Switch rating 101. Low volts (6) equal high current to do same work. High volts (12) equal less current to do same work. Dimmer is a resistor. To dim dash lights add resistance to the circuit. Here is where we get confused. In the best of all possible worlds you would keep the switch contacts from a 6 volt for all applications. Enough current for 6 volts and a good long, as in forever, life at 12 volts. The resistor to dim the dash lights would be matched for 6 or 12 volts. Bigger resistor for 12 volts and smaller resistor for 6 volts. So I suspect the manufactures, and this just my own suspicion, make one switch with different resistors for either 6 or 12 volts. I would expect the same for Heater controls as well. And like truckernix I don't dim my dash lights either. Any one take one apart to see if they are different?
