Electrical - Wiring the Trunk
The tailights, side marker lights, reverse lights and trunk release are all part of wiring up the trunk. The taillights consist of the parking lights and brake light/signal lights. I tried to follow the GM color code for wires but didn't couldn't readily find all the colors.
You'll see in the pictures that all the sockets have a standard color code and that I changed the wire color depending on what the function was. For example, the socket brown wire is park lights, but I used a blue wire. The driver's side brake light socket wire is green but I used yellow for the driver's side and red for the passenger side. Make sure you keep track of all the colors!
I mounted a screw to each side of the trunk's chassis for the ground wires. I used an internal tooth lock washer and ring terminals to connect the ground wires (black) from each light socket to it. Being paranoid about bad grounding, I also ran a 14 gauge ground wire from each ground terminal all the way back to the firewall.
My wiring path started at the passenger side rear taillight, across the back of the trunk (there's a gutter there to hide the wiring), under the trunk latch to the driver's side taillights. Then along the rear quarter panel to the middle of the rear seat back.
Driver's side taillights before the wiring loom - ground terminal circled
Wiring running from the driver's side quarter panel to the middle of the rear seat back
In hindsight, I would be more careful about running the wires so that they don't get tangled with the mechanical trunk release cable. When I started to clean up the wires by putting the wires into the plastic split looms, there were several places where I couldn't because the wires were wrapped around the trunk release cable. Oh well, I've hid those spots well and you can't see them. Split looms have a split running down their complete side, you spread them open and insert the wires into them - quite nifty.
Split wiring looms (sometimes called cable protectors) come in many sizes and colors
Driver's side taillights cleaned up using the wiring loom
Wiring in a loom running from the driver's side quarter panel to the middle of the rear seat back
When I first started running the wires, I used a nifty self adhesive snap together cable snap that I found at a dollar store. They are supposed to be used for cleaning up the wiring in your home theatre system. They were great for the initial wiring run but are not rugged enough for use in a vehicle, too large and the adhesive didn't stick well. But they were great for the initial cable run because you could unsnap them, add another wire, snap them back together.
Dollar store cable clips
I used small tie wraps (sometimes called zip ties or cable ties) and self adhesive cable tie bases to keep the wiring looms in place. The self adhesive was industrial strength and the tie wraps were more secure than the cable clips.
Cable tie base
Cable ties