The hydraulic unit of the brake system with its control unit for braking and driving dynamics has become part of standard equipment in many vehicle models.
The Electronic Stability Programme (ESP) has the task of preventing lateral swerving when cornering or when faced with critical situations, e.g. during extreme driving manoeuvres. The system specifically intervenes in the braking system and in the engine and transmission management and keeps the vehicle on track. It is important that during such intervention physical laws cannot be overridden. As soon as the limits are exceeded, even the ESP system cannot prevent the vehicle from swerving.
As the number of vehicles equipped with ABS/ASR or ESP increases, not surprisingly the frequency of faults and the need for repairs in the workshop also increase.
The first step is the reading out of the error memory. Any errors that occur are stored here and provide initial indications of the possible cause of the error. The stored error can give a direct indication about a defective component (Figure - Error memory 2) or about a short circuit/cable interruption. This allows targeted repair work to be carried out.
If no errors are stored in the error memory, parameters can be read out and evaluated specifically with the aid of an actual value query. Technical documents with the required set points are necessary for the evaluating of the displayed actual values, unless these are stored in the diagnostic unit. Errors which are stored in the error memory are also displayed during the actual value query.
Another test option is the actuator test. During this test, individual components can be controlled by the diagnostic unit and thus their functioning checked.
In this function, components, such as the sensors of the vehicle dynamics control system, can be set or adapted according to manufacturer values. The prerequisite for a basic setting is a vehicle system in perfect working order.
Special system and control unit information can be called up here.
System-specific circuit diagrams can be taken from vehicle information and used for troubleshooting purposes. This is where the PIN assignment on the control unit plug or the cable colours can be read and used for further testing on the electric vacuum pump or on the brake booster pressure sensor.
