# Automotive Truck light wiring HELP



## mitch95100 (Aug 14, 2013)

Im not sure about the whole wiring thing so im hoping for some help!!
Ok so I have a 1992 GMC 3500 1 ton dually pick-up that has marker lights along the bottom of the running boards, they run to a lighted switch inside that has 3 prongs Ground, Acc On, and power in. So when all is hooked up I get nothing to the lights and the switch doesn't light up. But when I connect the live wire to the power in and the other to the ground and nothing connected to the acc on, I get the lights when the switch is off and no lights when its on. Im stumped. Any suggestions?m Ive already tried another switch and it does the same thing.
And I probably not making any sense but bear with me.


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## promac850 (Aug 14, 2013)

Move the wire on the ground terminal to the acc on terminal.

The ground terminal is for lighting up the switch, not operating the accessory you're wiring in.


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## mitch95100 (Aug 15, 2013)

promac850 said:


> Move the wire on the ground terminal to the acc on terminal.
> 
> The ground terminal is for lighting up the switch, not operating the accessory you're wiring in.



I understand that much, i had ran a ground to the switch and didnt seem to affect it at all. Unless my ground wasnt good enough...

Sent from me to you using my fingers


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## promac850 (Aug 15, 2013)

Alright, so the switch has its light ground... is the running board light system grounded to the frame? If it isn't... try that.

If the switch doesn't light up when you flip it to "ON" then that ground on the switch is poorly connected.

The ground on the switch is not for the running board lights.

Otherwise, I'm not sure what else could be ****** this up until I know where the terminals on the switch are, and where the toggle is in relation to that when it's on and off.

Which terminal is on top, in the middle, and on the bottom? Where is the switch when it's off, up or down?


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## LegDeLimber (Aug 15, 2013)

You'll need a test light to verify good ground and power connections.
A multi-tester wont load a circuit and you can think your getting power
but a resistance will prevent it from feeding a load though ( I learned this firsthand)

If my brain is right this morning:

You need to bring your positive supply to the "power in"
(using a fused circuit is an absolute must) 

The ground terminal is *only* to supply a circuit for the light in the switch .

The accs terminal will feed to the actual load/running lights.
the running lights need to be grounded back to the chassis to complete the circuit.

I would strongly recommend using a ground wire screwed to the board lights 
and then run to a solid spot under the hood or grounding point of the existing wiring.

road grime ,salt, soap etc tend to erode your ground path if you just leave it to
find it's way back through the various parts till it reaches the charging system.


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