Non Dimming headlight switch - Chevelle Tech
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post #1 of 8 (permalink) Old May 12th, 18, 12:11 PM Thread Starter
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Bob
 
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Non Dimming headlight switch

Hello all . . . . 1969 Chevelle Malibu. Replaced the headlight switch with a "Ground Up" switch because the replacement switch already installed by others, before I purchased the car, would not dim. Same problem, will not dim the dash lights. Wiring plug all ok.
Thoughts?
TIA
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post #2 of 8 (permalink) Old May 12th, 18, 1:01 PM
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Joe
 
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Re: Non Dimming headlight switch

Does the dash have stock style incandescent bulbs or has it been converted to LED dash lights?

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post #3 of 8 (permalink) Old May 12th, 18, 1:23 PM Thread Starter
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Bob
 
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Re: Non Dimming headlight switch

Still stock bulbs.

Last edited by CTHawk; May 12th, 18 at 1:24 PM. Reason: added wording
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post #4 of 8 (permalink) Old May 13th, 18, 5:21 PM
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Re: Non Dimming headlight switch

Joe, is the variable resistor on the power or ground side?

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post #5 of 8 (permalink) Old May 13th, 18, 6:03 PM
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Re: Non Dimming headlight switch

Remove the headlight switch. Use an ohm meter between terminals 2 and 3 of the headlight switch. Turn the dimmer knob, if the resistance changes the dimmer function is good and someone probably hooked up the instrument lights incorrectly by hooking into a regular powered light circuit.

Since you have the old switch out of the car, test that. If it works properly you can come to the conclusion that somebody tied into the incorrect circuit or the instrument circuit has come into contact with a regular unresisted light circuit.

The resistor is in the power circuit.

This video walks you through the headlight switch test procedure.
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post #6 of 8 (permalink) Old May 13th, 18, 7:34 PM
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Joe
 
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Re: Non Dimming headlight switch

Bob,

Use the "sticky" I wrote as a guide for the wiring placements on the switch. Of course, you won't have a purple wire...

https://www.chevelles.com/forums/27-e...photos%7D.html

The green wire is the rheostat output to the dash lamps fuse in the fuse block.

If the switch is built correctly, there is an off position. In the "dimmest" setting, the wiper actually goes up over the ceramic area onto it's own connection, thereby disconnecting from the rheostat spring. This completely turns off all the dash lamps. If can't even "turn off" your dash lamps, there is some sort of wiring issue or switch issue.

Use this photo as a guide. This switch's dimmer is in the "off" aka "parade mode" where the dash lights would be completely extinguished:


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post #7 of 8 (permalink) Old May 14th, 18, 12:18 AM
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Re: Non Dimming headlight switch

The rheostat test I described in post 5 begins at time mark 6:28 in the video.
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post #8 of 8 (permalink) Old May 14th, 18, 12:23 AM
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Re: Non Dimming headlight switch

Quote:
Originally Posted by Coppertop View Post
Bob,

If the switch is built correctly, there is an off position. In the "dimmest" setting, the wiper actually goes up over the ceramic area onto it's own connection, thereby disconnecting from the rheostat spring. This completely turns off all the dash lamps. If can't even "turn off" your dash lamps, there is some sort of wiring issue or switch issue.
^^^^^THIS RIGHT HERE.
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