i can't remember exactly which one is which as i just experimented until i got the right combo...one wire is pos, one is neg and the other is back lighting for the white dots on the switches to go to an illumination wire...i went to the headlight switch for that wire. i actually just had a couple wires that were known ground and power and tried a few different combinations until i could press a homelink button and got a red light. i'm sure one could use a test light to figure it out too.
Pat