How to Power an Interior Truck Cap Light on a 2002 GMC Sierra 4x4

Question:

what is the best way to wire an interior light in my cap. Where do i get the power wire from.

asked by: David

Expert Reply:

You have a number of options to power an interior light on your truck bed cap. You could use the 12-volt power wire going to the trailer connector on your truck as a power source. I recommend installing a switch to turn the light on and off when needed, unless the light comes with a switch.

Another option would be to run the wire from the cap light directly to the vehicle battery. Again, I recommend installing a switch if you do not already have one, so the light does not stay on all the time.

You will simply need an appropriate length of wire, preferably the same size wire that comes with the truck cap light, and either a butt connector, # DW05714, quick splice connector, # SWC502905-1, or a ring terminal depending on how you want to connect the wire. You may also want a circuit tester, like part # PTW2993, to make sure the wiring you are splicing into has power.

If you choose to splice into the 12-volt power wire on your trailer connector and your truck has the factory trailer wiring, GM typically uses either a red or black wire for 12-volt power. I recommend testing the wires coming out of the trailer connector to find the wire that has constant power before making a connection.

expert reply by: John H