Alright, guys, I haven't tried this out yet but I may have solved the mystery of the extra wire.
According to the
1954 Chevrolet Truck Wiring Diagram that I found
here , there is a 12AWG wire that runs from the third terminal down to a terminal block near the driver side head light. This terminal block has four terminals: headlight low beam, headlight high beam and parking light. My horn wire should connect to the fourth terminal.
Thing is, it looks like the horn wire was cut at some point and may not be long enough to reach. So I may have to cut and extend it to reach all the way to the terminal block. Looks like I'll be making another trip to the hardware store...
:rolleyes:
