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1977 Continental Lighting Issues

Hi Bill,

I know there are a plethora of headlamp posts on this site already, but haven't come across any with exactly these symptoms, so I figured I'd reach out. Anyway, last month I picked up a 1977 Lincoln Continental Town Car 4-door sedan. It is equipped with the Auto-Dim and Auto-Lamp options. I was assured by the seller that the headlights worked as expected, but stupidly did not check this before taking delivery. At one of the fuel stops on the drive home, I realized I probably should check them. This is what I have observed. - Prior to testing the headlights, the door covers were shut. - Both the auto-lamp and auto-dim functions are disengaged via the ring controls. - Pulling out the headlight switch opened the healight doors and engaged the dash lights and all parking lights, but no headlights. - Pressing the floor mounted high-beam button while the headlight switch was pulled out had no result. Not sure if there is a high-beam indicator light in the instrument cluster on these cars, but if there is, it did not come on. - Not sure if this is helpful, but the door buzzer indicating that the headlights are on does work when the switch is engaged. - Pushing in the headlight switch turned off the dash and parking lights as expected, but the headlight doors did *not* shut (and haven't shut since -- initial test was performed on Nov. 23rd) - I verified that the auto-lamp seems to operate correctly; engaging the system via the turn ring (while dark out) had the same effect as pulling out the headlight switch, and I could hear a relay click somewhere inside the dash. - I noticed that both outer/low-beam lamps had cracked along the lens, so I picked up a replacement lamp in case the original bulb was burned out. Same behavior observed after replacement. As mentioned, the system governing the headlight cover position has been sending the "open" signal ever since I first tried to test the headlights, regardless of the headlight switch position. That has been a bit cosmetically irritating, so I swapped the two vacuum lines behind the left headlamp to shut them. This works, but only to a point. I'm guessing that the line supplying "shut" vacuum must have a dedicated valve closer to the headlight covers that keeps vacuum applied even when the vehicle has not been run for awhile, instead of relying on system-wide vacuum to keep the doors shut. As it is now, with the lines swapped, the covers do stay closed while the car is running, and for about 12/24 hours after it is shut off, after which I assume the system-wide vacuum is bled off, and the doors open. Considering that, before the first headlight test, the vacuum lines were in their correct position AND the covers were shut, along with the fact that they remained shut while the car sat for days at a time prior to being sold, lends credence to the seller's claim that the headlights were functional beforehand. So whatever failed must've done so right around the time of the first test. I do have the 1977 FoMoCo shop manual, and have tried to digest some of the headlight wiring system, but it's been a bit overwhelming... indeed, nobody could accuse those authors of including unnecessary information. Hopefully the details above provide enough information to narrow down the possible culprits, if not the actual faulty component. But at this point, I'd be happy with any suggestions, be they items to test, any helpful hints on how to do so, or even any components that I *don't* need to test, if the provided info indicates full operation of one or more bits.

Thanks for your help!



Hello Daniel -

The first step that I would take is to contact the seller and ask him what he knows regarding the headlights and the headlight doors not working. He should know something about this!

Keep in mind that if the headlamps have been swapped to high output units they may have a power draw that exceeds the circuit breaker capacity. The breaker is located inside the H/L switch. Also be aware that if you are not very experienced and are doing the diagnosis yourself and have a problem reading and understanding the manual you could be in for some disappointments .

I would first begin by testing for power at the headlight electrical plugs. If there IS power to the units as designed with the switch in the on position, the ground wires should be examined to ensure that the system has the necessary grounds in place. If there is NO power at the lights the next step should be to test for power into and out of the foot dimmer switch. They are known to fail and seize from lack of use. If that foot switch has no power to it, the next step will be to test for power to and from the headlamp switch for the headlamp circuit. With the AUTOLAMP option there should also be a relay and an inline fuse included in the circuit (page 32-15-2). This is another reason that the correct wiring diagram is a must. Keep in mind that meaningful diagnosis in a logical sequence along with the correct wiring diagrams and test equipment is the best approach. We have in stock or access to any needed parts that you require. Good luck to you with an easy repair.