66 light switch repair

[John B.]

Hello all, i am looking for help on my light switch. I have the dash out and figured i should clean the switch. I remember seeing a nice article on this but can't remember where. I have searched. Any help would be much appreciated.

Thanks

Mike

[Ed S.]

Re: 66 light switch repair

There is a headlight switch repair how to article in the forum data base of tech articles. Look above the list of threads, you will see "Sticky" threads - there is a link to the tech article data base in it. Lots of good stuff in this list. https://www.ncrsmac.org/ed/Electrica...h%20Repair.pdf

[John B.]

Re: 66 light switch repair

Thanks ED, that article is for the switch to open the light bucket. I am looking for the actual switch that turns the lights on.

[Gary B.]

Re: 66 light switch repair

John,

There are articles in the restoration database sticky section on the repair of 1956 and 1960 headlight switches. There might be enough commonality between C1 and C2 switches for those other articles to help you.

Gary

[Ed S.]

Re: 66 light switch repair

Thanks ED, that article is for the switch to open the light bucket. I am looking for the actual switch that turns the lights on.

Ya can't win them all!

[Bill M.]

Re: 66 light switch repair

John
I took mine apart last winter the shaft got stuck in the release. it took a lot of patience to get it all back together. 64 year old fingers did not help.

[Richard M.]

Re: 66 light switch repair

EDIT: Oct 20, 2023. The following post has been digitized into a document and available here and in the Sticky DoRD Update page.

Headlight_Switch_Repair_Rev2.2.pdf

Also see This Thread for a C2 HL Switch repair process.

END OF EDIT

..........
Here's a 096 switch disassembly and reassembly process. This application is for 1958 to 1962, also a replacement for the 1963 095 switch. Later C2 versions are similar and the basic principle is the same, albeit with different terminal pin outs and rheostat switch configuration differences.


A tired and dirty 096 switch.
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Remove the knob by pushing the button on the backside while withdrawing the knob.
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Place the assembly in a vice, clamped onto the sides of the backplate. There will be 4 metal tabs on the backplate holding the housing.
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Carefully pry each one out while keeping one hand on the housing so it doesn't fall apart.
1008210813_resized.jpg

1008210813b_resized.jpg

When all 4 are released, remove it from the vice and turn it over. Carefully remove the cover, exposing the internals.
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Remove the Y shaped metal keeper for the shaft and center spring from the contact block. There is a small ball bearing under the center spring.
1008210817_Burst01_resized.jpg

Note the position of the rotating rheostat contactor assembly. Various years have different configurations but principle of operation is the same. It is used to dim(CW) or brighten(CCW) the cluster lamps. It is also used to switch the courtesy lamps on(if equipped on C1's) when rotated CCW. It does this by connecting ground of the switch metal to the lamp wiring switch circuit, typically the white wires. Take note of orientation. Remove the contactor and spring. Clean the contactor. This is what wipes against the rheostat for the dimming function. Note that if the rheostat is damaged the switch is no longer usable for the dimming function.
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Remove the center contact block. The internal terminal contacts can be seen and will need cleaning. Use a wire brush or small pieces of fine sandpaper. There is a bimetal strip circuit breaker inside also. If needed, carefully pry the contact up and clean with a very fine abrasive. Wipe any residue left over. This is the piece that reproductions did not engineer properly. It fails open circuit under lower than specified lamp current.
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There will be 2 copper U-shaped contacts and a spring under each one on the contact block. You will also see the ball floating in the housing so retrieve that for later.
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Clean the copper contacts, install the springs and contactors back in the block. Also clean the metal housing. Apply a small amount of silicone grease on to metal housing where the contactor block slides in the center.
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To reassemble the switch, hold the contactor block with copper contacts facing up and hole for the knob shaft facing left. Hold the main housing in your other hand, knob end left, upside down. Fit the contactor up and into the housing. Turn the assembly over.
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Have a roll of tape handy for this operation.
While keeping things secure, place the ball into the center hole of the contactor block, then the large spring. Place the knob lock pawl over the block as shown. Install the rotating assembly into the rheostat center hole. Hold the metal housing cover over the front of the rotating assembly, then rearward over the main switch housing.
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Before bending the 4 metal tabs over the housing nubs, wrap some tape around the switch to hold it together.
Install the knob into the switch and check operation. Also check for proper operation of the rotating rheostat actuator to see the copper contact connection. The entire switch function should now be much smoother after cleaning and lubrication.

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Finally carefully push the 4 metal lock tabs over the housing nubs. Done.

=======

Additional information.
Here you can see the rotating rheostat actuator in both positions. A protrusion on the part pushes on the contactor and closes the circuit using the ground from the rotating metal portion. This function changed over time, likely due to failures and cost/complexity.
1008210852a_resized.jpg 1008210852b_resized.jpg


Here is another configuration of the rheostat actuator and contactor. This one simply pushes the copper contact on to the metal housing.
1008210902_Burst01_resized.jpg 1008210902_resized.jpg 1008210902a_resized.jpg 1008210902b_resized.jpg

In general, it is best to try to repair these original switches. Detailed restoration would include re-plating of metal parts. This process was to simply get this one to function again.

Rich

Edit: Added 2 diagrams for test and diagnosis reference.

Switch function table
1959_HL_SwitchTableR2.jpg

1959 wiring diagram harness notes.
1959_HL_SwitchHarnessWiring.jpg

[Mike M.]

Re: 66 light switch repair

a good generic 1965 headlight switch is available from STANDARD their part # DS 155. dont accept any other manufacturers switch. the STANDARD switch cost less than 20 frogskins, fit perfect and function like the OE. note. there has to be a good ground between the switch and the cluster as well as the cluster ( the ground wire that high up on the back of the cluster). if there is no ground between switch and cluster, the dimming function as well as turning the courtesy lights and dome light will not work without good ground. mike

[Bob W.]

Re: 66 light switch repair

I agree with Mike the Standard switch works just like a OE. switch.

[John B.]

Re: 66 light switch repair

Thanks Gary.

[John B.]

Re: 66 light switch repair

Thanks Richard. Pictures are awesome!

[John B.]

Re: 66 light switch repair

Thanks Mike. I will buy that one if mine stops working.

[Richard M.]

Re: 66 light switch repair

Ed Szeliga is working on a PDF conversion of my repair post. When we have it completed I'll add it to the Sticky.

If anyone has photos of the later C2 and C3 switches I'd also like to add them into the article.

I may also add a chart of GM part numbers for reference, but away from my books at this time.

Rich

[Gary B.]

Re: 66 light switch repair

I agree with Mike the Standard switch works just like a OE. switch.

Mike, Bob,

Would the Standard switch also pass judging, cosmetically?

Gary

[Leif A.]

Re: 66 light switch repair

Gary,
I don't see where the switch, itself, is a judged item.