2000 C3500 dually headlight problem

FNLYFREE

MEMBER
2000 CHEVROLET TRUCK

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.

Monday, November 19th, 2007 AT 8:22 PM

3 Replies

FISHERMAN

MECHANIC
937 POSTS

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!

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Monday, November 19th, 2007 AT 8:44 PM

FNLYFREE

MEMBER
2 POSTS

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.

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Monday, November 19th, 2007 AT 10:14 PM

FISHERMAN

MECHANIC
937 POSTS

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.

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Monday, November 19th, 2007 AT 10:47 PM