hidden headlight gears....info

[Big_John]

It's not just an "Urban Legend", at least in the 70 FSM. It specifically says not to run the motor out of the car. They did specifically mention the limit switches.

What's really funny is that in some later year FSMs, they tell you it's OK to run the motor out of the car. I had a screen shot of one, but can't find it now.

And here's the link for the replacement gear. Products Note that the gear teeth are only on one side, rather than the original that has teeth completely around it. That will still work as it only runs 180 degrees and you can flip the gear to the unworn side if you want.

From my experience, and reading when my "rebuilt" motor failed, the biggest problem with these motors is the bottom motor bearing. It gets dry and dirty and then the motor won't turn. Mine was full of sand from it's trip through the blaster by the "rebuilder".

 

[ceebuddy]

I agree with Big_John, on one of my cars the motor wouldn't budge. I took it apart and it turned out the shaft had developed surface rust and stuck in the bushing. I cleaned everything, put a tad of grease here and there, put it back together and it worked fine ever since.

 

[CanCritter]

Lots of reading for you.
View attachment 345536 View attachment 345537 View attachment 345538 View attachment 345539

How my car was wired. The relay is under the battery tray. Your 71 GT is probably the same.

View attachment 345540

Note the alignment.

It's not just an "Urban Legend", at least in the 70 FSM. It specifically says not to run the motor out of the car. They did specifically mention the limit switches.

I bet if you did like Bob said & just touched momentarily you could get away with it. I just test em' on the car since I have 2 with hiddens. To help simulate a load you could put a square-shanked screwdriver in the drive slot &give it some resistance to be safer.

Remember to turn the manual knob back to the alignment marks after testing, this puts the motor in the middle of it's range & you lift the doors to the halfway open position to install it. At least for a 70 anyway, I'd think the other years would be similar.

To clarify that a bit.....look at where the square shaft goes thru the gear housing to each door, There a little pip mark on the outer section that doesn't move & a pip on the center that turns. You just turn the manual knob at the bottom & line the 2 marks up with each other.

Bolt it up, slide the square drive thru, lift the doors ( you can do 1 at a time ) until the square drive falls into the slot in the doors ( doors should be about the half way open point ) Don't forget the spring steel retainers that slide over the square drive & hold them to the doors. Once both are hooked up, connect the wires , get in & turn the key on...doors should close if everything is working.

Headlights will come on without the key on but the doors won't open until the key is on.

looks like schools in for me..l have some studying to do ....great info Bill ..
Thanx folks....
Guessing first thing l'll do is test motor now in car as mentioned above to see if it works….
Motor in car now is PN3431026...not sure what car its from or has similar cam in it....have correct motor 3431 437 but it has no plastic gear or cam in it...
Am hopeing motor in car works and will test that first thing Monday morning when it warms up...my water in garage is frezzein so its cold down there right now...
if motor works will have to trace wireing back to relay ect..haven't touched anything under dash re wireing so it should be fine and oem...big thing lm thinkin is ensuring l have good grounds to everything...

 

[CanCritter]

seen....

 

[Fury440]

What's really funny is that in some later year FSMs, they tell you it's OK to run the motor out of the car. I had a screen shot of one, but can't find it now.

And here's the link for the replacement gear. Products Note that the gear teeth are only on one side, rather than the original that has teeth completely around it. That will still work as it only runs 180 degrees and you can flip the gear to the unworn side if you want.

From my experience, and reading when my "rebuilt" motor failed, the biggest problem with these motors is the bottom motor bearing. It gets dry and dirty and then the motor won't turn. Mine was full of sand from it's trip through the blaster by the "rebuilder".

John I think the difference is the types of gears and limit switches used. I've seen at least 4 different limit switch setups, some allow the gear to rotate 360 deg, others rotating beyond the limit switch self destructs the switch and or the gear. Basically the limits of door travel act as rotation stops which in a sense define the motor travel in degrees.

 

[73 T&C]

I agree with Big_John, on one of my cars the motor wouldn't budge. I took it apart and it turned out the shaft had developed surface rust and stuck in the bushing. I cleaned everything, put a tad of grease here and there, put it back together and it worked fine ever since.

Same here with mine. It would close fine but “stick” when opening.

With power to the motor to open, it would turn fine if I pushed up on the manual override. Some penetrating oil and turning it by hand a few times to free it up and some heavy bearing grease on the exposed shaft... it started working fine and it’s been working well for the last year.

 

[CanCritter]

welp spent cpl hrs tonight on headlights..ie hooking power up directly from battery...
first result motor works,,,would open door perfectly...closeing it wanted to continue...
Had motor in and out half a dozen times..tab set as directed...
took motor apart to check cam,,(white)...gear full...reassembled...now only gos down lol...think l had contact wrong on one using 437 motor for refrence

B is correct with contacts on top...
Have red cam so tried it with white gear...same results

tried to stuff gear and can into proper 437 motor but it wouldn't go due to cam stop difference inside motor..took me cpl mins to sort out wth ..whys it not fitting

D proper 70 gt motor with half gear...pic below from welder guy

so l guess lm looking for the half gear if anyone has one kicking about....

note of interest....both white gears same PN however one has square hole for bar and other has oblong..

anyway guess lm huntin a half gear and throw it in the original 437 motor which l believe is original GT motor to car given the 3431 437 PN...
anyway once l get motor to open and close where its supposed to will work my way back through wireing to see whats up with power...sigh..

