Headlights are dim or don't come on

[custom10nut]

I hope somebody can help me. I bought a set of halogen headlights for my 70, but when I pulled the switch, they wouldn't come on. Checked the connections, and played with the dimmer switch, and I got them to come on, but only on low beam, and they're very dim. I thinking either it's the switch, or the connections under the dash. The markers are doing goofy things too, so I think it may be the humidity that corroded the connections.

[ray_mcavoy]

Yes, it sounds like you are on the right track with checking the switches (both headlight & dimmer switch) as well as checking the wiring for corroded connections. Also check the condition of the headlight ground wires that attach to the radiator support and the battery to front sheetmetal ground wire.

[custom10nut]

Great. Thanks for the info. I guess I'll be chasing wires tomorrow.

[Mmorgan32]

Check the connector to your dimmer switch. I had that problem and It ended up being just to connector. Bought a new one at the auto parts store and spliced it in

[custom10nut]

Got em fixed. I ended up pulling all the connectors, and spraying them with contact cleaner. Also I put in a new switch on the dash. Everything I did has needed it of a long time, so now it's done. I'm lovin the new Halogen lights BTW I picked them up for a real good price at the Auto Fair

[firedemon]

you should look into the headlight relay harness upgrade takes a lot of stress off the circuit and switches and really does brighten up the lights best mod I have done so far .

[custom10nut]

First I've heard of this upgrade. Of course I'm a bit behind the latest mods. Where do I get one of these harnesses, and how difficult is it to put in? One reason I ask, is that I'm going to be buying a new complete wiring harness, and I don't want to have to cut up a new harness like that

[firedemon]

I got mine on e bay but most of the parts suppliers for our trucks have them the one I got just plugs into the factory headlight plug to switch the relays and pulls main power from battery and grounds to factory headlight ground on the support took all of 20 min to hook up

[Stocker]

If you're comfortable working with wiring, you can buy a couple relays and build your own harness. You'll also need wire of course, rosin core solder, a bit of heat shrink, and maybe a few feet of wiring loom to keep it all tidy..

[VetteVet]

Here''s a diagram to wire up the relays and the lights.




Start with the tan and light green wires to the left headlight from the harness.
Cut them back about 6 inches. then connect them to the relays. On terminals 86.
The tan wire is the low beam relay wire from the dimmer switch, and the light green wire is the high beam relay control wire from the dimmer switch.

Ground both terminal 85s on the relays. This completes the control circuit for the relays. the diagram shows the grounds on 86 but 85 is used on most applications. either way will work but some relays have diodes in them to prevent inductive discharge when the relay is shut off.

run your power wire from any hot source with a 30- amp fuse inline.
connect this wire(s) to terminal 30 on the relays.

Now run a wire from terminal 87 on each relay back to it's respective wire on the left headlight and you're done.

[racerop]

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