Anti-Lock Brake System - 4.3L: Diagnosis: Notes

NOTE: When testing and diagnosing 4WAL system, use of Tech 1 or other scan tester is required.

The Vehicle Control Module (VCM) contains a self-diagnostic capability to detect system failures. When a DTC is set, the VCM may disable 4WAL system and illuminate ANTI-LOCK light for duration of ignition cycle. DTCs stored by VCM can be displayed using Tech 1 and appropriate cartridge.

Before diagnosing 4WAL system, perform a comprehensive visual inspection of system by checking wiring harness connectors, harness routing (pay particular attention to wheel speed sensor wiring harness routing), applicable fuses in fuse block, and ground connections. Ensure brake fluid level in master cylinder reservoir is full.

Start 4WAL system diagnosis with appropriate FUNCTIONAL TEST under TROUBLE SHOOTING CHARTS. See Figure or Figure . If failures are found during FUNCTIONAL TEST, you will be directed to enter diagnostics to retrieve DTCs or perform symptom diagnosis. FUNCTIONAL TEST may indicate 4WAL system is functioning properly.