With Scan Tool

This system contains sophisticated on-board diagnostics that can be accessed with a bi-directional scan tool.

NOTE: To properly diagnose the anti-lock brake system, a GM TECH 1 bi-directional scan tool or suitable equivalent is necessary. The scan tool can be used to identify system faults as specifically as possible, including whether or not the fault is intermittent. The scan tool can also be used to monitor the input and output signals of the ABS Module, manually control system components and perform automated functional tests. Using the scan tool allows for accurate fault confirmation and repair verification.

1. Connect GM TECH 1 or suitable equivalent to Data Link Connector (DLC), then read all current and history diagnostic trouble codes.

NOTE: Be sure to note which diagnostic trouble codes are current failures. Do not clear diagnostic trouble codes unless directed to do so.

2. Read "CODE HISTORY" data, note diagnostic trouble codes stored and their frequency of failure. Ensure to note the last diagnostic trouble code entered and the conditions present when the failure occurred. This last diagnostic trouble code should be the starting point for diagnosis and repair.