headlight problems

[harv]

Ok, i posted before, but i seem to have lost it. I have a 69 chevy i have parking lights working all around and brake/tail lights, even back up lights but my headlights wont come on. The switch is working, i tested and have voltage coming out when i pull on the switch, i just dont have power at the lights. there is a large multi plug on the firewall i took it off and tried cleaning those contacs a bit, im not even sure if the headlight power goes through that though. it there a headlight relay? where would i find this? its been 20 yrs or so since i worked on an old 69 like this so I am re-learning.
Any help would be seriously appreciated!

[dnorris009]

Do you have brights?
Replaced both headlights & the dimmer switch on my 70 C-10.
But it just wasn't getting good contacts at the headlight.
Wiggled the plugs a bit & they came on.

Check this thread out....
http://67-72chevytrucks.com/vboard/s...ghlight=dimmer

[harv]

no I have nothing, I checked the plugs at the bulbs and i am not getting power. I am wondering if there is a relay for the lights or is this year before they added those?

[Stocker]

These trucks didn't come from the factory with a headlight relay, but it is a popular mod to get full voltage to the headlamps. With no voltage at your lamps, I'd suspect either the headlamp switch or the dimmer switch is bad.


Edit: I just re-read where you said the headlight switch is good. Try the dimmer switch next....

[harv]

the dimmer switch will cause no power to the lamps? interesting, dont know where i would find a wiring diagram do you?

[Stocker]

No, sorry.... maybe someone will chime in. It's been many years since I replaced my dimmer switch -- I think power goes from the headlight switch on the dash to the dimmer switch, then to the headlamps.

[harv]

well if thats the case then i can just wire around it till i get a new switch, i have been stuck not able to ride at night... yeah if anyone else knows where i can get a wiring diagram...?

[Stocker]

I know you said there's no power to the lamps, but...... have you checked the ground at the lamps?

[harv]

ummm, not sure, how do i do that?

[Stocker]

Connect a test light (or voltmeter) to a known voltage source, then check each headlight connector. One of the three prongs will always be grounded. I can check mine to see which of the three is the ground.

[harv]

oh yeah ok, that would be the easiest! Sorry, i went to work in computers now its hard to think about the simple stuff! My dad would have smacked me in the head right there! lol!

[Stocker]

If you unplug a headlamp and are facing the connector, the prong on your right is the ground.

[harv]

awesome! Thanks Stocker!! I will check that as soon as I get home! So if the ground is bad i should be able to just pick up a ground off the body or frame some where? or do I need to go back to the source?

[Stocker]

I'm not 100% sure but I think the ground comes from the core support, so it must be properly grounded for the headlamps to work. I did the relay mod to mine so it's a bit different....

[harv]

is that relay modification a big deal to do? I seen the parts for sale online.

[Stocker]

Not bad... having just a bit of basic electrical knowledge helps, but it's not hard to do, just takes a little time. It's well worth the effort with stock headlamps and virtually a must-do if you upgrade your headlamps.

[harv]

Very Cool! Thanks for all your help today. Hopefully i will have headlights tomorrow! Then One more hurdle, i believe I have a bad wiper motor, luckily it doesnt rain too much here along the coast!
I will let you know how the headlights go! Thanks again!

[El Jay]

Originally Posted by harv

well if thats the case then i can just wire around it till i get a new switch, i have been stuck not able to ride at night... yeah if anyone else knows where i can get a wiring diagram...?

I hope this helps you.
If you need any other diagrams, just holler.

I would definitely check the dimmer switch.

[harv]

Thanks El Jay!! Gonna print this one off!

[harv]

El jay is there a place i can download that diagram? it is not coming out clear by capturing it from here.

[cdowns]

a factory service manual at very cheap price from most board vendors has full size wiring diagrams and a whole lot more great info for that one low price


dimmer switches available at any autoparts store are cheap around $5

[harv]

ok, Sounds good! Thanks again!

[mrein3]

On this vehicle, if the headlight switch is ok, it is usually the connector on the dimmer, not the dimmer switch itself.

You said your headlight switch is good. Knowing that, high beam or low beam, 12V is sent to the dimmer switch. Depending on the position of the dimmer switch you get that 12V to either the high or the low beam circuit.

Use a test light or DMM to verify 12V at one of the wires on the dimmer connector. If you got 12V there, just use a jumper wire and cross that wire to one of the other two. One of the other two is high, the other is low.

If you got 12V there, look at the connections. If they are all green and furry, change the wire ends. You can push each "pin" out of the conntector, clip it a touch shorter, and put on a new end. (NAPA part number 725147).

THEN after you get your lights working, do put in the "relay upgrade". This will greatly extend the life of your headlight switch and give you much better light out of the headlights. By the time that 12V gets to the headlight from the switch to the dimmer to the headlights, you're sitting at 10.5 - 11 volts. After the relay upgrade your voltage drop will be next to nothing and you'll be wondering why you didn't run your headlights off of relays since the day you bought the truck.

[harv]

Ok, thats sounds great!! Thanks so much!! I might be able to take her for a drive tonight! (as long as it dont rain)

[El Jay]

Originally Posted by harv

El jay is there a place i can download that diagram? it is not coming out clear by capturing it from here.

I don't remember where I found the wiring diagrams.
You may be able to copy & paste to Word & then expand the diagram(s) to full size.

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