Blower Ground-Side Switching Circuit Test

NOTE: Voltage readings, on the blower circuit of the ground-side switching circuits, decrease instead of increasing as the blower motor speed is increased.

A/C-Heater System Electrical Wiring Diagram And Continuity Test:

Circuit 261 (O/BK) will always read the same voltage as battery positive (+) voltage and the circuit 57 (BK) 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 (-) circuit 57 (BK) directly to ground.