Control unit, ventilation fan, ACC (220b): Connection

The fan control unit contains two connectors; a four-pin connector connected to the ACC unit and a two-pin connector which is directly-connected to the ventilation fan motor.

Four pin connector.

B+ feed to control unit pin 4 from fuse 23 (fuse board 22) and is connected to ground through pin 1 on grounding point G41.

Fan speed is controlled from ACC unit pin 5 (K32) through control unit pin 3 with a 2 kHz PWM.

Fan control unit pin 2 is connected to ACC unit pin 25 (K32) with a return feed for diagnostics information. The control unit sends a 2 kHz PWM to the corresponding fan speed input. If a fault is detected, the control unit sends the indicated pulse ratio and the ACC unit generates the relevant DTC.

Two-pin connection to the ventilation fan motor.

The control unit is mounted in such a way that its two-pin voltage and ground connector are directly connected to the ventilation fan motor.

The fan motor is connected to ground through the fan control unit on grounding point G41. Fan motor speed is controlled by the control unit with an increase or decrease of the power supply.

Fig 1: Identifying Communication Flow - Ventilation Fan Control Unit (ACC)

Courtesy of SAAB-SCANIA OF AMERICA, INC.

Wiring diagram, control signal.

Fig 2: Circuit Diagram - Ventilation Fan Control Unit (ACC) (Control System)

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Wiring diagram, power supply.

Fig 3: Circuit Diagram - Ventilation Fan Control Unit (ACC) (Power Supply)

Courtesy of SAAB-SCANIA OF AMERICA, INC.