Blower Ground-Side Switching Test

Amperage readings, on the blower motor circuit, will increase as the blower speed is increased. This is the same as on previous supply switching circuits of previous model vehicles.

ATC System Electrical Wiring Diagram And Continuity Test:

Voltage readings, on the blower circuit of the ground side switching circuits, decrease instead of increasing as the blower motor speed is increased. The orange-black 261 circuit will always read the same voltage as battery positive (+) voltage and the black 57 circuit voltage will decrease with each increase in blower speed. A maximum blower speed switch position will produce a zero voltage reading as a result of the blower speed switch bypassing the resistor assembly and connecting the blower's negative (-) black 57 circuit directly to ground.