Function

ABS/EDL/ASR/ESP Bosch 5.3, On Board Diagnostic (OBD)
The Electronic Stabilization Program (ESP) is a driving dynamics regulation system. It stabilizes the vehicle both in understeer and oversteer situations. ESP works throughout the entire speed range. When ESP is in regulation mode, the ESP indicator lamp blinks three times per second.

A few seconds after engine is started and driving begins, a light pumping noise may be audible. This is not a malfunction. It is the self-monitoring function of the ESP system.

ESP is another addition to the existing driving safety systems.
ESP increases vehicle safety during critical driving situations. It reduces the likelihood of skidding relative to the well-known safety systems and improves steering control.

Function
Because the control modules are interconnected via a data-BUS wire, the DTC memory contents of all control modules installed in the vehicle must always be checked at the beginning of troubleshooting procedures.

This is done via the "Automatic Test Sequence" which is activated via button function 00.
Be sure to check whether a stored malfunction might be influencing the ABS system.

The On Board Diagnostic (OBD) function relates to the electrical and electronic parts of the ABS system; i.e. it can only recognize malfunctions (e.g. interruption of a wheel speed sensor) via the electrical connection to the control module.

The 88-pin ABS Control Module (w/EDL) -J104is located at right behind the instrument panel at the heating / A/C housing. The hydraulic unit with booster pump is located at left in the engine compartment. The control module is equipped with DTC memory. The connection for On Board Diagnostic (OBD) is located under the cover for the steering column.

The control module recognizes malfunctions during vehicle operation and saves DTCs in permanent memory; this information is retained even when battery voltage fails.

Sporadically occurring (periodic) malfunctions are also recognized and stored as DTCs. If this malfunction does not occur again within 50 vehicle starts and driving procedures, it will be erased from DTC memory, except for the malfunction "control module faulty". (malfunction removal counter)

After ignition is switched on and/or engine is started, the ABS Warning Light -K47-, the red warning light for brake system -K118-, and the ESP Control Lamp -K155- light up for approximately 2 seconds.

A test sequence (self-test) is performed in the control module during this time, with the functions:
^ Supply voltage is tested to determine whether it is at least 10.0 volts.
^ The control module and valve coils are checked.
^ The control module coding is checked.
^ A static wheel speed sensor test is performed (without speed signal).
^ An electric test of the wheel speed sensors is performed; this test will not complete successfully unless vehicle is driven for 30 seconds at above 60 km/h.

VAG1551 Scan Tool (ST) or VAS5051 tester
Always initiate On Board Diagnostic (OBD) to start troubleshooting. Electrical malfunctions that affect braking are stored in DTC memory. They can be recognized using the VAG1551 Scan Tool (ST) or the VAS5051 tester.
The indicated diagnostic data leads to a DTC table with notes regarding potential malfunction causes and specific repair procedures.