1972 car.

I noticed one of the electrical switches that seems to have something to do with headlight door position, is broken.

It is available from the usual suppliers, so that isn't a problem, but what purpose does that switch serve?

Thanks,
Doug

 

It just tells you the headlights are in the full up position. If the yare not there is supposed to be a light on the dash that stays lit until the lights get put in the full up position.

 

Hi Doug,
The switch signals that the headlight door is completely open and turns off the headlight warning light in the top of the center gauge cluster.
I believe they're availible from various venders.
Regards,
Alan

Added PS: You beat me G while I was looking for the picture!

You can see the door linkage has depressed the 'button' on the switch to turn the light off.

 

Someone please correct me if I'm wrong - I'm just taking an educated guess here. I've thought about why the switch is needed, and this is the best I can think of.

The headlights being vacuum operated, rely on vacuum generated by the engine. The amount of vacuum generated by the engine will vary, and it will go down with high RPM.

So suppose you are driving at night, and your headlights were not locked. You are driving at high rpm's for an extended period of time. Your vacuum tank has a bit of a leak. Your headlight might possibly go down while you're driving.

If the headlight are up and locked, there is no chance of decreased engine vacuum causing them to go down.

 

Well Alan I am glad that you posted this! I have replaced one of these swtiches on my 75, and the light on my dash still turns on. Now I can see how it all works and will be troubleshooting it coming soon.

Can you press the 'button' by hand to see of the light turns off?
Thanks!
Ben

 

Pressing the button should turn the light off if the other switch button is pushed.
Unplugging the wire from the switch will also turn the light off.

Mashman-sounds reasonable to me.

 

Well, thats no good. My light came on when I was missing a switch... What else will make this light come on?

 

When the white/green striped wire goes to ground through the black wire the light in the dash turns on.
Pull both plugs off the switches and see if the light goes out , if not the white/green is grounding somewhere.

 

Ok thanks for the tip. Its ALWAYS fun to search for grounds lol.

 

Alan 71
Thanks for the photo. I have been staring at this light on my 75 for two years when I drive at night. Now I have a photo to help me find out how to check or replace the switch.

kdf

 

Vacuum applied to the front side of the "headlight actuator assembly" pulls the headlamp clevis forward raising the headlight assembly. Once it reaches a certain point it extends the "knee joint" to overcenter, locking the headlight assembly in the up position. At this point you could remove the vacuum and the headlight would remain locked in the up position (the springs will actually hold it in this position until acted upon by a stronger force). As the "knee" goes overcenter, the a fore mentioned switch is positioned against a stop and should extinguish the warning light on the center dash (assuming the other assembly performs likewise).

In order to lower the headlights, vacuum is applied to the back side of the "headlight actuator assembly" and the headlight clevis is pulled to the rear retracting the "knee" from the overcenter position and ultimately lowering the headlight assembly. Once the knee moves back overcenter, the assembly could almost fall to the closed position by gravity.

If you should find yourself in a situation where the headlights won't retract, you only need to carefully reach up into the assembly and push the "knee" back overcenter and gently lower the assembly.

The only sensible reason for the fully open switch is to let you know that 1) both headlight assemblies are fully up and locked (overcenter) and 2) to assure you that your headlights are positioned correctly to illuminate the road in front of you as required by most State inspections.

Good luck... GUSTO

 

Right. If the engine was at such high RPM that there was not enough vacuum to operate the lights, power brakes probably would not work either. Loss of vacuum from a leaky system usually means they simply freeze in the last position.

The warning light indicates that your tray tables are not in the upright and locked position prior to landing.

 

Open the hood and reach under the surround.