could this be my headlight switch? the lights will not come up unless I pull the over ride under the dash. I can raise and lower them with that an they will pop up strong! then when I have the lights on an push the over ride in they will stay up untill I push the lights off. I hear a hiss in the dash at the head light switch. is that puppy bad?
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Re: C-3 70-72
I would check to see if the vacuum hose to the switch is unplugged. If it is not, plan to spend a few bucks and buy a switch.Dick Whittington -
Re: C-3 70-72
Dick,
you know any tricks to get at that switch with out droping the dash?Comment
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Re: C-3 70-72
You can reach the headlight switch without pulling the dash. It helps if you don't have lumberjack hands though. Go to Ecklers and look at this site:
and you can see the two nipples, in the right hand photo, that are in discussion. Make certain that both rubber tubes are connected. If they are you need to start looking for vacuum leaks but I vote for a disconnected headlight tube.
Gary
72 LT1Comment
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Re: C-3 70-72
Gary,
thanks that link is not working for me. I will need to get a friend to do that he has small hands as I am 6'4 with large hands.Comment
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Re: C-3 70-72
I see that the link didn't completely highlight. If you will copy the whole link, including the non-highlighted portion, it will work - I just tried it.
I have normal sized hands for a 5'11" guy and it is tight back behind the dash. I can see how you might have trouble.
GaryComment
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Hum...
This is the way the HL vac circuit works:
Vac flows from the intake manifold through the filter, through the check valve and then makes a 2-way branch. The large diameter hose on the output of the check valve routes vac for the servo side of the system (vac that does work opening/closing components). The small diameter hose on the output of the check valve routes vac for the control side of the system (vac that tells the servo components when to actuate).
The small diameter control vac hose routes immediately through the firewall and into the cockpit where it makes a T-split with one side serving the wiper door and the other serving the headlight. The underdash over-ride switches are in series with their respective control switches (wiper door relay on the back of the tach and headlight switch).
The control algorithm is if either control path is vented, the downstream servo systems actuate (wiper door opens or headlights pop up). Therefore, if either the over-ride switch OR the control switch vents vac, the item being controled actuates.
So, for the HL switch not to open the headlights, it'd have to be bypassed vs. having a loose or leaking hose...
The fact that the control side of the vac system uses small diameter hoses AND there's no vac reservior to fill, is what biases the system (forces the control side of the system to 'power up' first) and keeps headlights and wiper doors from 'winking' or 'dancing' on engine start-up.Comment
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