Initial Inspection and Diagnostic Overview

The electronic control unit monitors the Anti-Lock Brake System (ABS) constantly. The system must be checked when the ABS indicator lamp does not go out, comes on while driving or does not come on when ignition is turned on. A BMW service tester is required to check any malfunction of the system.
When testing the anti-lock brake system, ensure all other electrical components are turned off. Ensure ignition switch is turned off, then connect diagnostic equipment.