I'd recheck your wiring against the wiring diagram. I'm using a seven wire switch, and I have to admit, it took me two tries to get it to all work happily. At first I had a short in one of the rear pigtails, so when the lightbulb was put in, it made contact with both contacts. Result: When I hit the brakes, my front park lights would come on faintly. All I can suggest, is check check recheck, and use that volt meter to see if there is a short anywhere. Take out the bulbs before you do this. Did you switch your front park light pigtails to use double filaments? I'll tell you, my truck feels pretty fancy shmancy, and my arm stays dry in the rain.
