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Old August 10th, 2022, 10:08 PM
Scrapcan Scrapcan is offline
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Join Date: Apr 2022
Location: Burns, WY
Truck: 1963 GMC 2500 dump bed
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Default Re: headlight switch wiring for 1963

I have ordered the wiring diagram and waiting on delivery. a nice hard copy in hand is handy when working on this instead of digital file. until it gets here I am asking for help from the forum, and I appreciate all the help I am getting.

Here is a picture of the old switch I put pin numbers on, new switch looks the same other than no issues as the old switch. old switch had been apart before with problems.

pin 1 is white(natural?) and is front markers through the front-left firewall connector

pin 2 is light blue and is dimmer for headlamps

pin 3 is white (natural?) is dome light (is this the ground side of dome light circuit?)

Pin 4 I need to verify the color but think it is red and 12v+ unswitched from the front-left firewall connector

Pin 5a is black and is rear tail lights through the center-firewall connector

pin 5b open no wire connection

pin 6 is orange, double wire to connection, not sure but I think this is 12v+ to the fuse panel and to the stop lamps switch.

pin 7 is dark green and is instrument lamps through fuse panel?

with switch in rest position ( all the way in) 12v+ on pin 4 and pin 6. front and rear turn signals and brake lights work

turn switch to dome light position and puts 12v+ power on pin 3 and power at dome light fixture. turn signals front and rear and brake lights work

with switch in position one ( pulled out to first detent, have power to pin1, pin5 ( a and b on old switch, need to test new switch), and pin 3 if in the dome side of switch. tails on, markers on, instruments lamps on and dimmer works for instrument lamps. turn signals front and rear and brake lights also work.

with switch in position 2 ( pulled out to activate headlights. have headlights both dim and bright. no tails, no markers, and no instrument lights. Have the power to dome light if switch turned to that position. Turn signals front and rear and brake lights work. Need to test power to 5(b) and pin 7 on new switch.

the old switch had a bar between pin 5(a) and 5(b) so with the switch in either position and switch in position 1 or 2 ( tails and markers position 1 or headlights position 2) the slider will have power to pin5(a) and 5(b). this would make tails work in both switch positions. Pin 7 is also fed power on the connector bar from 5(a) and 5(b) on the old switch thus powering to instrument lamps.

the old switch also disconnected pin1, as discussed on Jolly's site and as designed, when the switch is pulled out to position 2 (headlights on). need to test this on the new switch

as noted above, I will check the new switch again tonight for continuity in the different positions
Attached Images
File Type: jpg HDLS-pinout.jpg (1.73 MB, Multiple views, 5 clicks)

Last edited by Scrapcan; August 10th, 2022 at 10:22 PM.
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