Anyone who had an old body style (GMT 800) and used the cargo light switch probably misses it, like I do, in the new body style (GMT 0900). I use the cargo lights A LOT when hauling things and/or towing to check loads etc. You can't see anything in the bed form inside the cab in the NBS trucks as the dome lights are on as well. So, I decided to add my own dedicated switch. I figured I'd share and do a quick write-up for anyone that wants to do it as well. I chose to put the switch in the overhead, you might find a better place for you.

Tools Needed
T-15 Torx driver
7mm nut driver (or ratchet and socket)
Wire Cutters
Crimpers
Wire puller
Trim Pry Tool (or Flat Blade Screwdriver) something like this http://www.eastwoodco.com/shopping/product/detailmain.jsp?itemType=PRODUCT&RS=1&itemID=2635&keyword=52298&cm_mmc=undefined
Electrical Tape
Multimeter
13/16 Drill bit (I used a 7/8 UniBit and stopped at the 13/16 step)Parts
1 x Lighted Rocker Switch (Radio Shack 275-0020 is what I used)
3 x 3/16 Female Spade Connectors
Wire ( I used 16ga white, red and black, but any colors will do)
1 x Fusible linkProcedure
Remove A-pillar cover
Pop out the small screw cover, using 7mm nut driver remove retaining screw then pull cover away from a pillar.http://www.sogracing.com/cargolight/topapillar.jpg
You can simply pull the top portion out enough to work or using the pry tool also pry the bottom of the a-pillar cover up to remove it. If you have the speaker you will have to un-plug it as well.http://www.sogracing.com/cargolight/bottomapillar.jpg
Disassemble overhead controls.
Using pry tool pop out the dome light cover.
Using T-15 torx driver remove 2 screws next to dome light bulbs.
The rear of the overhead has 2 trim tabs on each side. Grab the overhead towards the rear and pull straight down on each side.
Unplug the overhead wire loom.
Install switch
Drill 13/16 hole for the switch and install the switch into overhead console.http://www.sogracing.com/cargolight/switchhole.jpghttp://www.sogracing.com/cargolight/switchinstalled.jpg
Run wires
Using a wire puller (I used the “Chinese fingers” type) run 2 wires from the overhead console location over to the a-pillar.
Leave 1 wire about ˝ way down the a-pillar. This will be used to splice into the cargo light circuit.
The second wire should continue down the a-pillar, under the dash, and back up to the fuse box. This will be used to supply the +12V for the cargo lights and the switch.http://www.sogracing.com/cargolight/fingers.jpg
Locate and splice cargo light wire.
Running down the a-pillar, in a plastic “sleeve” is a cluster of wires. Using the multimeter locate the white wire with black tracer/stripe that shows +12V when the cargo lights are on and 0V when the cargo lights are off. Note there are two white/black wires so you have to test to find the right one.
The wire you just found is the wire that you will splice into and apply +12V from your new switch. I chose to cut the wire and use crimp connectors to splice the white wire into the circuit.http://www.sogracing.com/cargolight/lightwirecut.jpghttp://www.sogracing.com/cargolight/lightwirespliced.jpg
Find +12V source
Using the fusible link tap into a +12V source. I chose to get +12V from one of the body controller connectors inside the fuse box. I strongly suggest using a fusable link when doing this or you run the risk of ruining the circuit or worst case causing a fire. I tested a 2, 5 and 10Amp fuse and ended up with the 10Amp, which is what the dome lights are on stock as well.http://www.sogracing.com/cargolight/12vsource.jpg
Locate and splice ground.
In the overhead console wire loom is a 16ga Black wire which is constant ground. This is what I used to provide ground for the rocker switch light. I chose to cut the wire and use a crimp connector for the splice.http://www.sogracing.com/cargolight/ground.jpg
Wire Switch
Attach 3/16 female spade connectors to each of the wires you have added at the overhead console. (+12V, cargo light circuit and ground)
Attach the ground to the male spade which reads +/-. This spade is gold.
Attach the cargo light circuit wire to the middle male spade.
Attach the +12v to the remaining male spade.http://www.sogracing.com/cargolight/switchwired.jpg
Put everything back together and you have a dedicated cargo light switch.http://www.sogracing.com/cargolight/FinsihedOn.jpg

Very nice looking job and good details. May be my next mod.

Brian

Nice job, something I will do. Now, how about a indicator light (LED) for the 4wd? The little light on the switch is not in plain view and barely noticeable.

That would be a nice idea for 4 wheel. I have a few times turned it to 4 low while driving. Luckily it wont goto it at high rate of speed. The knob is a dumb idea on the NBS.

Brian