Blower Motor Wiring Diagram [top] | Freightliner M2

Connected to a chassis grounding point; the wire is usually black. Pin 4 (Power): 12.6V constant power from the 30A fuse in the PDM. Pin 6 (Speed Control):

Receives a variable signal from the HVAC controller to set fan speed. Freightliner M2 Blower Motor Wiring Diagram