Trouble with headlight doors?

[73 T&C]

Well, after driving the car for six months I have a new bug....

Headlight doors are not opening up correctly when the headlights are activated.
It happened early on and after opening them manually a few times the problem went away until now.

Symptoms:

Headlights come on, doors try to open but get “stuck” somewhere in the cycle. Relay in dash starts “beeping”, ammeter shows slight drain.

Temporary remedy involves manually working the knob under the motor that shows little resistance and occasionally “helps” with the motor turning for a few quick spins.

Turn off the lights and the doors close flawlessly.

First diagnosis:

FSM says nothing helpful for diagnosis only which parts need replacing. It does explain the function very well.

Thinking I have a bad connection at the headlights switch.

 

[Pete Kaczmarski]

Tap onto the headlight motor gently with a hammer when they are partially opened. If they open I suspect some minor corrosion at the base of the armature which is close to vertical. I have never taken my motor apart on my '79 New Yorker but when its colder in the fall this will happen.

 

[Yeahrightgreer]

To test if it it really is a voltage problem - first make sure you have a good ground for the motor. Use the battery as a direct source and run a jumper wire to the leads on the motor. If they fully open you know your problem is somewhere in the wiring. If not - it’s probably something internal to the motor

 

[Big_John]

The motors come apart pretty easily. Chances are, you just need to clean the commutator and brushes. The bottom bearing gets a little dry too.

A couple guys have taken them apart here. A search might show some pics.

 

[Davea Lux]

First, try disconnecting the plug that goes into the headlight motor assembly. Next, take a wire with alligator clips and hook one lead to the positive terminal to the battery. Take the other end and touch it to one or the other other the motor plug terminals. One lead opens the headlight doors, the other closes them. If the headlight doors are closed one of the plug terminals will be inactive, if that is the case, switch to the other terminal and the doors should open. The process can be reversed to close the doors. If the headlight doors still will not open all the way, the motor or the switch plate is defective and the motor will need to be removed for service. If the doors open part way and then you get a grinding noise, the gear drive assembly for the motor is stripped and will need to be replaced.

There are two limit switches that control the opening and closing functions for the motor assembly. These are located under the plastic cover for the gear drive (rectangle shaft goes thru the center of the gear assembly). Turn the manual knob to center the travel of the gear assembly, there are two indexing marks that are used to center the gears. Failure to do this will result in the switch plate being damaged as the cover is removed. Carefully inspect the switch contacts and the gear set for damage and repair/replace as necessary.

I do not think it is a good idea to remove the armature cover as the brush holder is made from cheap bake-lite composite which is easily broken and replacements are not available. You can test the relay unit with a mulitmeter by hooking one lead to the other end of the motor harness. Turn on the ignition switch to the on position and turn on the headlight switch, one lead should supply 12v, turn off the headlight switch and the other lead should now supply 12v with the key still on. This will tell you if the relay is cycling. If the contacts for the relay are burned or corroded, you will probably get less than 12v on the multimeter. If so it needs to be replaced.

You noted a noise coming from under the dash, that is probably the circuit breaker that is built into the headlight switch. These usually trip because of excessive load, so if the motor is getting stuck, that is probably the cause. The circuit breaker is not a very durable item, so you may have fried it. Do the above tests and report back.

Dave

 

[73 T&C]

First, try disconnecting the plug that goes into the headlight motor assembly. Next, take a wire with alligator clips and hook one lead to the positive terminal to the battery. Take the other end and touch it to one or the other other the motor plug terminals. One lead opens the headlight doors, the other closes them. If the headlight doors are closed one of the plug terminals will be inactive, if that is the case, switch to the other terminal and the doors should open. The process can be reversed to close the doors. If the headlight doors still will not open all the way, the motor or the switch plate is defective and the motor will need to be removed for service. If the doors open part way and then you get a grinding noise, the gear drive assembly for the motor is stripped and will need to be replaced.

