headlight problem
Thread Starter
7th Gear
Joined: Nov 2008
Posts: 7
Likes: 0
From: Alvin texas
headlight problem
i have a 79 vette with a 350. i just got it about two weeks ago. it drives great but the headlights didnt work so i can only drive it during the day. they popped up and down, but no light. i replaced the light swith and still no lights but when i replaced it my lights got stuck open. i kno i put the vacuum lines back on right because i labeled everything. i need some help. some vacuum line diagrams and some headlight switch diagrams would b a huge help.
Le Mans Master
Joined: Aug 2006
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Headlight Headache.
Hi and welcome to the forum and Congratulations on your first Vette!
Most electrical problems on a Vette are because of bad grounds. Pull the headlights and with the switch on, use a test light and probe the sockets that plug into the headlight. If you have a good ground on the test light and it lights than you know it a bad ground. If there is no power to the lights than work your way back to the dimmer switch.
The vacuum section:
Remove the vacuum hose on the small side of the check valve and run a jumper hose from that port of the check valve to the "T" on the top port of the relays, with the motor on the headlights should go down.
If they do than either the vacuum section of the switch or the pull down switch is bad.
The correct way to hook up the vacuum line is:
from small port on the check valve, thru the firewall, to the rear connection on the light switch.
Then the next hose goes from the front port on the headlight switch to the bottom port on the pull down switch.
Then the next hose goes from the top port of the pull down switch back thru the firewall and connects with a "T" to the top port of the relay valves. PG.
Most electrical problems on a Vette are because of bad grounds. Pull the headlights and with the switch on, use a test light and probe the sockets that plug into the headlight. If you have a good ground on the test light and it lights than you know it a bad ground. If there is no power to the lights than work your way back to the dimmer switch.
The vacuum section:
Remove the vacuum hose on the small side of the check valve and run a jumper hose from that port of the check valve to the "T" on the top port of the relays, with the motor on the headlights should go down.
If they do than either the vacuum section of the switch or the pull down switch is bad.
The correct way to hook up the vacuum line is:
from small port on the check valve, thru the firewall, to the rear connection on the light switch.
Then the next hose goes from the front port on the headlight switch to the bottom port on the pull down switch.
Then the next hose goes from the top port of the pull down switch back thru the firewall and connects with a "T" to the top port of the relay valves. PG.
Last edited by Peterbuilt; Nov 25, 2008 at 01:07 AM.
Team Owner
Joined: Jun 2000
Posts: 38,923
Likes: 1,482
From: Southbound
Cruise-In II Veteran
Check headlight fuse; check headlight relay
I'm guessing you hooked up the vacuum lines to the light switch backwards. The assembly instruction manual shows the routing. Override switch might also be open.
You can Google this diagram.
...i replaced the light swith and still no lights but when i replaced it my lights got stuck open....
You can Google this diagram.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
79dreamvette...Please follow this diagram to hook up your hoses,dont follow the AIM or the GM shop manual because they are not clear and some are incorrect.
On your headlight switch check the 12 red for power if you dont have power you either have a blown fusible link or the 4 wire connector at the back of the passenger head is not making connection.If you do have power on the 12 red at the switch then check the 14 yellow at the switch with the lights turned on.
On your headlight switch check the 12 red for power if you dont have power you either have a blown fusible link or the 4 wire connector at the back of the passenger head is not making connection.If you do have power on the 12 red at the switch then check the 14 yellow at the switch with the lights turned on.
Last edited by ...Roger...; Nov 25, 2008 at 09:05 AM.
Thread Starter
7th Gear
Joined: Nov 2008
Posts: 7
Likes: 0
From: Alvin texas
you guys rock
yall were a huge help. i got my headlights to up and down again. as far as the lights themself working, thats a different story. but i finally got a good look at the female recieving end up under the dash and i noticed a wire missing and it was melted where the wire was supposed to be. i couldnt find the short so i ordered a new wiring harness from a c3 corvette parts depot. if that doesnt fix it i will definately be runnin back to you guys for some help.
Team Owner
Joined: Jun 2000
Posts: 38,923
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From: Southbound
Cruise-In II Veteran
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
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