Blinking headlights and gauges

[evotech]

I have a problem where some the gauges and headlights blink on and off while driving. The connections at the battery are good. This is a 1998 HR Endeavor DP. I know it sounds like a ground problem, but I would not even know where to start chasing it down. Any help would be appreciated.

[mahon1993]

Could very well be a ground problem. What do you mean the gauges blink on and off, the lights in them or are the needles moving around?
Greg

[RustyJC]

For obvious safety reasons, the headlight circuit (which often also powers the instrument lights) is normally not fused but rather is protected by an automatic reset circuit breaker. If this breaker is tripping and resetting, it could be because the breaker has gotten weak, or it could be because of a high current draw through the light circuit.

Rusty

[bigskymt]

As RustyJC said they rarely use fuses and mostly circuit breakers in headlamp circuits. Depending on the chassis its very possible its a relay that applies power to the lamps. You might be able to hear the relay activate when you turn on the lamps, then its a matter of checking voltage at the coil. Its also possible a relay that supplies power to certain dash functions is failing.

[evotech]

Quote:

Originally Posted by RustyJC For obvious safety reasons, the headlight circuit (which often also powers the instrument lights) is normally not fused but rather is protected by an automatic reset circuit breaker. If this breaker is tripping and resetting, it could be because the breaker has gotten weak, or it could be because of a high current draw through the light circuit. Rusty

Would there be both a relay and a circuit breaker? I found the relay. It clicks when I switch on the lights, but sounds weak if that is possible. Funny thing is that the headlights stay on even if the relay is removed.

[mahon1993]

You said the lights blink while driving. Are they OK when you are not moving? If so, you might have a loose connection somewhere. While the lights are on try moving wires and things around to see if you can gt them to blink.
Greg

[evotech]

Quote:

Originally Posted by mahon1993 You said the lights blink while driving. Are they OK when you are not moving? If so, you might have a loose connection somewhere. While the lights are on try moving wires and things around to see if you can gt them to blink. Greg

I can't replicate it not moving, I have pulled and tuged on the wires that I can find for the headlight circuit to no avail. I would hate to send it to freighliner for this, but it may come down to this.

[mahon1993]

Is it just the headlights or all the exterior lights that blink? A good place to start would be the headlight switch. I have seen them fail on even newer MH's. The contacts get worn and the wire connections to them can fail. You should be able to remove the switch from the dash to inspect it. Or at least crawl under there to look at it. Look for loose wires and evidence of overheating.
Greg

[evotech]

Quote:

Originally Posted by mahon1993 Is it just the headlights or all the exterior lights that blink? A good place to start would be the headlight switch. I have seen them fail on even newer MH's. The contacts get worn and the wire connections to them can fail. You should be able to remove the switch from the dash to inspect it. Or at least crawl under there to look at it. Look for loose wires and evidence of overheating. Greg

Sounds like a good idea. I will give it a look today. What I am really curious about is if/where there is a circuit breaker for the headlamps. When this problem happens it seems like it could be a circuit breaker since it always comes back in a few seconds as if a circuit breaker was resetting.

[mahon1993]

Are your lights blinking on and off, or is it more of a flickering. Circuit breaker problems would make the lights turn on and off kind of like a turn signal but a a much slower rate. Flickering while moving indicates a bad connection.
If your problem is with the headlight switch it is probably a General Motors part you could get at an auto parts store.
Greg

[bigskymt]

Evotech: I checked my '04 Freightliner and found several circuit breakers in a chassis electrical panel above the Onan. 2 were marked as lighting, dash etc.
When I turn on my light switch I hear a relay that comes on with parking lights, no change when I turn on headlights.
My fuse legend shows one relay for lighting and another for hi-beams.
I agree with your diagnosis of a circuit breaker resetting.
You might try following someone as they observe your headlights, if one side dims (as light or wires shorting to ground before complete failure) you'll have someplace to start. You never mentioned if the clearance lights/tailights quit too.

[evotech]

Thanks for all of the help guys. Today I called freightliner. They immediately diagnosed it as a bad headlight switch. They said that they had a lot of problems with them. $25 later and a trip to the auto parts store and I am back in business. Now onto the problem of the stuck pac brake. It never ends