Operation

Operation
The DTC and DSC functions can be activated and deactivated by means of the DSC button in the centre console switch centre (SZM). Briefly pressing the button activates the DTC function. Press the button for a longer period (approximately 3 s) deactivates the DSC function. The ABS function remains active however. The activated DTC function and the deactivated DSC function are indicated by means of warning and telltale lamps in the instrument cluster.
If the DSC button is pressed for longer than 10 s, the DSC function is activated and cannot be deactivated until the next ignition ON. This is a safety function for such a scenario where an object placed on the centre console (e.g. a handbag) presses down on the DSC button.

Notes for Service
Service Information
An open circuit to the rotation rate sensor is not detected.
After the battery has been disconnected, the steering angle sensor must relearn its offset. The steering angle is only learned by the DSC control unit when the vehicle is driven off. If the DSC control unit does not receive the steering angle offset before the vehicle reaches 25 km/h, the DSC telltale in the instrument cluster lights up.
A different DSC control unit is used in vehicles equipped with active steering. The control units for vehicles with active steering and without active steering differ in the matching resistors they use.

Diagnosis
Diagnosis is performed by means of the PTCAN.

Programming
Flash programming of the control unit is possible by means of the PTCAN.

Coding
The DSC control unit detects automatically whether the relevant vehicle is fitted with ACC, Dynamic Drive or Active Front Steering.
The SPA function must be coded.

Tire Defect Indicator (RPA)
The RPA function is integrated in the DSC control unit. The system compares by way of the wheel speeds the tire tread circumferences of the 4 wheels.
The RPA system does not monitor the uniform diffusion loss over all 4 tires. If the same pressure loss occurs in the 4 tires, the wheel speeds change to the same extent and the pressure loss is not detected. The customers must regularly monitor inflation pressures themselves.
The system must be reinitialized when tire inflation pressures are changed or when the tires are changed. The RPA is initialized by means of the controller at terminal 15 ON. The system switches to the "Learning phase" status. This status is shown in a status line in the
Central Information Display (CID). After a brief driving time, the system learns the new wheel speeds as reference values.
For the RPA there are 2 variable warning lamps with 2 associated Check Control messages (CC messages) which are displayed in the instrument cluster:
^ Tire puncture signals a loss of pressure of more than 30% in a tire. This is accompanied by a gong sound.
^ Run Flat Indicator failure signals that the system is inactive due to a fault and can not detect any tire failures.





Explanatory notes pertaining to the relevant CC messages appear in the CID.
The RPA submenu in the CID also features a status line which indicates the current RPA status.
^ Learning phase, i.e. the system is standardized. The learning phase is indicated until RPA is ready for operation the first time after the start of standardization.
^ Inactive because there is a fault in the system and thus no tire failure can be detected.
^ Active when the system can detect a tire failure.

Parking Brake





The parking brake is actuated by means of a conventional hand-brake lever. The hand-brake lever is located on the centre console and bolted to the floor pan.
The parking brake is equipped with an automatic cable adjuster (ASZE) and a compensating element.
The mounting clip locks the cables in the compensating element. The duo servo brakes correspond to the duo servo brakes of the E65 (dia. 185 x 30 mm).





The function of the ASZE is to adjust the hand brake cables and compensate longitudinal variations and settling. It does not however adjust the wear on the duo servo brake. This must, as before, be adjusted at the expander lock in the brake. The function of the compensating element is to distribute the actuating force uniformly to both hand brake cables.





Notes for Service:
If there is a cable break, the automatic cable adjuster is in the most untensioned position.

Removing the cables:
^ To replace the cables, it is necessary to remove the centre console and the rear compartment ventilation ducts.
^ For the cables to be removed, the parking brake lever must be in the released position.
^ For the cables or the duo servo brakes to be changed, the ASZE unit must be deactivated.





Deactivating the ASZE unit:
A screwdriver must be used to press back the locking clip of the tensioning spring until the locking hook engages the locking clip of the tensioning spring.





The cables can now be disconnected from the duo-servo brakes. To be able to disconnect the cables, it is necessary to remove the mounting clip.

Installing the cables:
^ For the cables to be installed, the parking brake lever must be in the released position. The cables do not automatically feed themselves into the compensating element on insertion but rather must be guided with a screwdriver into the correct position.
^ To secure the cables in the compensating element, it is necessary to attach the mounting clip.
^ The cables are connected to the duo-servo brakes.
^ The ASZE can be reactivated by levering the locking hook out of the locking clip.

Adjusting the duo servo brakes:
The basic clearance of the duo servo brake is adjusted at the adjusting screw of the duo servo brake shoes. The parking brake is automatically adjusted when the ASZE unit is activated.