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There seems to be a lot of headlight issues in here.

Several years ago as part of a restoration I changed the nylon gear to the bronze one and the headlights came up just as designed. I never drive at night but I might, so recently I've cycled the lights and although they come up there is a very different gear sound. I cycled the lights twice and then raised the car and started to hunt for the reason. The ignition was completely off. I reached in to wiggle the motor and found it too hot to even touch and there was some slight smoke .. probably from heated lube on the big gear. I quickly disconnected the battery, disconnected the small wire (ground?) on the motor and here I am.

I don't think the motor was still hot from me operating it (it had several minutes to cool) so it seems there was power to it even with the ignition off. The buckets were down and the limit switch looked closed. The motor and switches are original to the car (72 pre-L.

Any ideas? And is there a connection between this issue and the different gear sound (I'm guessing yes)?
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Original Post
ok try:
- + power OFF the bat
- light switch ON (full for head light)
- ignition into run

then connect to bat+ lossely step on step..see what happens,
- first it goes up and up..and should be limited by swich fisrt..then by end point screw as applies
- bat+ off at any up going position or end point up
- then light switch OFF
- bat+ again temp (on/off etc.) on it goes down and down and then does it stop per down switch OR per limiter screw?

(this is by the way I did tune end position for up and down)

Last edited by matg
IF the motor is still driving the bucket into the stops, according to Joe’s drawing, you possibly have a dual failure...

The ignition switch could have failed first, and the limit switch stopped interrupting power to the down motor when you cycled the lights... all this assumes no one modified any of the wiring.

Not sure where the connections are, but if you can check the output at the down limit switch, while cycling it between limit “off” and “on” (buckets manually up part way, motor disconnected), it might give more clues...

Good luck.

I think this is a case of "when you hear hoof beats think horses, not zebras." I think the motor was extremely hot because it was working too hard raising the lights. An hour later, with the battery disconnected, the motor was still quite hot .. all that copper. Maybe the bearings for the headlight "rod" are sticking or maybe the small gear box is jammed in some way.

The circuitry appears OK .. lights go up and down with the switch and stop when they should. The lights themselves go on and off. The lights go up slower than normal and the gears sound like they are working hard suggesting a lot of friction somewhere. I'm going to pull the motor and gear box and see if anything is stuck or jammed. Hopefully the motor hasn't burned out. But first I will reconnect the battery and see if the motor heats up without me trying to operate the headlights (no touching the headlight switch). If it does then there is a circuitry issue.

Stay tuned.
Your's is a Pre L so diagram should be true, but just finishing up today on a problem, and checking (3) L model cars, the diagram does not apply. The relay is commanded by the key switch, and not by the head light switch. L models use a circuit breaker not shown in the diagram, and three black wires. The red/black wire is not used.
Hot news flash (no pun intended). My mechanical friction hypothesis may be wrong. I reconnected the battery (and the small wire to the motor). Without turning on the ignition or the headlight switch the motor began to heat up. So power is being applied to it. It doesn't make any noises, just gets hot .. I didn't leave it connected long enough to get really hot like yesterday when I operated the lights.

Time to look at that circuit diagram. Where is the headlight relay located? I'll confess to not being a good (or even half-assed) automotive electrician. All help welcome.
were the lights UP or DOWN?

did the lights move, if so which way

during my career, I had the rep of always providing the worse case for simplest of syptoms

IF a limit switch failed to shut the motor off, the current when the motor becomes "locked Rotor" is GREAT. I don't have real world experaince, but I would guess the current would burn a fuse....(So you might have some damage to your key switch)

Fuse 10 is actually off the ACC position on the Key, so be sure not in that position
the other item on F10 would be the AC/Heater blower, might check to see if it comes on with key off

Is it possible your wiring has been modified?
Here is a bit more info. I pulled the power wire off of the headlight motor and checked the voltage with the ignition OFF (not even with the key in the switch) and the headlight switch OFF. Only the battery connected. There is 12V being supplied to the motor wire. Assuming this is not suppose to be that way, this suggests that for a pre-L the only direct source comes from the ignition switch. The headlight switch, although "upstream" from the ignition switch, only actuates the relay and is not directly connected to the motor. This according to the above circuit diagram.

Bosswrench said once that the motor is internally grounded but I don't see how that matches the above wiring diagram that shows the motor grounded after the limit switch. But I'm not good at reading such diagrams.

So it seems that possibly the ignition switch, even when off is still supplying 12V to the motor (and everything else?), however, my battery stays charged. Maybe it is a very recent thing. So I have several things to study: 1) ignition switch, headlight switch, headlight relay, and maybe the limit switches.

Any ideas where to start? The relay seems easiest just by listening.
I can only comment based of drawings, however I dug up my pieces of 5177 and found the motor drive.

My motor has two leads, (no ground per say). Thus to go one way the Male is connected to +12VDC and the Female to ground through the DPDT Relay. to go the other way, the Relay changes the polarity to the leads.

