Basic Function Of All-Wheel Drive Control Unit - GF28.19-P-9891A

MODEL ALL (CAR) 

Shown on model 177.0 

Overview 

This document contains the following information:

• Location 
• Task 

Location 

The all-wheel drive control unit is located on the left in the trunk.

Task 

The all-wheel drive control unit actuates the all-wheel drive actuator motor in the locking differential drive unit according to the driving situation.

When the multiplate clutch in the rear axle differential is actuated by the all-wheel drive actuator motor, the drive torque is distributed from the front axle to the rear axle. Up to 50 % of the drive torque can be passed onto the rear axle.

Wear data of the rear axle differential is stored in the all-wheel drive control unit. If the control unit is replaced, the data must be stored in the new control unit.

If the oil or the entire rear axle differential is replaced, the wear data must be reset.

The temperature in the rear axle differential is calculated in the all-wheel drive control unit. Input factors are the ambient temperature and the position of the all-wheel drive actuator motor.

The instrument cluster outputs the following messages in the event of faults in the system:

• In the event of temporary faults, e.g. overheating:

  All-wheel drive temporarily out of operation

• Permanent faults and serious faults:

  All-wheel drive out of order

The all-wheel drive control unit receives the following direct signals from the all-wheel drive actuator motor:

• All-wheel drive actuator motor rpm 1
• All-wheel drive actuator motor rpm 2
• Transmission oil temperature

The all-wheel drive control unit receives the following bus signal:

• Chassis FlexRay

The received signals are the basis for calculating the actuation of the all-wheel drive actuator motor.