I tore into the electrical system for my son's new '55 1st GMC today. Surprise!!! It has two 6 volt batteries. They are wired in series providing 12 volts to the starter, head/tail lights, alternator, and ignition system. The system is then half tapped (only one of the batteries used)to provide 6 volts to the cab, dash, instruments and heater. :rolleyes: I mean, this is really clever stuff, and I can't think of any theoretical reason it shouldn't work just fine. I expect its going to take me a full day to modify the standard wiring diagram to reflect the changes though -- and to confirm that he did it right.

It seems to work very well. Everything seems to operate just fine with the sole exception of the horn (any wire having anything to do with the horn is swinging in the breeze). Maybe he got that far and was finally stumped.

Has anyone ever done this before? Has anyone ever HEARD of this before? Can anybody think of any reason I shouldn't just finish the horn and leave it alone?

adrift in the Great Salt Lake
jerry