The Stovebolt Site Forums The Shop Area The Electrical Bay Light Issues

Ok, my 55.2 has been on the road for a couple years now. Not a single problem. Well, until the last few months.

I notice at night when driving the headlights fade a bit then brighten back up. It only happens when the truck is warmed up and driven over 20 minutes. It has nothing to do with engine RPM or bumps in the road. The wiring harness is modern. The 70 amp alternator is new, battery new, everything is new. I tugged on the wires to see if there was a short, nada. Maybe the floor dimmer? It seems to work fine.

I'm at a loss. How do you diagnose something like that?

Thanks for any advice.

Michael

does it happen with only low beam, high beam or both? does it affect any other lights, like tail or dash? I'd guess a poor connection somewhere that's oxidized ... check all the plugs in the circuit along the way from power to the lights, including the plugs on the back of the bulbs - could also be something in the alternator that's momentarily dropping the current output, like a sticky regulation circuit

Bill

I only use the high beams because the low beams just don't light up the road enough. Yes, the gauge lights do it too.

I will look through all your suggestions. Any reason why it would happen after warming up for awhile?

Thanks Bill!

something affected by heat - or by the small steady vibration of the engine operation .... sounds like a general light circuit problem, so maybe a main connection on the light switch, like the thermal 'circuit breakers' on the switch, maybe weak springs there, make sure all the plug on connectors are quite tight

Bill

If it seems unrelated to driving, I would suspect your voltage regulator.

Another suspect point may be the thermal contacts in the headlight switch.
don