Function

Anti-Lock Brake System with Electronic Differential Lock Bosch 5.3 With ABS/EDL

Function
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 31-pin ABS control module (w/EDL) -J104- forms a compact hydraulic control module with the hydraulic unit. The hydraulic control module is located on the left-hand side of the engine compartment. The control module is equipped with DTC memory. The connection for On Board Diagnostic (OBD) is located under the cover to the right of the instrument cluster.

The control module recognizes malfunctions during vehicle operation and stores them in a DTC memory. This information is retained even if battery voltage fails.

Periodically occurring malfunctions are also recognized and stored as DTCs. If this malfunction does not occur again for 20 vehicle starts or one long trip, the DTC is erased from DTC memory.

After ignition is switched on and/or the engine is started, the ABS Warning Light -K47- and the red brake and parking brake warning light -K7- 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 (minimum 10.0 volts).
^ Control module and valve coils are checked
^ 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.