Anti-Lock Brake System: Diagnosis: Notes

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

The Brake Pressure Modulator Valve (BPMV) contains a self-diagnostic capability to detect system failures. When a fault code is set, the BPMV may disable 4WAL system and illuminate ANTI-LOCK light for duration of ignition cycle. Fault codes stored by BPMV can be displayed using Tech 1 scan tool with appropriate cartridge.

Before diagnosing 4WAL system, perform a comprehensive visual inspection of system by checking wiring harness connectors forlooseness and 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 DIAGNOSTIC SYSTEM CHECK. See DIAGNOSTIC CHARTS .