Diagnostic Aids
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2003 GMC Yukon XL, 2003 GMC Yukon, 2003 Chevrolet Tahoe, 2003 Chevrolet Suburban, and 2003 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
The malfunction must be present during diagnosis in order to prevent unnecessary parts replacement. Always begin diagnosis with DIAGNOSTIC SYSTEM CHECK - ABS (W/O JL4) or DIAGNOSTIC SYSTEM CHECK - ABS (W/JL4) .