57 Headlight switch / rheostat

[57eldoking]

Trying to get some dash lights back in my Seville. Searching thru earlier threads led me to the headlight switch which I have now dug out and discovered the last two coils on the rheostat have burned off.

I read in previous threads that the rheostat can be bypassed by soldering a jumper wire which will leave the dash lights bright. This may be obvious but can someone point out where I should solder this jumper wire?

Thanks!

[J. Gomez]

Henning,

The Grey wire is for your instrument lights, disconnect it from the headlight switch (label P.L.) and connected it to the Dark Green for the dashboard lights at the headlight switch (label T.).

Good luck..!

[Walter Youshock]

You can also try soldering a wire across the broken section of the rheostat.   It will give some dimming function.   I replaced my rheostat with one from a Buick if I recall. 

[Coupe Deville]

Every Cadillac headlight switch I have ever pulled out had a busted rheostat. If the gap is small enough across you can do what Walter said. Works fine, done it many times.

-Gavin

[57eldoking]

I thought the coil would heat up from the resistance and "melt" the solder, guess I haven't got much to lose by trying though 

[Coupe Deville]

Shouldn't melt the solder. I soldered that same exact spot on my 57's switch.

[J. Gomez]

The biggest issue with all of the rheostats type dimming switches is; 

The bulbs would need to be the correct ones. Changes on these would increased (or decrease depending on the type of bulb used) the amount of current and thus creating more heat on the resistance wire.

All bulbs would need to be working else back to above statement on increasing the current.

Friction and age also plays a big factor, the brass wiper rubbing against the resistance wire tends to deteriorate them. Some electrical grease should help, however age would eventually take over.

Placing a glob of solder does works but there are two problems;

One the resistance of the wire would be less depending on the number of patches, so once you pass the patched areas the wire would get hotter. It may not melt the solder (eventually) but it would degrade the rheostat resistance wire.

If the patch is not smooth going over them with the brass wiper will rubbed off the soft solder. Soldering them should be fine if you are not going to dim the lights regularly beyond the repair area.

I’ve rebuild several of these and all had the wire open on the surface usually at the same area as Henning’s picture or about ¼ turn from the tip ”full on” position.

[57eldoking]

What I don't understand is: Shouldn't the dash lights come on once the brass wiper is moved past the break in the coil and brought into contact with the right side terminal? I would have thought this would complete the circuit and turn the lights on at full brightness.

[J. Gomez]

Henning,

It should..!

The brass wiper slides in a brass collar inside the rheostat this collar is connected on the left side dimple (your top picture) this make contact with a brass tap at the switch on the other side of the rheostat (your bottom picture).

Corrosion may cause the contact not to make properly once you turn the knob to that position.

You need to check these areas for continuity.

I’m attaching a picture of one of the rheostat I worked that shows front collar and rear contacts.

[57eldoking]

Excellent explanation Mr Gomez, thank you! I'll try to take it apart tomorrow and report back. Any tips on disassembly?

[J. Gomez]

Tips sure don’t do it..! 

The switch itself has a spring loaded bar with to brass cups at each end, these slides inside when you pull/push the headlight switch. Once you removed the 4 or two screws from the bottom plate, just be careful they tend to fly all over. 

Second placing the rheostat back is a bit tricky, sliding in both top and bottom groves while holding the rheostat wiper and the spring and the washer and the insulator..! Augh..! 

Last but not least make sure the triangle brass contact inside the headlight switch is place correctly, else you will have to do it all over again. 

Good luck..!

[Walter Youshock]

Think of it like the sending unit in the tank
  Same principle.   And the switch is a bitch to disassemble and resemble.   I removed the screws,  held it together and put it in a clear plastic bag so the springs didn't go flying all over.

[J. Gomez]

held it together and put it in a clear plastic bag so the springs didn't go flying all over.

Walter,

Bingo... and those babies sure fly all over..! 

[56 Eldorado]

Hi Jose,

I also am having trouble with the dash lights on my 56.  What is the trick to removing the light switch from the dash?

Thanks,
Tom Modaff
CLC#26179

[Walter Youshock]

It's a bit tricky.  Either remove the cluster so you can see the switch and wiring.  I'd suggest this method because installation will also be easier.

On the top of the switch, you'll find a spring loaded knob.  Pull the switch fully out as you would to turn on the headlights.  Push that knob down and pull the headlight switch.   It should release the rod and expose a spanner nut holding the escutcheon.   Remove that and the switch is out.

If you have fog lamps, you have to gently pry the fog lamp switch off before seeing the spanner.

[57eldoking]

Just finished the repair, glad I followed Walter's tip and opened the switch inside a plastic bag! I was almost regretting opening the switch to begin with as the internals went all over the place! I was however successful in piecing it back together without too much difficulty. I put down a blob of solder over the broken rheostat section and sanded it down so the wiper would contour over it nicely.
One of the leads on the backside of the rheostat was also badly corroded, sanded this down and got good continuity all through the rheostat now. Looking forward to installing it this weekend  Next job is the instrument cluster, the speedometer is not working but the odometer is so hopefully it will be fixable.

   

[Walter Youshock]

Good job!

[J. Gomez]

 Ditto...! 

[Walter Youshock]

I just noticed you also have an '82 Fleetwood brougham.   I had one.  I loved it.   It was the best Cadillac I ever owned, outside of the exploding engine.  Mine was a Sheffield gray fire mist d'elegance with gray cloth.  23.5 mpg on the highway fully loaded.

Other than the '57,  it was the only other Clark built car I had.  I'm sorry now I drove it into the ground.

[57eldoking]

I loved mine too, sadly I sold it a month ago . The HT4100 served me over 20.000 problem free miles in the last two years!

Here she is a couple of weeks after I bought her, drove it across the country to Baltimore and shipped her home to Norway after this picture was taken. That was a GREAT trip