No Headlights No Ground ?

[54blackhornet]

Been trying to diagnose why I have no headlights, both low and high beams. I replaced the dimmer switch with one from GMC Paul’s. Have power on the blue wire at terminal on dimmer. Checked for power at headlight terminals, nothing. If I hook up a test light between battery + and headlight terminals - ground I get nothing. Funny if I do same test with the main power wire disconnected from battery I see ground at headlight terminals ? I checked and cleaned the main ground screw near the regulator. All other lights, side markers, turn signals work fine. How can you loose the headlight ground separately from the others ? Headlight switch bad ?...thanks I am confused...

[56chevnick]

I had something similar happen to me. My foot dimmer switch wasn’t grounded so I sanded a little paint off floor, under the switch, power was going through after that. Maybe a fluke but it worked for me.

[BigBird05]

Power goes from the dimmer switch (tan wire ) thru the bulk head connector to the head light. Do you have 12+ on the tan wire at the head light connector? If yes do you have 12+ on the black wire at the head light connector. If yes run a ground wire from the battery - to the black wire on the head light connector. The head light should work. If the head light works you have lost your ground to the chassis. If you don't have power on the tan wire at the head light check the bulk head connector for either corrosion or if it's loose.

[Wrenchbender Ret]

Check the connector at the dimmer switch. The terms. often get corroded. A replacement pigtail is available. The dimmer switch does not have to be grounded. If you have current at the dimmer switch the light switch is ok as far as the light switch is concerned.
George

[54blackhornet]

I have power at the blue wire at dimmer, I tested the new dimmer and it’s good. I only see one ground for the headlight terminals going to main ground screw on crossmember by regulator. I will test for 12V at tan wire out of dimmer next l along with 12V at headlight terminals. thanks guys .

[54blackhornet]

SUCCESS ! I determined that I had power going to the dimmer, out of dimmer to the brown (low beams) but still nothing at the headlight terminals ? Went back to the core support ground screw. Removed it, took sandpaper and cleaned up the metal, installed another new star washer, tightened it up. Ran another ground cable from - negative battery cable to bolt on core support with new star washer. Pulled the switch and presto HEADLIGHTS ! During all this I inspected all connections at dimmer switch & Headlight terminals. All where corroded. Cleaned them all as well as possible and applied dialectic grease. So new dimmer, new headlights and a lot of long overdue maintenance produced a smile...thanks everyone for your help..Jack

[firedemon]

now that you have done all that try the relay system it will take a lot of stress off all that old wiring headlight switch and foot switch plus brighter headlights

[mr48chev]

Unless the truck has halogens with a high draw like those that use H-4 bulbs with higher wattage high and low beam I'd say that his main problem all along is corrosion on the truck. That may be due to what happened to it in a previous life before Wrenchbender ret acquired it. Or like my 71 sitting too long waiting it's turn in the work space.

[firedemon]

i would say your right . the relays will relieve some of the stress on the corrosion that is likely still hidden plus give a much better light but its only something to think about they are working now after all and some prefer the factory setup

[54blackhornet]

This pickup was stored inside for two decades before I received it. It’s pretty original. The wiring down by the dimmer switch connector had some significant corrosion as did the headlight terminals. I believe it’s from sitting outside. I only use it to bring in firewood from my wood lot, afterwards I pull the battery and it sits till springtime. I actually enjoy tracking down the no headlight situation. Learned a lot tracing the no ground . I would consider upgrading to relays but just don’t use it at night much....

[firedemon]

ya probably not worth the effort