Author Topic: 1956 headlight switch assembly  (Read 228 times)

Offline Rob Leech

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  • Name: Rob Leech
1956 headlight switch assembly
« on: October 08, 2017, 06:54:15 PM »
I had to move my headlight switch out of the way to access my trunk open dash light. I have the dash pad off and after the moon and stars aligned, I finally was able to remove the shaft out of the switch by pressing the button on the back side of the switch. I think the flat side of the bar also had to be in the right position. The problem I'm having now is the shaft won't seat all the way back into the switch, it lacks about 3/4 of an inch. I have a spare switch and the shaft will go back into that one fairly easily. I am bumping into something solid in the switch. I have tried turning it in all directions and tried to tap it in as hard as I dare for fear of breaking it. Any suggestions? I really don't want to take it all the way out, it looks like a major undertaking, Thanks for any suggestions.
Rob Leech 1956 Eldorado Convertible

Online J. Gomez

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Re: 1956 headlight switch assembly
« Reply #1 on: October 08, 2017, 07:55:57 PM »
I had to move my headlight switch out of the way to access my trunk open dash light. I have the dash pad off and after the moon and stars aligned, I finally was able to remove the shaft out of the switch by pressing the button on the back side of the switch. I think the flat side of the bar also had to be in the right position. The problem I'm having now is the shaft won't seat all the way back into the switch, it lacks about 3/4 of an inch. I have a spare switch and the shaft will go back into that one fairly easily. I am bumping into something solid in the switch. I have tried turning it in all directions and tried to tap it in as hard as I dare for fear of breaking it. Any suggestions? I really don't want to take it all the way out, it looks like a major undertaking, Thanks for any suggestions.

Rob,

If you can get the shaft all the way even when you push the release bottom under the headlight switch.  :o

The only thing I can think off is the latch inside the headlight switch (the one is pushed by the bottom to release the shaft and the shaft slides inside) may have latched inside or the small spring which pushes back into the lock position is broken which will block the shaft to engage all the way in.

Sometime you can press the bottom and rotate the shaft to get it all the way back, but. ???

If all fails sorry but the alternative is to ... well you already guess it on your last sentence.  :-X

Good luck..!
J. Gomez
CLC #23082

Time is irrelevant when you work on your classic car, eventually you will enjoy it..!

Offline Rob Leech

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  • Name: Rob Leech
Re: 1956 headlight switch assembly
« Reply #2 on: October 08, 2017, 08:06:11 PM »
Thanks J. I have tried it by pushing the button and spinning the shaft. On my spare switch, it will click in without pushing the button. You have to push it to release the shaft for removal. It may be broken. Going to try a while longer before giving up. Thanks for the suggestion. Rob
Rob Leech 1956 Eldorado Convertible

Offline lexi

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Re: 1956 headlight switch assembly
« Reply #3 on: October 09, 2017, 01:11:28 AM »
If you have to disassemble the switch, place it in a ziploc bag to keep the small parts from getting lost. Just in case you had other spare parts lying around, (you did mention a "spare switch'), and you grabbed the wrong one, that could cause a problem. My '56 has fog lights which necessitated GM using a longer shaft. The non-fog light car's headlight rod will not work in the switch equipped with a fog light switching box as it would be too short. Just tossing this idea out, because I sometimes work on my car and bring out spare parts for comparison purposes to assist with the work. You can mix things up. That said, I ran into the same problem as you did and found I had to swap out the rod with a spare one from my parts. Did not study it but seems the slot cut into it just wasn't grabbing the latch plate inside. Clay/Lexi

Offline Rob Leech

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  • Name: Rob Leech
Re: 1956 headlight switch assembly
« Reply #4 on: October 12, 2017, 08:07:10 PM »
Lexi; thanks for the tip about the zip lock bag. The lock collar in the switch had moved and caused a jam. I disassembled the switch.  :(  It exploded in a dozen directions when the top came off. Still lost some parts and had to hunt for an hour to get all the pieces. I had no chance to see how it was assembled before the explosion. I had to study the switch for an hour before I was reasonably sure how it worked. Assembly is not for the faint at heart. It took hours and hours to finally line up everything at the same moment. I felt like I had assembled a ship in bottle. Everything seems to be working, getting 12V everywhere. How do you know if the dash lights are going to get brighter as you turn the knob? I am getting 12V all over the spring and everything connected to the spring, even if you rotate the point around the spring. Seems like the voltage should be changing as you dial around the spring. I cleaned and polished everything before I put it back together. Can you tell me how to check if it's going to work properly when I put the switch back in the car. All this because my trunk open light had lost its ground. A five minute fix. Thanks so much
Rob Leech 1956 Eldorado Convertible

