01 Pete 379 no headlights (2024)

As said above, 01 Peter 379. Pre trip turned up no headlights. Clearance and blinkers all good. When I play with the dimmer switch I get NO indicator for high beams. Moved some relays around no change, fuses good. Wiring on headlight switch is tight as is dimmer switch. I think I have a power supply problem.

Help me here please.

Any chance you can borrow a signal-stat to rule that out. Only other thing I know is start chasing wires.

Theres a relay under the dash on the left side of the steering column. Kinda hard to get to but that is probably your problem. I cant remember exactly how I got to it but I think you have to take the end dash panel at the left door off to get in there? It or the speedometer panel but I think its the end panel. It will be bolted down if I remember correctly? I had a 2000. You just about have to have 3 hands to take it off- 1 to hold the light in there, and 2 to hold the relay/switch and take the bolts out.

Thanks guys, I had to take a different truck but will be back to mine in a couple hrs. I'll do some more poking around. Thanks for the tips and anyone else keep them coming

Sure thing. Just shine your light down in towards the steering column and youll probably see it down in there. It will have a pigtail plugged to it and mine was square if I remember right- been a while. Mine was doing the same thing yours is. I replaced fuses, light switches and all kinds of stuff and another driver happened along and told me about that. I replaced it and my headlights went back to work. Petes also have right and left headlight breakers (white and round) in the fuse box. I also pressed them to reset them and it did no good.

B4 rippin into dashboard....push your blink switch up....day position....if they come in a/the blink switch....then it's almost certainly the headlight switch itself....if not probably the pita to get to relay behind steering column

Well I didn't think it would be in the headlight switch because the clearance lights still came on with that switch. So checked everything else first and found nothing. Guess what, it's was the switch, one pole was melted a bit as is the plug that it plugs into. So a new switch and I'm off and running. Not sure what to do about the slightly melted plug. I don't see any connectors to replace it. Might just have to splice in a new one

Thanks guys

Yea I used to keep a couple of headlight switches with me in mine. Id pull some pretty ragged company trailers and sometimes theyd have shorts in the lights and melt those posts on the switches. They wasnt that expensive when I had mine, course that was several years ago. You can get one of those plugs at Peterbuilt but as long as that one is working, Id run with it. If it got too bad melted, and I wasnt close to a Pete dealer, Id cut the plug off of it and just go buy a pack of female connectors and replace all four wires with them and plug them back up(just make sure you watch where each wire goes). That was always a last resort though. Its best to just get another plug. Glad you figured it out. Be safe.