69 vacuum lines
Team Owner
Joined: Jun 2000
Posts: 38,923
Likes: 1,482
From: Southbound
Cruise-In II Veteran
Only your time and possibly the cost of some replacement parts if you do it yourself.
All the aftermaket providers carry the parts.
Willcox has schematics.
The AIM shows the factory installation and color codes.
All the aftermaket providers carry the parts.
Willcox has schematics.
The AIM shows the factory installation and color codes.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
There are no repair shops that know how the C3 headlight vacuum system works. They will be "flying blind", just like you are. The system is very simple...but the components are not familiar.
The servo actuators are simple devices that have a rubber diaphragm with vaccum line fittings attached on either side of that diaphragm. Put vacuum on one fitting, the headlights will go UP; put vacuum on the other fitting, the headlights will go DOWN.
The "relays" are the 'decision makers' on what the headlights will be doing. Vacuum should always be going to the middle of the three larger hoses. The small hose going to the upper diaphragm is the 'control' line coming from some switch in the car (ie, headlight switch). When that switch is turned "ON", vacuum is sent to the relay which will move a shuttle valve in its stem so that the [center] vacuum line diverts its vacuum to the "ACTIVATE" outlet. When the signal line does not have vacuum on it, that [center] vacuum outlet is diverted to the "DEACTIVATE" outlet. It's all as simple as that: control switch->to relay->to servo = required action. If you find that vacuum is available at one of the relay lines (yellow is the 'feed' line), you can plumb that line directly to either fitting on a headlight servo bucket to see if it will raise/lower the headlight.
With a working engine (supplying the vacuum signal you need), a vacuum gauge, and a couple of squeeze clamps you can diagnose any problem with your vacuum system. If the engine is not running, then you need a Mighty-Vac to create enough vacuum to test the various components for leakage.
The servo actuators are simple devices that have a rubber diaphragm with vaccum line fittings attached on either side of that diaphragm. Put vacuum on one fitting, the headlights will go UP; put vacuum on the other fitting, the headlights will go DOWN.
The "relays" are the 'decision makers' on what the headlights will be doing. Vacuum should always be going to the middle of the three larger hoses. The small hose going to the upper diaphragm is the 'control' line coming from some switch in the car (ie, headlight switch). When that switch is turned "ON", vacuum is sent to the relay which will move a shuttle valve in its stem so that the [center] vacuum line diverts its vacuum to the "ACTIVATE" outlet. When the signal line does not have vacuum on it, that [center] vacuum outlet is diverted to the "DEACTIVATE" outlet. It's all as simple as that: control switch->to relay->to servo = required action. If you find that vacuum is available at one of the relay lines (yellow is the 'feed' line), you can plumb that line directly to either fitting on a headlight servo bucket to see if it will raise/lower the headlight.
With a working engine (supplying the vacuum signal you need), a vacuum gauge, and a couple of squeeze clamps you can diagnose any problem with your vacuum system. If the engine is not running, then you need a Mighty-Vac to create enough vacuum to test the various components for leakage.
Thread Starter
Tech Contributor
Joined: Sep 2011
Posts: 109
Likes: 2
From: In the booth Maryland
Thank YOU 7T1, I worked on Camaro RS vacuum headlights years ago, but the vette system is way more complicated. I ordered a troubleshoot guide with my lines but it was out of stock. Your organized details on the relays are just what I needed, thanks sooo much for taking the time to share your knowlage.
G
G
Safety Car
Joined: Oct 2007
Posts: 3,729
Likes: 267
From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
start with a new hose kit, that fixes most of the leaks.
replace 1 hose at a time. they are color coded, easy to do.
then check each componet as you are attaching the new hoses.
study and learn what each componet should do, when it works correctly.
replace 1 hose at a time. they are color coded, easy to do.
then check each componet as you are attaching the new hoses.
study and learn what each componet should do, when it works correctly.
