Control Unit
The ESP control unit is integrated into the ABS/TC control unit. It compares the driver requirement (nominal characteristic), with the vehicle characteristics (actual characteristic) and, if necessary, actuates the relevant regulators in order to maintain the vehicle in a stable, driveable state (maximum possible adhesion between tyres and road surface). Disturbance variables such as road surface conditions, brake status, driving manoeuvres of the driver, slip and wheel status are taken into account.
Hydraulic Modulator
The ABS 5.3/TC/ESP hydraulic modulator features an additional connection (1) for the pressure sensor.
Note. During all operations on the hydraulic modulator or on the ABS 5.3/TC/ESP control unit, it is essential that the cleanliness of the components is ensured.
Yaw Rate / Acceleration Sensor
The yaw rate / acceleration sensor (1) detects all vehicle movements in the longitudinal and lateral directions. In addition, the rotating movements of the vehicle about the vertical axis are determined via detection of the centrifugal forces generated.
The yaw rate/acceleration sensor is attached to a certain position on a bracket between the left front sill panel and left front seat in the B-pillar area.
The yaw rate/acceleration sensor is very susceptible to damage through extreme vibration, e.g. hard blows. For this reason, a yaw rate/acceleration sensor that has been dropped on the ground must be replaced in most cases.
Note. When repairing vehicles which are accident-damaged in the area of the yaw rate / acceleration sensor, the exact position of the retaining plate and also the angle of inclination of the retaining plate must be observed. Non-observance can result in the malfunctioning or failure of the system.
Steering Angle Sensor
The steering angle sensor (2) is mounted directly on the steering shaft at the lower end of the steering column assembly. It is connected to the steering shaft via an adapter sleeve. The outer part of the housing is secured against rotation by a journal (1) engaging in the steering column bracket guide.
Note. In order to prevent malfunctions, the steering angle sensor must be re-calibrated / adjusted to "0" using TECH 2 after operations on the steering column and after replacement.
Before beginning the calibration, ensure that the steering wheel is in the straight-ahead position and is not turned during calibration.
Pressure Sensor
The pressure sensor (1) is attached to the ABS 5.3/TC/ESP hydraulic modulator. It converts the pressure condition in brake circuit 2 (see diagram of hydraulic system) of the brake master cylinder into digital signals and transmits them to the ESP control unit. The driver's braking requirement and brake application force is thus detected.
Note. The pressure sensor cannot be repaired and must be completely replaced if defective. Used pressure sensors must not be stored as they contain brake fluid, which is hygroscopic – corrosion hazard. The seal to the ABS hydraulic modulator is via a conical surface. Additional sealing washers or sealant must not be used.
Remove Brake Lines from Brake Master Cylinder to Hydraulic Modulator
The brake lines from the brake master cylinder to the hydraulic modulator are of the "Tite flex" type for vehicles with ESP (flexible adapter) and are of a larger diameter compared to brake lines on vehicles without ESP.
Note. When removing and installing the brake lines from the brake master cylinder to the hydraulic modulator, special care must be taken to ensure contact-free routing.
Brake lines of the "Tite flex" type must always be replaced as a complete unit.
Telltale Lamp
The ESP telltale is located in the instrument panel. It indicates intervention or failure of ESP or TC to the driver. This telltale applies to both systems.
As a bulb check to see, it illuminates briefly when the ignition is switched on if ESP and TC systems are functioning correctly. When driving, the telltale only illuminates during corrective intervention of ESP or TC. If the telltale illuminates continuously, the fault memory must be read out using TECH 2 and any faults must be remedied.
Switch-Tc/esp
As ESP is combined with TC, pressing the TC/ESP switch turns both systems off.
The TC/ESP is located in the same place as the TC switch on vehicles without ESP. Visually, it may be distinguished via another symbol on the switch.