I can see where someone would change the wiring to remove the headlight motor of the key switch for two reasons
1) remove that high current load
2) headlights can be turned on without the key and thus should open (could damage paint if they don't)

if you have connect your volt meter to the wire side of the motor connectors, with the buckets at mid stroke, you should see 12VDC across the wires, turning the head lights on should then reverse the 12VDC's polarity

with the lights off, seeing 12VDC across the wires (Yellow wire +), finger the limit switch for buckets closed should remove the 12VDC
with the lights on, seeing 12VDC across the wires (Brown wire +), finger the limit switch for opened should remove the 12VDC.

If you can provide which color wire goes to which motor terminal, would be apprecaited


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That pic was a great help. I managed to squeeze in and found the second lead. I think Bosswrench is still correct .. the motor is internally grounded and the two leads control the direction. The one that is "hot" in my scenario is yellow and the other one is black. I should mention that the lights are currently down.
I checked the voltage to the black lead with the battery connected and it is zero (remember, the yellow has 12V). Then I turn on the headlight switch and the headlights themselves come on (in the retracted position) which suggests that the headlight switch is OK. Also with the headlight switch on, 12V then appears on the black motor wire. Clicking the up limit switch doesn't change the 12V. Interestingly, when I checked the voltage on the "hot" yellow wire with the headlight switch on, my meter turned into a random number generator .. it could not settle on any reading. Go figure.

Maybe the important thing is that with motor wires disconnected (I don't want to operate it) I turned on the headlight switch and could not hear any relay click. I did it several times. So now I'm wondering about the relay although maybe it only works with the ignition on. So I still need to do some measurements with the ignition key in the Run position and see what happens. This is like CSI.

I apologize for this long thread but I really appreciate the input.
For me, Not CSI, but like olden days assisting with “Root Cause & Fault Tree Analysis”

When I suggested fingering the switches and noticing the voltage go away, that was measuring the yellow wire with respect to the “black” wire. The way I read your reply, I assume you took your voltage measurements with respect to chassis ground.

When I had to quite work, I tried consulting via phone/email BUT I got too confused (like now).

But if I got the conditions correct, I think your results actually do show the closed limit switch is NOT opening and has the motor in locked rotor in the closing direction.

To continue to trouble shoot for a “hot motor”, thinking it is due to incorrect power,
could you make a 12VDC light that could be plugged in instead of the motor.
Are you able to raise and lower the buckets, by hand?

I think, we should be able to say the relay and wiring has the motor going in the right direction when lights are cut on/off. Thinking then the problem is the power is still being applied to run the motor. The light bulb will show that the path to ground is being opened by the limit switches when the buckets are at the correct position

IF, the switches are working correct AND your motor is getting hot due to electrical, then the internal winding insulation may be bad.

Using the OHM setting on your DVM may show the problem, just measure each of the terminals wrt chassis ground. If it shows any resistance, then current will make the motor hot without it spinning.
I said may, because some DVMs don’t have the capability to check the quality of motor insulation.
Aaahh meee. So I go back to my problem and find things have changed. Now I hear the headlight relay working. I also find that there is no longer 12V on the yellow. I put everything back in place .. held my breath and hit the headlight switch .. and I hear a slight clunk but nothing moves. Maybe the motor is toast due to overheating or maybe the limit switch is stuck closed and the motor is still trying to close the buckets but is up to the stops.

My plan is to check the voltage to the yellow wire when the key and switch are on. If it is back to 12V then the limit switch has malfunctioned. This doesn't mean that the motor is DOA but I'll see, I tested the up limit switch and it works. I also can pull the wires on the down limit switch and see if it is off or on (it should be off .. I'll see).

Why the 12V on the yellow wire with only the battery connected has vanished is beyond me .. one of the great mysteries of Pantera electrical systems. The beat goes on.
Using a DVM can some times give false readings due to its high impedance (very very little current flows through it)
so a "dirty" switch contacts have just enough continuty to SHOW 12Vs, but when a resistance load aplied, not enough current go through to run the motor.

when you saw the random numbers, that was an indication you were measuring a piece of wire that should be seperated from 12V and ground, but just enough "dirty" to cause volt readings.

Thus I think using a light bulb to replace the motor would let you KNOW when power is being applied. Now, a single bulb will not tell which way the motor would spin, however, with a couple diodes you could make a dual bulb indicator.

using a bulb and the hand crank seems like the safe way to set those limit switches
The headlight motor has no internal ground. Reversing the polarity of the motor feeds reverses the direction of the motor.
The DPDT (double pole, double throw)headlight relay reverses the polarity to raise or lower the headlights and the limit switches stop the travel.
I don't have a wiring diagram, but I think it's possible to see +12v at the motor but the limit switch interrupts the ground side, and the motor can not run.
Thanks for the input so far. River Rat, the gear was replaced several years ago. I'm going to back off the stop screw on the down limit switch and then remove it and check it for functionality. Things seem to be pointing toward that switch not opening when the buckets are down. Perhaps I can check the motor by hitting the headlight switch with the down limit switch disconnected (simulates the switch opening). The buckets should raise if the motor is not fried. Fingers crossed that it still works.

If the motor is toast someone said it can be rebuilt. It seems to be coated with a heavy duty paint. I assume the rebuilder will strip off the paint, disassemble, rebuild and repaint. But I'll be positive and say it will work as I do NOT want to go thru that contortionist act to remove and replace it.

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