Help with headlights

[bull1966]

Fellas,

I have a 64 chevy c10 that I have completely rebuilt to include a complete (original style) under dash harness, engine harness, and a heavy duty headlight harness.

I have everything hooked up, ground wires in place at each headlight, HD harness plugged into original head light harness, and a new dimmer switch/head light switch.

The headlights work fine on low beam, but when I click the dimmer switch for high beam, they stop working. Dash lights, tail lights,...etc work fine......Any ideas??

[markeb01]

What do you mean by “they stop working”? When you go to high beams do the low beams go out, or do the high beams fail to illuminate?

If the low beams are going off, it sounds like high beam bulbs could be installed in the low beam locations. There should be three wires going to the low beam bulbs and two wires to the high beam. The low beam lamps actually have two filaments, a high filament (for normal low beams), and a dim filament which illuminate as marker lights when switching to high beams. On high beams, the high beam bulbs actually produce all of the usable light. There is an adapter available which keeps the high power filament in the low beams on all the time (both on low beams and high beams).

Perhaps the attached diagram and links will help explain:

67-72chevytrucks.com/vboard/showthread.php?t=387693&highlight=headlight+relay

[bull1966]

They go completely out. Both the low beams and high beams go out.

When I click back to the low beams, the low beams come on and work fine. I click to high beams, and that's when both the low and high beams go out.

Everything looks right, based on all the diagrams I've seen and what you provided me as well....Scratching my head now....

[bull1966]

Update: Got her fixed up! Turns out, I had loose connection somewhere in the "new" dimmer switch.

To troubleshoot, I swaped the new one with the old one, both the high and low beams work as advertised.