Pre-Diagnostic Inspection

When checking potential ABS/TCS faults, check following before performing diagnostic trouble code testing:

1. Check all fuses related to ABS/TCS operation.
2. Check all ABS/TCS wiring harness connectors for proper engagement, loose wires or terminals and/or corrosion. Check harness routing; pay particular attention to wheel speed sensor wiring harness routing.
3. Ensure parking brake switch is functioning properly.
4. Ensure brake switch is properly adjusted.
5. Check brake system for leaks and proper fluid level.
6. Check ABS/TCS ground circuit for clean tight connections. See appropriate diagram in GROUND DISTRIBUTION article in WIRING DIAGRAMS.
7. Always perform diagnostic system check before diagnosing DTCs. See DIAGNOSTIC SYSTEM CHECK .