Intermittent headlight/dash lights

[Digitallando]

Hello, after an hour or so of driving the headlights and dash turn off for 10-15 seconds. Then they turn back on again for a few minutes then go out for 10-15 seconds, and the pattern continues until the drive is done. Sometimes it's a one time thing without repeating. I've replaced the headlight and multi-function switches which seems to make the intermittency less so. I've cleaned a few of the grounds and will clean the rest. Could pretty much any of the grounds be causing this problem? What other causes may there be? Thank you

 

[Orpedcrow]

I believe these have “self-resetting” circuit breakers which would explain the cycling. (Looks like a metal fuse) A bad ground could cause increased resistance, which turns into a higher draw on the system possibly tripping the breaker.

Could also be a weak breaker (they are getting pretty old lol) and it just can’t handle the load anymore.

What year truck?

 

[Orpedcrow]

While you’re cleaning grounds, check the front harness real good, especially around corners and anywhere it passes through the core support for any damage. Could be a tiny wear spot or pinch somewhere grounding out.

 

[Digitallando]

While you’re cleaning grounds, check the front harness real good, especially around corners and anywhere it passes through the core support for any damage. Could be a tiny wear spot or pinch somewhere grounding out.

1998 k2500 Silverado. Isn't the breaker in the headlight switch that I replaced? Is there another one?

 

[Orpedcrow]

My mistake, I thought the breakers in the fuse box were for the lighting system. They’re for power windows and accessories.

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[AK49BWL]

Yeah the circuit breaker for the headlights is inside the headlight switch, on every GMT400, not just the old or new ones... Possible you got a DOA, but it's worth looking into the grounds for the headlights first, or a possible break in wiring insulation allowing moisture into the wire that can short to a ground point.

 

[Schurkey]

Almost certainly not a typical "ground" problem where the wires or connections corrode. Corroded connections REDUCE current flow, that'd be the last thing that trips a circuit breaker.

You've got excess current flow, and it's tripping the self-resetting circuit breaker in the light switch.

1. What is system voltage? If that alternator is putting out 16+ volts, you might have this sort of issue. It's really hard on pretty-much everything electric/electronic in the truck.

2 Bare spots on the wiring to the headlights? They touch ground, current flow increases, and the breakers pop--then reset as they cool down.

3. I can imagine some sort of unusual fault within one of the headlights. Verify that all the headlights work and are of reasonable brightness.

4. The "headlight" switch also controls running lights. I don't know if those are tied-into the circuit breakers, though.

5. I'd expect TWO circuit breakers--one for low-beams, one for high beams. Do you have problems with the circuit breaker popping when you use high beam lights? or only with low-beams?

 

[Orpedcrow]

Almost certainly not a typical "ground" problem where the wires or connections corrode. Corroded connections REDUCE current flow, that'd be the last thing that trips a circuit breaker.

I was thinking about a loose ground rattling around, off and on, getting hot, and now that I’m typing this out I remember these trucks like to melt bulb sockets.

A melted socket rattling around, making and breaking connection will definitely get hot. Plus the (carbon?) build up of the connection sparking creating more resistance.

 

[AK49BWL]

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4. The "headlight" switch also controls running lights. I don't know if those are tied-into the circuit breakers, though.

5. I'd expect TWO circuit breakers--one for low-beams, one for high beams. Do you have problems with the circuit breaker popping when you use high beam lights? or only with low-beams?

To answer these two for you: the circuit breaker in the switch only has the headlights on it, and there is only one. From the headlight switch the circuit goes to the brights selector switch, then to the lights - so unless someone hacked in a quad beam mod using the factory wiring, the circuit breaker will only ever run low OR high beams.

 

[GoToGuy]

When this happens you lose headlights, instrument cluster lights, what about tail lights and side marker lights? There all controlled by headlight switch. It's the only thing all three have in common.