Are lights on a timer circuit when engine is not running?

[bfdvollie]

We are noticing a weird problem with the main light switch when the engine is not running. We noticied this before disassembly and it's doing the same thing after re-assembly. We can have the light siwtched set the the 2 o'clock position so all lights are on. If we leave them on and turn on the hazzards after 30-40 min the entire lighting system shuts down. We have to wait about 10 minutes, switch it back to 2 o'clock position and they come back on.

Is there a battery saver timer in the eletrical system or is there an issue with the main light switch? I see the pinpoint checks in the service manual and we'll try them out.

 

[Ferroequinologist]

Nope, I think your breaker in the light switch is faulty, or you have a large draw somewhere. I had the same issue with my first deuce. If I ran the convoy lights and the headlights, everything would trip off after awhile, and I would have to wait and they would come back on.

Does it only do it when the engine isn't running? Mine would do it no matter what.

 

[bikeman]

I've never experienced that on a M998 or M1038 series truck. I've had guys need to get slaved because they left their lights on all day or something.

 

[bfdvollie]

No it did it with the engine running as well as we drove them back from NC. It is better since I cleaned and reset the grounds behind the heater controls that TedG discussed. I've been turning the lights on with high beam with hazards as I was working on installing other components to get a time frame of issue and it got better as I stated above, but still does it. I see the pinpoint tests in the repair manual but not an electrical schematic that I could trace.

Nope, I think your breaker in the light switch is faulty, or you have a large draw somewhere. I had the same issue with my first deuce. If I ran the convoy lights and the headlights, everything would trip off after awhile, and I would have to wait and they would come back on.

Does it only do it when the engine isn't running? Mine would do it no matter what.

 

[TedG]

Nope, I think your breaker in the light switch is faulty, or you have a large draw somewhere. I had the same issue with my first deuce. If I ran the convoy lights and the headlights, everything would trip off after awhile, and I would have to wait and they would come back on.

I believe this is your problem as Ferroequinologist mentioned. Replace the light switch completely with new. Inside of the 3 lever light switch is bi-metallic switch that will interrupt power if too many amps are drawn OR you have a short somewhere. If problem still occurs with new switch, check/replace flasher, bulb wattages, etc. and then clean ALL grounds (including marker light grounds) and install a ground harness kit (or make one). A ground harness kit is a simple harness that connects the control box, the ground on generator, the left rear head ground lug, the fire wall ground and the starter ground ALL together.

 

[bfdvollie]

We borrowed a switch and tested it and we're finding that yes it's the switch. Lights ran for over an hour with no issue. I found a site that shows how to rebuild one, but my Chief says if it's not feasible then go purchase the switch.

 

[Ferroequinologist]

Awesome, I can tell my wife tonight, that I was right for once!

Glad you got it fixed, it is a little nerve wracking to be driving down a two lane in the middle of the night and be plunged into darkness. Helps check for proper brake operation though!