There are 2 kinds of switches being used on D4C. . . So, it depends on which switch type you have:
If you have the kind with 6 terminals (3 terminals on each side of the switch), then the power cord wiring goes 1 wire to the ISOLATED terminal on one side of the switch, and 1 wire to other ISOLATED terminal on other side of switch. The remaining 4 wires then get split the same way . . . 2 motor field wires go on opposite sides (from each other) of switch . . . and the 2 power nozzle receptacle wires wires go on opposite sides (from each other) of switch. Among the 6 wires, each 2 wire pair (power cord, motor, and power nozzle receptacle) MUST be separated so as to be wired to opposite sides of the switch. If you ever install both wires (from the power cord, the motor, or the power nozzle) together on the same side of the switch, you will do electrical damage to your machine, as that will connect hot and neutral wires together.
eagle77w, October 2009