 

[CanCritter]

again with Marlows pic noticed contacts were on top as well..progress…

A wrong
B correct

 

[ArnieJr]

If the unit is installed in the car, there are three leads that should be present at the motor connection. One wire is grounded to the case of the motor. When the headlight switch is in the "on" position, one of the two remaining leads will be hot. When the light switch is turned off, the other lead will be hot to close the headlight doors. Key needs to be on so there is power to the relay and the headlight plugs need need to be installed. The headlight filaments supply the ground for the relay.

Dave

I think (and hope) that my door issues are related to the headlight. When I bought the car, they would open, but not close and the low-beam bulb was burned out on both sides. I replaced them with Sylvania H5006 and I'm assuming H means Halogen and been told they won't work with halogen lights. I found some on CarID ( Philips® - 5 3/4" Round Low Beam Chrome Factory Style Sealed Beam Headlight ) and may order those, but is there a way to ground the new ones I have now, at least to see if that's the problem. My electricity knowledge is minimal, but could I run a wire from the frame to a ground on the headlight and which prong would it be? Forgive the noob question, but I'm lucky if I don't electrocute myself changing a ceiling fixture.

 

[Davea Lux]

I think (and hope) that my door issues are related to the headlight. When I bought the car, they would open, but not close and the low-beam bulb was burned out on both sides. I replaced them with Sylvania H5006 and I'm assuming H means Halogen and been told they won't work with halogen lights. I found some on CarID ( Philips® - 5 3/4" Round Low Beam Chrome Factory Style Sealed Beam Headlight ) and may order those, but is there a way to ground the new ones I have now, at least to see if that's the problem. My electricity knowledge is minimal, but could I run a wire from the frame to a ground on the headlight and which prong would it be? Forgive the noob question, but I'm lucky if I don't electrocute myself changing a ceiling fixture.

Grab a test light, turn on the headlights and unplug one of the low beams. These are a simple 3 wire circuit, usually the center lead is the ground as the two bulb filaments share the common ground. One of the side leads will glow the test light when the light switch is on and the dimmer is in the low position. The opposite lead on the plug will glow the test light with the dimmer in the high position..
Now hook the test light to the center terminal of the plug and the + terminal of the battery. The test light should glow if you have a ground. If so, you need to rig a load from the ground wire to the terminal that was powered on low beams. If you have an old tail light socket with a bulb, needs to be a filament style bulb, not LED, hook the two wires from that to the ground and the dim terminal the block and see if the headlight doors will cycle.

Dave

 

[CanCritter]

K well it took 6 motors and Graham and Marlows help to sort my way through this mess.....now have a working motor to open and close doors.....cant seem to post pics from phone ...bugger..cant load the pics...not sure whats goin on here these days...…
anyhow have motor that works in place...traced wireing back..all good back through the fuse block to the relay at which point am having issues....stuck at relay

can put power to "B" and have my doors open and close normally…
with lights on...key off have power to "A"
with lights on key on have power to "A" "C" "D"
however no powers getting through to "B" to operate the hidden headlight motor
have tried two hidden headlight relays similar to one shown below and nada..
are both hidden relays toast?? thoughts?

 

[Big_John]

FWIW, the relay is a little screwy to figure out.

It gets ground through the headlight filaments. So for it to work, it needs to have the headlights wired in and operational. ALL of them have to work right too.

If there's a bulb out, it'll open, but won't close. IIRC, the case of the relay needs to be grounded too.

 

[CanCritter]

k replaced a hi beam light that was missin,,relays grounded 8 ways of sunday and nada so far...wireings right and supplying power..all head lights working..hi beams workin...checked the 30 am fuse for continuity and it seems fine..
gona swap out this relay for other and try it one more time and see what happens....

 

['69FuryIIIConvertible]

I must say, you gentlemen are an absolute wealth of knowledge, I bookmarked this thread for when I have a look at my headlight motor for my 70.

The troubleshooting and Q & A here in this thread is excellent.

Nick

 

[Davea Lux]

k replaced a hi beam light that was missin,,relays grounded 8 ways of sunday and nada so far...wireings right and supplying power..all head lights working..hi beams workin...checked the 30 am fuse for continuity and it seems fine..
gona swap out this relay for other and try it one more time and see what happens....

The relay in the photo shows some corrosion, the contacts inside might be in similar condition. Try carefully removing the cover to inspect. You can clean the contacts with a point file.

Dave

 

[Welder guy]

Here are some close up pictures of a working motor , half gear and points for reference .

 

[Welder guy]

 

[Welder guy]

 

[CanCritter]

following Marlows pics above saved me alotta heartache putting motor back together right...again thanx Marlow...

k...am assuming both hidden headlight relays l have are non functioning so have gone out and grabbed a 30 amp bosh type relay...is there any reason l cant get away with one relay at same position??
...have seen diagrams of hidden headlights with 2 relays and its confusein the crap outa me...not that that's any surprise...

 

[Big_John]

following Marlows pics above saved me alotta heartache putting motor back together right...again thanx Marlow...

k...am assuming both hidden headlight relays l have are non functioning so have gone out and grabbed a 30 amp bosh type relay...is there any reason l cant get away with one relay at same position??
...have seen diagrams of hidden headlights with 2 relays and its confusein the crap outa me...not that that's any surprise...

One relay. Go back and read the link in my previous post. (Post #18) Easy with no modifications to wiring involved.