Pre-Diagnostic Inspection

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

• Check ABS fuse No. 19 (10-amp) and HAZARD fuse No. 12 (20-amp) in instrument panel fuse block located behind left side of instrument panel.
• Check fuse V1 (80-amp) in power distribution fuse block located in left front of engine compartment.
• Check all ABS/TCS wiring harness connectors for proper engagement, loose wires or terminals and/or corrosion. Check harness routing paying particular attention to wheel speed sensor wiring harness routing.
• Ensure brake switches are properly adjusted.
• Check brake system for leaks and proper fluid level.
• Check ABS/TCS ground circuit for clean tight connections. Ground is located in left front of engine compartment, in body and instrument panel wiring harness.
• Always perform diagnostic system check before diagnosing DTCs. See DIAGNOSTIC SYSTEM CHECK  .

Solenoid valve relay is turned off by EBCM when a diagnostic trouble code is set. Using scan tool to monitor data list when trouble codes are set, solenoid will be displayed as being off. This is normal and not an indication of a system malfunction.

EBCM performs an automatic test during each ignition cycle when vehicle speed reaches 4 MPH in either forward or reverse gears. Automatic test cycles each solenoid valve, pump motor and relays to check component operation. EBCM will set a trouble code if an error is detected. Test may be felt and heard while it is taking place and is a normal mode of operation.