No Headlights!!

[popcop]

Hi, I'm new to the site. This is my first posting. I just got a 64 C-10, the problem is it has no headlights. I have power to the green wire, but the blue wire shows no power. P/O advised the switch wasn't very old. Could it b a possible dimmer switch? Not good with electrical stuff, so any and all help will be appreciated. I'm sure you will hear from me again. Thanks,
Popcop

[markeb01]

The dimmer switch would be a good guess, it is one of the more common electrical problems on trucks this old. The proximity to dirt and water from years of wet/muddy shoes takes a toll.

It doesn't sound like a blown fuse if you have power at the lamps. I'm not familiar with the green wire/blue wire, perhaps the blue wire isn't hot until the high beams are switched on, and if the dimmer is bad...

Next up is just a plain old bad ground. New paint and rust are just about as bad as each other for canceling the ground. I'm a believer in overkill in the ground department. I have 14 awg black wire attached to each lamp bucket, running to a common connection, which in turn runs to a ground on the frame near the battery. The primary negative battery cable goes to the engine block, and another ground cable goes from the block to the frame, and all the other grounds connect here (including one to the body).

First check and make sure your bulbs are good. Next, apply a small amount of dielectric grease to the terminals and the sockets to make sure the juice isn't stopping there. After that it's checking wires. Good luck.

[popcop]

Thanks, upon further checking, I have power to dimmer and when I work dimmer off and on it turns power off and on in the blue wire. The green and blue wires are what goes to my headlights. My headlights still don't work and dome light just quit. I had the dome light working, I don't know about the headlights?? Bought without checking, getting forgetful.
popcop

[Woogeroo]

on my '65 c10:

I had issues first with the dimmer switch on the floor... it would read good, but would suddenly stop working when it wanted to.

Another issue I had was my headlight switch stopped working, I took it apart and cleaned it, put it all back together... but it was never reliable again, so I swapped it out.

[Vernski]

Hey Popcop try this web site- 6066gmcguy.org go to the lighting & electrical section it will get you straightened out. Most problems are 90% bad ground problems although dimmers will do funny things as mine did as well.---Vernski

[joe231]

you just need to trace the power from the switch out, and wiggle all the connectors (with the lights on) that I mention later...I have a diagram at home I will post tonight. you have 3 wires at your dimmer, a hot from the headlight switch and a high and low beam wire. If you are getting power through the dimmer, next in line is the firewall connector, check for @12vdc there, if that is good, the next in line is the connector on the radiator support in close vicinity to the horn relay (our truck sat for some time and there was corrosion in the connector), if you have @12vdc through it then you need to check at the headlights, lots of times there will be corrosion built up in the headlight plug. If you have @12vdc through all of those connectors, check the headlights themselves.....do you have a multi-meter? If so you can check continuity on the lights by setting your meter on ohms, one lead on the ground spade and the other on the high spade then on the low spade.....you should have something there (not sure of the exact number). if it shows OL or infinity (sideways 8) then the filament is probably broken, if the lights check good then you will need to check the grounds.

hope that doesn't sound like I am rambling....

[joe231]

here is a diagram








blue is your hot from the switch
tan and light green are the wires from the dimmer to the lights, the harness connector is on the fire wall
the baffle connector is on the radiator support
and each light has a ground

if you have questions or need more help just hollar

[popcop]

Thanks alot guys, I will in the next few days see what I can get figured out. As far as a tan wire, I don't remember a tan wire. Mine is blue and green, I believe. I will check again. Will keep you posted, thanks again,

popcop

[1964C10]

I had similar issues with mine and one thing I did was take the connector apart at the firewall and then CAREFULLY used a hot wire temporarly clipped onto the positive battery terminal and hit each connector terminal going to the headlights to see if they would light up, that will help you to start separating problem areas. For me it was a combination of all the things mentioned above, bad ground, bad bulb, bad headlight switch (it ended up melting) and wiring that the PO for some reason started trying to splice into midway in the engine compartment.

[popcop]

Thanks, going out later today to see if I can get them lit.
Thanks

[popcop]

I have lights!!! Bad wires about 6 in above dimmer switch. Fixed those an Waaaalaa. Thanks for all the help guys, hope I can pay you back some day.
Popcop

[1964C10]

Glad it worked for you. Remember all the juice for the headlights goes through the switch so make sure all the wiring is good. On mine it caused my switch to literally melt and start smoking before they died.