The headlight motor is too hot to touch

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)?
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)

Matthias
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.

Rocky
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.
The motor case does not serve as a grounding connection, nor is it designed to carry any current at all.

There are two wires entering the motor, neither of which show continuity to the motor case.

Through the various relays and limit switches the polarity of the two motor wires is changed. A polarity change on a DC motor changes the direction of rotation for that motor.

Near the center of the diagram, BK denotes the grounding connection for the relays and for the motor.

Larry

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So here is the deal. Ignition switch works, dash headlight switch works, limit switches work, battery is charged, relay "clicks" but I'm not sure if that is a sign of working, .. the motor .. nada, zip, nothing .. no sound, no movement, no heating up even with the headlight switch on. It looks like I need to remove the motor (ugh) and test it. I may have a source of another one. Question: the headlight relay from Wilkinson is about $190 .. does anyone know of a less expensive alternative?
during the last checks, have you used the handwheel to position the buckets. the reason I asked, I am ASSUMING the motor is bush design and that maybe you burnt one of the commutator's teeth and by manually spinning it to a new tooth would allow it to start.

another test would be check the two leads of the motor for continuaty with the Ohm setting on your DVM. I checked my motor (that had't been spun in decades) and it showed 15 Ohms. after spinning it a little, the DVM became a "random Number generator Smiler " and showed about 20 to 30 ohms. A reading of infinity would indicate burnt away brush or tooth
The relay is just a dpdt 12v coil relay. This one is rated at 30 amps and sells for around $10.00 or so at ebay or amazon or many other places. You may need to add a jumper from one contact to the ground.


JQX-12F-2Z-DC-12V-30A-DPDT-General-Purpose-Power-Relay-8-Pin-LW-SZUS

Forest
Another update. I pulled the motor/gear assembly and bench tested. It works just as designed. So my search continues. I tested the two limit switches. They show open normally and a small continuity resistance when clicked (closed) I always thought they opened when clicked .. but just the opposite. This now leaves the relay, the dash switch and the ignition switch as suspects.

Question: should the headlights come on when the headlight switch is fully turned on even with the ignition switch completely OFF? Mine do. I can see why the parking lights would come on but the headlights? If the answer is no then that might be a hint as to my problems. I'm looking more and more at the relay. The beat goes on.
Not sure I sure i want to admit my experiance today.

I tested my two switches and got your results...I was confussed, how could the circuit work. I was even using my high dollar Fluke.

This worried me all afternoon, coming back from an errand, I decide to verify. this time using a Radio Shack that I abused that was in trailer.

First check...same as yours. checked my meter auto setings, tested my leads for open/closed.

THEN, i got the expected
normally closed,
open when pressed.

I am sure I repeated this several time.

Maybe it was a meter setting

BTW...I quit work years ago when I was getting confussed alot

edit...
took a couple photos since I can forget....

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I played with my lights a little - not sure if this will help:

PS. When I say "Light Switch ON" I mean two detents - i.e. Headlights, not just parking lights. I also get two lights on in the instrumentation - one on the tach, and one on the speedo.


1. Ignition OFF / Light Switch ON: Parking lights are on - Headlights are down and ON, even thought the buckets are retracted.

2. Ignition ON / Light Switch ON: Headlights come up and the lights are ON as the bulbs are coming up.

3. Ignition ON / Light Switch OFF: Headlights OFF as soon as the switch goes to OFF, and then the lights retract.

4. Light switch OFF, then Ignition OFF (during retraction): Headlights freeze when the ignition switch is shut off.


Rocky
JFB .. I'm no electrical genius .. just the opposite. I think that the limit switches are suppose to connect when clicked and open when unclicked. I think that the limit switch tells the relay to stop or start powering the motor. The motor circuit is not directly interrupted by the limit switch. There is a lot of current operating the motor and the limit switches seem much to fragile to accommodate 30 amps or whatever they draw. But I could be wrong. Smiler

I may replace the limit switches just because of their age but I really think the relay is the culprit.

Rocky, thanks for the light tests .. very informative. For those with high powered headlights, if they were going to just park and hit the parking lights but accidentally pushed the rocker switch to the second position, those retracted headlights are going to fry the bucket covers. Very odd design.

I sense a headlight at the end of the tunnel.
I still recomend making a lamp to plug into the motor's two connectors to help you see what is going on without the chance of damaging the motor.

Using aux relays to reduce the current through the switches is possible, but have you seen those two realys somewhere. Also, with out making a logic diagram to verify, using normally open for aux relays would mean those two relays need to be hot when the motor is NOT running....not a good design.

Redoing the factory wiring so that the headlights do not light until the buckets are opening was on my wish list
My headlight issue is approaching a finale. While under the passenger's side dash looking for the proper relay (pre-L location) I found that the relay panel is secured by two wing nuts and can be dropped down for better access (a discovery for me). Protruding down from that panel is a long(4 or 5 inches)threaded rod also with a wing nut but it does not secure anything .. it's just there. Question: is there suppose to be a panel or kick plate that that long rod secures? What is it's purpose. I've owned 3518 since Jan. 1973 and have never removed anything down there (that I can recall .. but I'm older).
WOW ... I certainly would have remembered that component. I bought the car from a Porsche dealer and there was one owner before me, and then only for a few months. I wonder where that damn thing went? I suppose those are NLA. Thanks for the info.
There should be plenty available as many have redone their wiring (including me) and did away with that whole set of relays. I probably have it around here somewhere as I don't throw any Pantera parts away. ZONKEY is an early car (1549) and it's possible it's a different size. I seem to remember that the holes are a lot smaller.
I should probably measure the relay panel to get an idea of how big that missing perforated cover should be. My car is 3518 so I don't know where that sits in the pantheon of relay covers. I've got my checkbook at the ready if someone has a spare.
My headlight issue is no longer. After removing and checking out all the electrical and mechanical components of the headlight system, I reassembled and TAA DAA .. it works as designed. No repair/replacement of any parts. The only expense is bandages for the fingers and arm cuts from working in tight quarters with sharp edges.

The questions now are: why did it happen and how did it go away? As best as I can figure there was binding between the small drive gear and the sector gear on the headlight bucket shaft. The motor mounting plate is slotted for positioning. Gear engagement is critical. When I reworked things 3 years ago I didn't run the lights up and down manually to verify proper gear engagement .. I did this time.

So it works and the above is the best explanation I can come up with. The motor overheating was due to having to work very hard to raise the buckets. If its not that .. I got nothing. But it WORKS

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