Transfer Case: Service Precautions

Notes on Towing, Test and Repair Work

Towing
There are no further restrictions when towing on both axles with regard to 4MATIC vehicles. The vehicle can be towed with a raised front or rear axle with the ignition switched off over a distance of a maximumof 50 km at a maximum speed of 50 km/h. Over longer distances, when the front axle is raised the propeller shaft to the rear axle must be disconnected at the flange, and when the rear axle is raised the propeller shaft to the front axle must be disconnected at the flange (lubrication deficiencies in the transfer case).

Brake test bench - vehicle performance tester - speedometer tester
Move the service valve or coding plug into the test position. When driving on test benches with stationary front wheels, the transfer case does not have a sufficient supply of lubricating oil therefore driving must be restricted to a maximum of 15 minutes. If a test lasts longer, the vehicle must be driven on the road for approximately 1 km.

Hydraulic system
The system must be switched to a depressurized condition before all work on the hydraulic system by switching the service valve or the coding plug to the test position and relieving the accumulator pressure at the pressure relief plug on the 4MATIC control unit.

Welding work
When welding with an electrical welder the following points are to be noted:
- Disconnect negative terminal of the battery.
- Connect ground terminal of the welder directly to the part to be welded.

Level control
If the lever on the service valve is in the test position, the pressure side of the level control is depressurized. If the coding plug is in the test position, the accumulator pressure must also be relieved at the pressure drain plug on the 4MATIC valve control unit. In the event of faults, apart from the normal remedial action, also test the hydraulic system (refer to "test program - hydraulics").

Front wheel bearings
To avoid damage to the front wheel bearings, the vehicle must not be placed on its front wheels when the front axle shafts are removed and it must not be moved.

ABS testing
The left front axle speed sensor (L6/1) can no longer be tested with the Bosch tester or the DB test adaptor Part No.126 589 09 21 00. Testing is carried out with the electricall electronic test program or by self-diagnosis (pulse readout).

If the cable between the ABS control unit (N30) connection 13 and the 4MATIC control unit (N30/3) connection 23 is interrupted or the 4MATIC control unit (N30/3) is unplugged, the ABS warning lamp (A1e17) comes on after approximately 20 seconds. This additional potential fault must be taken into account.