(Basic Function Of All-Wheel Drive Control Unit - GF28.19-P-9891A)
Model all with transmission 700.4, 724.0/1
with code M005 (Vehicles with 4MATIC/all-wheel drive)
Example illustration
Overview
This document contains the following information: '
- General
- Function
Location
The all-wheel drive control unit actuates the all-wheel drive actuator motor in the locking differential drive unit according to the driving situation.
Function
When the multiplate clutch in the rear axle differential is activated by the all-wheel drive actuator motor, the drive torque is distributed from the front axle to the rear axle. Depending on the transfer case, up to 100 % of the drive torque can be passed on to 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.