There are two limit switches that control the opening and closing functions for the motor assembly. These are located under the plastic cover for the gear drive (rectangle shaft goes thru the center of the gear assembly). Turn the manual knob to center the travel of the gear assembly, there are two indexing marks that are used to center the gears. Failure to do this will result in the switch plate being damaged as the cover is removed. Carefully inspect the switch contacts and the gear set for damage and repair/replace as necessary.

I do not think it is a good idea to remove the armature cover as the brush holder is made from cheap bake-lite composite which is easily broken and replacements are not available. You can test the relay unit with a mulitmeter by hooking one lead to the other end of the motor harness. Turn on the ignition switch to the on position and turn on the headlight switch, one lead should supply 12v, turn off the headlight switch and the other lead should now supply 12v with the key still on. This will tell you if the relay is cycling. If the contacts for the relay are burned or corroded, you will probably get less than 12v on the multimeter. If so it needs to be replaced.

You noted a noise coming from under the dash, that is probably the circuit breaker that is built into the headlight switch. These usually trip because of excessive load, so if the motor is getting stuck, that is probably the cause. The circuit breaker is not a very durable item, so you may have fried it. Do the above tests and report back.

Dave

Thanks Dave,

Your description helped me also see something else.

The lower bearing may be dry and causing it to stick when opening as that movement appears to put downward pressure on the shaft. I noticed a bit of play there. It would also explain the buzzing under the dash as the circuit breaker struggles with the added load. And why closing works flawlessly... no downward pressure on the shaft.

But I’ll start and confirm this with the very logical steps you’ve outlined.

Javier.

 

[Robert Saigh]

On my '77 NYB the headlight doors open up but will not close as with most of the Formals. I usually just use the mechanism by hand at the bottom of the motor and wind back up until they're all the way closed. Any ideas?

 

[BLIMP]

If I remember correctly, I've read others mention adding a few drops of oil to the motor through the hole near the knob on the underside.

 

[Davea Lux]

On my '77 NYB the headlight doors open up but will not close as with most of the Formals. I usually just use the mechanism by hand at the bottom of the motor and wind back up until they're all the way closed. Any ideas?

You probably have a bad switch plate in the motor. The limit switch plate contacts sometimes carbon up and do not make contact. Test the motor as outlined above and then remove if necessary to service the limit switch.

Dave

 

[73 T&C]

Went through Dave’s list today. Pulled the plug and powered the motor with my power probe... went up/down but really noisy and a little slower on the down.

Hit the top of the nob where shaft comes through motor housing with a little WD40 using the metal flex tip and lubed the bushings for the doors also put a few drops of oil on the wheel for the shaft. Quieter now and faster on the down.

Plug for motor was a little hard to get to but I managed.

Looked for a hole to lube the bottom bearing /bushing for the motor. Finding none, I sprayed some WD40 into the tab joint at the base after removing rubber seal blob. I think it got in there.

Checked the switch side of the plug and read fluctuating voltage from .6v to a full 13v. Checked the circuit breaker under the dash (royal PIA) and it was a bit loose. Tightened the plug and that seems to have cleared the problem.

Checked the ground to the motor and it was fine. Cleaned and put some dielectric grease on the ground just for good measure.

Back to full function.

 

[BLIMP]

Way to go Javier! When I had my headlight motor out I used some sewing machine oil and it made a noticeable difference, glad to hear you were successful.

 

[73 T&C]

ThuuuuuWAP!.... that’s the sound my headlight doors make as they bang open and closed now.

I guess the lube finally worked itself into the bushings and gearbox.

Man these things are loud!

I had to check that all the rubber bumpers were still there (they are).

 

[Robert Saigh]

That's what my '75 Imperial headlamp doors sound like going up & down!!

 

[BLIMP]

That's what my '75 Imperial headlamp doors sound like going up & down!!

Being so loud helps me to know they have opened and closed properly when I use them during daylight hours

 

[Robert Saigh]

^Yes!

 

[ImpJay]

Being so loud helps me to know they have opened and closed properly when I use them during daylight hours

Exactly what you taught me: a clunk avoids all guessing.