General
General
The 4MATIC is a four-wheel drive system in which the drive of the front wheels can be engaged automatically if required along with the permanent rear-wheel drive. In addition, if required, the center differential lock in the transfer case and the ASD rear axle differential lock are engaged automatically.
The engagement of the 4MATIC is controlled electronicallylhydraulically in 3 stages without involving the driver.
Shift stage 0 - rear-wheel drive
Shift stage 1 - four-wheel drive compensated
Shift stage 2 - four-wheel drive locked inter-axle
Shift stage 3 - four-wheel drive locked inter-axle and inter-wheel
Automatic engagement of the 4MATIC offers not only optimized traction, but a high degree of driving safety compared to other systems. 4MATIC vehicles are fitted with ABS as standard.
When braking, all differential locks and the four- wheel drive are disengaged. The driving stability and the effect of ABS are therefore retained during braking.
Driving with 4MATIC
Warning lamp and function indicator lamp Two displays with various symbols are located in the instrument cluster for the 4MATIC. In key position two in the steering lock, the ASDI 4MATIC (A1e25) function display and the yellow ASD/4MATIC (A1e24) warning lamp in the instrument cluster come on and go out when the engine is running.
When driving, the ASD/4MATIC (A1e25) function indicator lamp shows that the 4MATIC is engaged. It warns the driver that he is driving near the limit and that the tires are approaching the limit of adhesion. He can then better adapt his driving style to suit the changed road conditions.
Shift stage 1 is always engaged when starting off. The function indicator lamp however does not come on provided there is no wheel skid.
The ASD/4MATIC (A1e25) function indicator lamp is controlled via a 4-pin plug connection on the back of the instrument cluster. The brightness of the function indicator lamp is reduced when the lights are switched on to prevent any distraction when driving at night.
The ASD/4MATIC (A1e24) warning lamp is controlled via a 2-pin plug connection on the back of the instrument cluster. If it comes on when the engine is running, the 4MATIC is inoperative. There is an electrical or hydraulic fault.
In this case, switch the service valve or relocate the coding plug into test position and have fault eliminated as soon as possible. In the test position, the 4MATIC and the level control are inoperative.
An electrical fault in the 4MATIC (N30/3) control unit is stored for subsequent interrogation. It can be called up at the test coupling (X11/4) located in the components compartment.
Location of components
Electrics/electronics
A1e17 ABS warning lamp
A1e24 ASD/4MATIC indicator lamp
A1e25 ASD/4MATIC function indicator lamp
K1/2 Overvoltage protection relay 87E/87L/30a (9-pin) (series K1/1)
L6 Rear axle speed sensor
L6/1 Left front axle speed sensor
L6/2 Right front axle speed sensor
N30 ABS control unit
N30/3 4MATIC control unit
N49 Steering angle sensor
S9/1 Stop lamp switch (4MATICIASD)
X11/4 Test coupling for diagnosis, pulse readout (8-pin)
Hydraulics
2 Oil reservoir
6 Level control height controller
12 Pressure oil pump
15 Service valve
A7 ABS hydraulic unit
A7/2 4MATIC valve control unit
Mechanical
1 Transfer case
4 Front-wheel drive propeller shaft
8 Front axle differential with front axle shafts
9 ASD locking rear axle differential