Safety issue!!! Headlights turning off while driving!

[slorier]

1999 BLUEBIRD TRANSIT. Electrical issue driving down the highway at night and headlights, possibly taillights turn off for a few seconds and then return. Not flickering like loose connection but going completely off then back on like a switch.
Any help or ideas is much appreciated

[Brad_SwiftFur]

Originally Posted by slorier

1999 BLUEBIRD TRANSIT. Electrical issue driving down the highway at night and headlights, possibly taillights turn off for a few seconds and then return. Not flickering like loose connection but going completely off then back on like a switch.
Any help or ideas is much appreciated

You probably have a self-resetting breaker instead of a fuse; check the headlights for a short, weak or corroded connections (which leads to higher current usage). The headlights *may* have a circuit to themselves or may share it with the running lights.

[family wagon]

Does it happen while standing still also? A self-resetting circuit breaker might cause behavior like this if the load is high or if the breaker is undersized or failing. It would happen equally while standing and while driving.

Is there a pattern -- is it somewhat consistent in being on for x time and off for y time, repeating? That's another indicator of heat-related cause.

Is it related to bumps in the road? A loose connection wouldn't necessarily flicker; it could be a thing that takes a harder jolt to toggle rather than flickering with the lightest little tremor.

You could trace the circuit from the lamps to the switch to the fuse/breaker and connect a test lamp at one or more places along the way to isolate where in the circuit the disconnect occurs. That'll help identify what's failing.

[slorier]

Well I looked over the bus and realized the heated mirror switch was toggled for some reason. Thinking running the heated mirrors in 80 degree weather might have caused overheating and high amperage. Causing the self-reset breaker to trip. Just a theory right now, gotta take it for a test run yet.

[Stu & Filo. T]

I'd start with replacing the headlight switch .

[ol trunt]

All good advice to which I'd add check for loose or corroded grounds as a cause for circuit breaker cycling. Bad grounds cause high amperage draws through breakers causing the breakers to open. Though you might burn a finger, try running the lights for a while and then pinch the ground wire on the headlamps (and mirror). The wire shouldn't be any warmer than the body of the bus. If it is, you have found a high resistance short--just clean up the contacts and you'll be good to go. Jack

[family wagon]

A trick I learned for checking temperature of something that might be hot is to moisten the finger before touching. Lick the finger if you like, but bear in mind lead, road grime, oil, etc when moistening that way.. Anyway, a wet finger touched quickly on a hot surface can better detect the heat without being burned. I don't know why it is -- water improves the heat conduction? It adds some thermal mass so that whatever Btus do transfer don't raise the skin temperature to the burn threshold? Adds thermal capacitance so that the touch can be fast even though the body's processing of "ooh! HOT!" is slow? In any case the method has spared me burning a fingertip several times.