Headlight fuse

[bblank79]

Hey I have a 1970 Chevy C 10. Im looking for the location of the fuse for the headlights. When i turn them on all of the other lights work excapt for the headlights??? Anyone know anything anout that...

[TBONE1964]

I don't think you have a headlight fuse. I could be wrong. What happens when you turn the brights on? You most likely have a problem with your dimmer switch.

Try turning the brights on and off a couple of times and see what happens. It is a common problem with our trucks.

[bblank79]

T BONE - Thanks for getting back to me. Maybe the reason I cant find the fuse is because there isnt one. When I click the brights on they come on but when i click it again they shut off and then no headlights??? When i repeat this the same thing happems. Also would that be draining my battery???

[TBONE1964]

Do you have a test light? You need to check power at the dimmer switch and see if the dimmer switch has power on the dim side. Make sure the headlight switch is on of course.

If there is no power at the dimmer switch on dim side but on the bright side, then replace the dimmer switch. If it does have power, you will need to look at the wiring from the switch to the headlights. Also make sure the grounds are clean and tight. If the brights work and the rest of the lights work, then your grounds are probably OK.

I am not sure if this would cause you battery to go dead.

[SS Tim]

The headlight switch has a circut breaker built into it. There is no fuse per se. If the high beams are working then work backward from the light connector with a test lamp. If there is power and ground at the connector the bulbs might be the issue.

Suggest you start with a 70 factory service manual electrical schematic in section 12 and not try to use a generic. You can download the 70 manuals here.
http://67-72chevytrucks.com/vboard/s...d.php?t=558016

[da-burb]

Dimmer switch is still the most likely culprit for the headlights. If your horn doesn't work a stuck horn relay is most likely causing your battery drain. I found from multiple experiences that it takes about 2-3 days to drain your battery.

[TBONE1964]

Originally Posted by SS Tim

The headlight switch has a circut breaker built into it. There is no fuse per se. If the high beams are working then work backward from the light connector with a test lamp. If there is power and ground at the connector the bulbs might be the issue.

Suggest you start with a 70 factory service manual electrical schematic in section 12 and not try to use a generic. You can download the 70 manuals here.
http://67-72chevytrucks.com/vboard/s...d.php?t=558016

Tim, Thank you for sharing your knowledge. I was not aware of the circut breaker in the headlight switch. Would this cause an issue only on the dim side?

Also, I attempted to download the chassis manual for a 72 but it keep prompting me to retry. Not sure if there is another way.

I appreciate your knowledge of these trucks. It has helped me a lot.
Tom

[bblank79]

Well thanks for all fo the input! I repalced the dimmer switch and still no headlights. So im going to try to replace the bulbs and see what that brings!!!

[SS Tim]

Originally Posted by TBONE1964

... I was not aware of the circut breaker in the headlight switch. Would this cause an issue only on the dim side?
Also, I attempted to download the chassis manual for a 72 but it keep prompting me to retry...

No, with the breaker it is an all or nothing. The reason I mentioned is to point out there is no specific fuse.
If you are having trouble downloading please post to that PDF manual thread with your specific problem and which manual you are having the problem with.

Originally Posted by bblank79

Well thanks for all fo the input! I repalced the dimmer switch and still no headlights. So im going to try to replace the bulbs and see what that brings!!!

Throwing parts at a problem is a expensive way to fix a vehicle. Diagnosing the problem is the best way to go. Download the manuals and learn the systems, this won't be your only electrical headscratcher.

[bblank79]

I was looking into the possibility of a stuck horn button. I was messing around with the horn and I touched the plate with a screwdriver and it was sparking, is this normal?

[VetteVet]

Originally Posted by bblank79

I was looking into the possibility of a stuck horn button. I was messing around with the horn and I touched the plate with a screwdriver and it was sparking, is this normal?

if the small button inside the insulator under the horn button was touching the plate and you grounded the plate with a screwdriver then you would have gotten a small spark, but the horn should have blown unless you have it disconnected. You should have heard the horn relay clicking if you got a spark since the horn wire is the path to ground for the relay.

check the blue wire that goes to the dimmer switch for power with the headlight switch full on. It is the feed wire for the headlights and the dimmer switch selects the tan or green wire for high or low beams. If you have power on the blue wire then jumper to the green or tan wire and see if either set of lights comes on. If they don't then either the wires are open, the bulbs are blown or the headlight ground is bad. You can also jumper from the positive battery terminal to the bulb terminal to test the bulb if the ground is good. Don't put the jumper on the ground terminal or there will be a large spark.

[Dee72]

Anybody know why my headlights on my 72 c20 Won't work?Ive switched out all the fuses on the fuse panel and even replaced the actually headlights them selves but I cant seem to get them to turn on.Everything else works fine but the headlights or the brights won't turn on,Any help will be appreciated

[harpo231]

dimmer

[Steeveedee]

Probably the headlight switch... but there is a thread here where the service manuals are posted as .pdf files. Get the one for your truck and look over the wiring diagrams to see what color wires you need to tap into, looking for power. After all, it could be a lack of power before the headlight switch. Is it only the headlights that don't work? Like the markers lights, tail lights and park lights and all still work, just not headlights?

[zibs71]

I am wondering if I could ask if anyone knows how to replace a Dimmer switch in my 72 Chev C20. I've tried to find info but can't seem to. I appreciate any help . I'm sure their is a tutorial somewhere for thus. Thank you in advance

Zibs71

[Ol Blue K20]

1. peel back k the mat or carpet to reveal the screws.
2. unplug the plug and unscrew the switch fomt the floor.
3. assemble in reverse order.

[zibs71]

Thank you Ol Blue K20. I appreciate it


Zibs71

[Ol Blue K20]

Originally Posted by zibs71

Thank you Ol Blue K20. I appreciate it


Zibs71

no problem, I'm glad to help

[rockyrivermark]

Instead of buying a bunch of unnecessary parts do some very simple testing. Electrical problems are a process of elimination.
Get a test light which cost $9.
Test for power at the socket.
If power at the socket you have bad ground or bad bulb. U can also check ground at socket by clipping clamp end of tester on socket ground then touch positive side of battery with pointer end. If it lights up ground is good. If u have broke ground and don’t want to track down bad part of ground wire just run a new ground wire.
If no on those.
Check power in and out of dimmer switch.
Check power in and out of the headlight switch. Power in no power out equals bad switch.
Keep working Back to the fuse panel if needed.
Non sense in guessing at a bunch of parts and wasting time and money.

RRM

[rockyrivermark]

Originally Posted by bblank79

Well thanks for all fo the input! I repalced the dimmer switch and still no headlights. So im going to try to replace the bulbs and see what that brings!!!

Stop wasting your money on parts. Diagnostic testing is how true mechanics resolve isssues Changing every possible part is a fools game.

[Getter-Done]

Old Thread revived.

Probably not the Exact issue (but)

Another member has a Possible fix to there issue.

Great answer Ol Blue K20


This is a great Forum













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[zibs71]

I've now bought 2 dimmer switches that are wrong does anyone know the proper Number so I can get right switch. Thank you in advance

Zibs71