freightliner/Oshkosh.

I looked at the headlight switch and it is quite large, about a 3 inch square box with a half dozen or so wires connected. I wonder where I might find one. The headlights are Ford and several dash controls are also.

[Jagtech]

Certainly sounds like the headlight circuit breaker, which is likely an integral part of the headlight switch. Do you have upgraded headlights that might be drawing excessive current? Otherwise, its just a bad breaker.

[Fla_Tom1]

What chassis do you have ? I had same problem on a freight liner it was a headlight controle modual

[Chiefcpo]

Had that to happen on my older ford van. It was the light switch. Changed it out and never a problem again, (did trade of the van for a new ford.)