light switch

[dlcoop]

Any good electricians here. Trying to troubleshoot my headlight switch before I spend money on another one.  I removed the switch and cleaned as best I could.  Headlights etc all work.  Just can't get the instruments to work.  I have power at the gray wire but no lights are coming on.  (have the dash out right now to replace all bulbs with new).  A grounding issue maybe.  Even used switches are very expensive.  

[rocketraider]

Year and model?

 

Most GM vehicles by the 1960s have an instrument panel lamps fuse that feeds off the headlight switch. See if there's one in your fuse block.

[dlcoop]

my fault.  1955 super.  No fuse on the switch nor a fuse in the fuse block.

[usnavystgc]

Do you have power at any of the bulbs?

[dlcoop]

Negative. Only headlights and parking lights.

[usnavystgc]

I mean have you checked for 12V at the input to the light bulbs at the socket?

 

[usnavystgc]

I'm not trying to be too elementary but, did you read this from the shop manual and is that switch not in the full ccw position?

This would make sense since you said the place where the map light control is on my car has a blanking plate there.  It looks like your headlight switch controls that instead.

Edited April 27, 2022 by usnavystgc (see edit history)

[dlcoop]

I hadn't read the manual yet.  I always thought that as you turn the know clockwise, the lights would dim of be off.  Full counterclockwise (to my left)  would turn on the map light etc... Will double check later.

[KAD36]

Correct - Full left everything should be on. Last 1/4 inch or so the lights go out and only map light over radio is on, then full left all on per the excerpt.  How clean are contacts and rheostat on switch?  Going off memory and a quick look at schematics there is an 18ga yellow wire that comes off the foot dimmer switch and feeds the rheostat, then off the rheostat an 18 ga white feeds the instruments and an 18ga black feeds map light which is an on/off.  Pull up the schematics and validate.  Seems the yellow wire is a common single point failure to checkout with a voltmeter or test lamp, assuming switch is good.

[dlcoop]

I am beginning to think I am jinxed.  I messed with the switch a couple of nights ago.  I had changed all the bulbs.  Now all of a sudden  everything started working.  All instrument lights are good.  Mu only issue now is my dome light will not turn (except by the switch)  when the doors close.  I replaced both jam switches also. Maybe next week it will start working like it should.  Thx to all for all the input. 

[KAD36]

You must have intimidated it back into operation.  One less upside down trip under the dashboard (groan).

 

Well done glad it works!

 

Check for good ground at jamb switch.  Mind where the paint is to not insulate it.

Edited May 4, 2022 by KAD36 (see edit history)

[d2_willys]

Check the switch at the light or between the left front door and left rear door. In the door jam/headlight switch instrument panel position the slide switch contacts are probably dirty. Wiggle the switch handle while a door is open.

[Beemon]

I'm pretty sure the dash lights are wired in series and grounded through the socket. If one loses ground on the branch (or a bad bulb) then the whole branch goes out. I am currently facing this issue on my 56 and have been practicing my Egyptian hieroglyphics. 

[JohnD1956]

46 minutes ago, Beemon said:

I'm pretty sure the dash lights are wired in series and grounded through the socket. If one loses ground on the branch (or a bad bulb) then the whole branch goes out. I am currently facing this issue on my 56 and have been practicing my Egyptian hieroglyphics. 

That should not be the case. Each socket provides it's own ground and each bulb works independently.  The radio light works independent of the instrument lights but the clock and heater controls work with the instrument lights.