2000 C3500 dually headlight problem

[quote:e42c324c7e="fnlyfree"]I have a 2000 c3500 with a 7.4 liter and auto trans. It has about 159000 miles on it. The other day I noticed that my low beam headlights were not working. I turned on the high beams and they came right on. I switched back to low and still nothing. I have day time running lights (low beam headlights) that are working fine. If I turn the switch to off or parking lamps, the day time (low beam) lights are on. When I turn the switch to on, the low beams go off. The high beams will still work though. I tried changing the switch and that did not help. I bought a new headlight relay but, I can't find where it is on the truck to replace it. It is not in the relay/fuse box under the hood.(left of the steering column) It is not on the block under the dash either. Where could I find the headlight relay and do you think that it may be causing my poblem? Thank you.[/quote:e42c324c7e]

Hello !!

well start checking fuse # 9 and #15 there is two fuses that feed the low beam headlights I was checking the schematic...
also there is no relay for the headlights..

the headlights are controlled by the convenience center (under left side of dash)

if you want I`ll send the complete schematic to your e-mail

but check those fuses first and let us know!

good Luck!

[quote:e01ff5e7f2="fisherman"][quote:e01ff5e7f2="fnlyfree"]I have a 2000 c3500 with a 7.4 liter and auto trans. It has about 159000 miles on it. The other day I noticed that my low beam headlights were not working. I turned on the high beams and they came right on. I switched back to low and still nothing. I have day time running lights (low beam headlights) that are working fine. If I turn the switch to off or parking lamps, the day time (low beam) lights are on. When I turn the switch to on, the low beams go off. The high beams will still work though. I tried changing the switch and that did not help. I bought a new headlight relay but, I can't find where it is on the truck to replace it. It is not in the relay/fuse box under the hood.(left of the steering column) It is not on the block under the dash either. Where could I find the headlight relay and do you think that it may be causing my poblem? Thank you.[/quote:e01ff5e7f2]

Hello !!

well start checking fuse # 9 and #15 there is two fuses that feed the low beam headlights I was checking the schematic...
also there is no relay for the headlights..

the headlights are controlled by the convenience center (under left side of dash)

if you want I`ll send the complete schematic to your e-mail

but check those fuses first and let us know!

good Luck![/quote:e01ff5e7f2]


I checked the fuses. They are not blown. I was able to get the low beams to stay on a little while ago. I was searching for any obvious problems and I started switching from low to high beam on the dimmer switch and also changing from parking lamps to the on position. The low beams started to come on and I was able to move both the headlight switch and dimmer switch to different positions and still the lights worked as they should. I turned everything off, waited a while and tried again. The low beams would not work again. I am really confused now.

Thank you for your help.

Hello Rodney..

well those solid state controls are hard to diagnose (convenience center control) ..
I will send you an schematic to your E-Mail that way you can check the headlight wiring..

good Luck and we`ll be here to continue ..