headlight problems ect...
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Burning Brakes
Joined: Apr 2000
Posts: 1,076
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From: Dixie TN
headlight problems ect...
I bought a 79 Corvette after my 78 was totaled. The headlights won't come up. I have repaced a seal and boot on the 78, but thats about it. I bought a vacumn tester and have a trouble shooting pamplet. Any information or links would be helpfull. Also the lights only work on high beam. Where do I start trying to find this problem? I would like to pull the entire headlight assembly from my 78 any help or links on doing this would also be helpfull. My tach did not work at all when i bought the 79. Now its working but incorectly. At idle its reading 3500 and if you give it any gas at all it pegs it. I still have the tach from my 78, but I would like to try to see if the one on the 79 can be adjusted (fixed) before changing them out. Any advise or links would help. The car has a petrotronix coil i think. Thank you in advance. :conehead
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
Re: headlight problems ect... (A78Corvette)
Well based upon the way the tach is reading, I'd have to say first off that the engine has been replaced with a gas turbine. It sounds like the sender on the back of the tach has gone kaput.
As for the headlights, start by tracing your operating vacuum lines from the manifold all the way to the headlight vacuum motors. You need to isolate the problem to either the control or the operating system. You do this with your vacuum testor. If the operating system has vacuum where it's supposed to be, then you start working the control side. A simple control side test is to remove the vacuum line from the control valve. The small vacuum line to the control valve's function is if vacuum is zero, it opens the headlights. Test the line with the switch on or the manual valve to open. If there is vacuum present on that small line, then you have a problem in the control side. If you have the manual, then follow the steps. It's really not as hard as it first seems.
Your low-beams being out is likely going to be a burned out bulb or the dimmer switch circuit is bad. You need to test this with a multimeter on the bulb socket.
As for the headlights, start by tracing your operating vacuum lines from the manifold all the way to the headlight vacuum motors. You need to isolate the problem to either the control or the operating system. You do this with your vacuum testor. If the operating system has vacuum where it's supposed to be, then you start working the control side. A simple control side test is to remove the vacuum line from the control valve. The small vacuum line to the control valve's function is if vacuum is zero, it opens the headlights. Test the line with the switch on or the manual valve to open. If there is vacuum present on that small line, then you have a problem in the control side. If you have the manual, then follow the steps. It's really not as hard as it first seems.
Your low-beams being out is likely going to be a burned out bulb or the dimmer switch circuit is bad. You need to test this with a multimeter on the bulb socket.
Melting Slicks
Joined: May 2000
Posts: 3,280
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From: Virginia Beach Virginia
Re: headlight problems ect... (gerry72)
Gerry has offered good advice.
I would first disconnect your hoses from the relay valves. With a vacuum pump, ensure that you can raise and lower the headlights. If you can directly operate the headlights in this way, try hooking the pump to the actuators and see if you can get the same results. I had to replace both of my relay valves and spent hours trouble shooting other areas when the problem was really there.
Stephen
I would first disconnect your hoses from the relay valves. With a vacuum pump, ensure that you can raise and lower the headlights. If you can directly operate the headlights in this way, try hooking the pump to the actuators and see if you can get the same results. I had to replace both of my relay valves and spent hours trouble shooting other areas when the problem was really there.
Stephen