Offline lexi

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Re: 1956 headlight switch assembly
« Reply #5 on: October 15, 2017, 07:30:23 PM »
Yes, the headlight switch will 'explode' with parts flying all over the place when disassembled, so the plastic baggie will contain the parts. I also found myself in the same rebuild situation, twice. Once more than 40 years ago and then again a year or two ago, when I had disassembled another switch, then had to relearn how to reassemble it, all over again. Takes about an hour or so. Like assembling 'a ship in a bottle' as you accurately put it. Wife learned some new cuss words. I wondered how these f&%$&@g things were put together at the factory as so much finesse is required to build them. This dash rheostat system is a weak point in these cars.

Any how, I did have problems with my rheostat (dash light dimming stopped working), and a continuity test showed that my rheostat fine gauge wire was OK, (they are usually toast) but as I recall the contacts were corroded. As I recall they are tough to see, and would be a job to tackle. Again, going from memory from a couple of years ago. Think there are some dissimilar metals there and I recall seeing a badly corroded one. Some guys totally rebuild these using a fine ohm resistance gauge wire (30 if I recall correctly), and half fill the cavity with plaster of Paris as a heat sink as well as a retainer for the replacement wire. I never went that route so I reassembled my unit and soldered a jumper between the grey wire (panel lights) and the green wire (tail lights), of the headlight switching unit, as I recall. That way the dash lights are on full strength when you put your lights on. There is no adjustment to your dash lights intensity when powered this way.

Not sure what the voltage would read across the spring between any 2 given points, (if I understand your question), but I would imagine that it should vary depending on the distance between the 2 points when measured as the coil is supposed to modify the voltage. You did not say if your panel lights work at all or not. If you are getting voltage on the rheostat coil but your panel (dash) lights are not lighting up, I suspect that the terminal at the end of the coil is toast, (as was my case). There are senior members better equipped than I to guide you through the paces of attempting a repair. But sounds like you have to (yes) disassemble the unit again, and carefully check the rheostat and it's terminals, as well as the "slider" that runs along it's surface when you rotate the headlight switch knob, making sure it makes contact. Not an electrical genius by any stretch, but I imagine that by connecting your volt meter to the PL (panel light terminal on the HL switch), with a solid ground, should reveal a fluctuating voltage when the rheostat is engaged (if working properly and with power on in the OEM wiring configuration). Below is the electrical diagram to assist. Perhaps check your connections first and keep your ziplock baggie handy! If you are still stuck, I have another switch here for back up, and could dig it out and take some photos (and perhaps refresh my memory).

Thanks to Jose Gomez for having posted this diagram in relation to an earlier thread.

Clay/Lexi
« Last Edit: October 15, 2017, 11:50:08 PM by lexi »

Offline Glen

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Re: 1956 headlight switch assembly
« Reply #6 on: October 16, 2017, 01:16:34 AM »
How do you know if the dash lights are going to get brighter as you turn the knob? I am getting 12V all over the spring and everything connected to the spring, even if you rotate the point around the spring. Seems like the voltage should be changing as you dial around the spring.

The resistance wire is just that a resistor.  To get a voltage difference there needs to be current flow.  If the lights are not in the circuit then you will get the full 12 volts at all points on the resistor coil (spring).  Use the ohms scale on your meter to check the resistor.         
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Offline lexi

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Re: 1956 headlight switch assembly
« Reply #7 on: October 16, 2017, 09:35:41 AM »
That makes sense now that you mention it!Thanks for clarifying that aspect. Brain not working as well as it used to! Clay/Lexi
« Last Edit: October 16, 2017, 09:44:33 AM by lexi »

Offline Rob Leech

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  • Name: Rob Leech
Re: 1956 headlight switch assembly
« Reply #8 on: October 17, 2017, 08:16:36 AM »
Thanks Lexi and Glen. Not knowing much about resistors, I had no idea to use the Ohm meter. I just assumed the voltage would change as I moved the point across the spring. It's not back in the car, I wanted to test everything before I reinstalled the switch. Will know more and report back in a few days. Thanks again for helping on this topic. Rob
Rob Leech 1956 Eldorado Convertible