Intermittent headlights

MUFFLERDAVE

MEMBER
1999 CHEVROLET EXPRESS
5.7L
V8
2WD
AUTOMATIC
280,000 MILES

I have this van and intermittently the headlights shut off the rest of the lights or still on running lights tail lights brake lights turn signals they all work, just the high and low beams after approximately thirty seconds to a minute the headlights come back on. Six months ago I replace the headlight switch which appeared to be burned internally and that seemed to fix it, but it is back to doing it again and it occurs more frequently. It would not surprise me to find this new switch getting overheated but I suspect the problem may have something to do with the turn signal switch assembly. I would appreciate any and all suggestions especially ones that work. Thanks

Friday, September 22nd, 2017 AT 6:16 PM

1 Reply

STEVE W.

MECHANIC
15,237 POSTS

Take a look at the grounds on both front lights as well as the bulbs themselves. A poor/failed ground will cause the voltage to seek a new ground path. Many times that will be through the other filament in the bulb. That will not blow the fuses for each lamp but the circuit breaker in the light switch is only rated for 17-18 amps. The extra load will overheat and trip that breaker.

A quick test to see if it is a ground related issue is to pull the fuses for the low beams. That would break the other side of the circuit and either the lights will stop shutting off, if it is just a poor ground connection or if the ground is failed entirely you will shut off one or both headlights.

Now if you have the DRL option it will be different as that uses relays and the switch should not even get warm unless there is a short in the wiring.

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