1970 Mark III headlamp doors operating backwards

[FrogOne]

When the headlights are off (not illuminated) the headlamp doors are open; when the headlights are switched on (illuminated) the headlamp doors automatically close in front of the illuminated headlights. Turning off the headlights automatically opens the headlamp doors.

Any idea what is wrong here?

 

[mark95man]

When the headlights are off (not illuminated) the headlamp doors are open; when the headlights are switched on (illuminated) the headlamp doors automatically close in front of the illuminated headlights. Turning off the headlights automatically opens the headlamp doors.

Any idea what is wrong here?

I was once really into the 69-71 MARK III's having one new 1970 (sold in 2013) + 75 used. All of them are now gone along with all of my manuals. So we're on my fading memory now.

Let's assume you just purchased this car and the covers are working wrong OR you replaced the headlight switch. From what I recall the headlight switch activates the covers via vacuum hoses attached to that switch. OR someone did work on your car messing up those vacuum lines.

Do you have a complete shop manual for this MARK III including the electric and vacuum schematics? These are available on eBay or online but you'll have to search for the online forum. FYI--the factory installed rubber hoses were color coded for this type of problem. But someone could have changed out the hoses which will make this a fun job. Most repair shops do NOT know this car, so it's a do it yourself project unless you want to pay someone to attempt to learn what they don't know. My suggestion--buy the manuals and trace out the lines to find what's wrong.

 

[FrogOne]

I recently bought the car; I didn't replace the headlight switch. Fortunately the car did come with the original owner's manual and a complete set of the 1970 Lincoln Continental shop manuals, including electric and vacuum schematics. So I'll now proceed as you have advised, hoping that the original color-coded vacuum hoses are still there.

I'm hoping that the hoses are simply connected wrong, by some previous mechanic. If not, then I assume that I'll have to replace the actuator behind each door. It's some kind of vacuum canister with two or three vacuum fittings as well as a mechanical arm connecting to the headlamp door itself. Unfortunately I can't yet find this actuator/canister thing or any mention of the headlamp doors in the manuals. Thanks again.

 

[John Harbour]

either swap the outer hoses on the switch(not the middle one)... or swap lines going to the headlamp covers(cut and swap connections of the two hoses leading out of the firewall and goes to the headlamp covers.)

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[Jackwild11]

3 hoses come off the switch. Closest to the knob is GREEN, middle WHITE, lastly YELLOW... Connect them to the vacuum junction box at the firewall (above
the dimmer switch) which is color coded.