Headlights stopped working overnight

[El Campo]

72 c10 was parked for years and then just now started to drive it. Last night the headlights worked perfectly but then this morning neither hi or low works. Ideas?
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[HO455]

I would suggest inspecting the hi/ low floor switch and the wiring to it first. It is fairly easy to access and a common problem area due to moisture. Then the light switch can be checked. First check for 12v between the switch and ground. If you don't have a wiring diagram just do a search above. And this link should help.

http://67-72chevytrucks.com/vboard/s....php?p=6822383

Good luck.

[NGN]

May be crazy, but it has happen, did both lamps happen to burn out.

[KevinK7]

Just to comment. I've been going through my '68, headlights 'were' working fine, ..then midstream, parking lights OK, but headlights no go. Since I had it all apart, I ordered a new H/L switch, ...and that was it. It just went.

[67C10Step]

I remember driving my 70 model as a teenager and when I dimmed the lights once they both went out completely! A flurry of quick left foot clicks got the low beams back on and I drove home without switching again.

Replaced the high/low switch and fixed the problem.

[zosoppp]

Originally Posted by KevinK7

Just to comment. I've been going through my '68, headlights 'were' working fine, ..then midstream, parking lights OK, but headlights no go. Since I had it all apart, I ordered a new H/L switch, ...and that was it. It just went.

The headlight switches contain a auto-resetting breaker in the headlight circuit, and that might be what finally went. It's the only protection in the factory headlight circuit (other than the main fusible link).

The parking light, dome light, indicator dimmer functions of the switch do not use the internal circuit breaker.

[KevinK7]

Originally Posted by zosoppp

The headlight switches contain a auto-resetting breaker in the headlight circuit, and that might be what finally went. It's the only protection in the factory headlight circuit (other than the main fusible link).

The parking light, dome light, indicator dimmer functions of the switch do not use the internal circuit breaker.

Interesting, never knew that.
If it's indeed "auto resetting", it definitely went since I tried it over the course of a couple days before I put the new one in.

Thanks for the info...

[zosoppp]

Originally Posted by KevinK7

Interesting, never knew that.
If it's indeed "auto resetting", it definitely went since I tried it over the course of a couple days before I put the new one in.

Thanks for the info...

My understanding of the auto-resetting feature is that if it pops it resets almost instantly. Imaging having to wait many seconds on a dark road for the headlights to come back on after something happened. That's likely why they didn't use fuses to begin with on the headlights (that and the higher current requirements perhaps).

[rockyrivermark]

Simple testing will tell you where the prob is rather than throwing parts at it.
Get a 12v tester. Cheap and useful
Make sure you have a good ground on tester
Turn lights on and test for power at the headlight plug.
If u have power check grounds.
If not just work backwards to dimmer switch in and out
Headlight switch in and out etc.

https://www.harborfreight.com/6-12-v...iABEgLHm_D_BwE

[El Campo]

Found the problem. Iv heard of some weird stuff happening before but none beat this! Switches all checked out fine. Initially just the high or lows (can’t remember which) both stopped working at virtually the same time. Then about two days later both of the highs stopped working. Would you believe it that both headlights were burned out in both circuits???? I cleaned the connectors and did everything possible and they were both smoked. Changed over the two different headlights that I had on the shelf and everything worked perfectly first time
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[davischevy]

Well I am glad you found the problem.

Those symptoms are usually caused by the dimmer switch.

[HO455]

Originally Posted by El Campo

Found the problem. Iv heard of some weird stuff happening before but none beat this! Switches all checked out fine. Initially just the high or lows (can’t remember which) both stopped working at virtually the same time. Then about two days later both of the highs stopped working. Would you believe it that both headlights were burned out in both circuits???? I cleaned the connectors and did everything possible and they were both smoked. Changed over the two different headlights that I had on the shelf and everything worked perfectly first time
Posted via Mobile Device

Not to raise undue alarm, but I would do some checking of the charging system. A voltage spike could have blown your head lights. Are there any other bulbs out?