This is what I thought:

I thought the empeg harness had a serial connection that came off of it. I thought that this serial connection provided power as well and that this was how GPS's were hooked up to the empeg for all the projects. I figured I could hook the GPS V up to the empeg using the serial data cable that came with the unit. I'm guessing i'm wrong.

The GPS is in the car most of the time, but i figured that when I needed it for Geocaching or something, I could just unplug the wire from the back of the Garmin. My intention was never to actually hard wire the GPS unit.