A Symptoms - Antilock Brake System

Important: The following steps must be completed before using the symptom tables.

1. Perform the A Diagnostic System Check - ABS
^ There are no DTCs set.
^ The control module(s) can communicate via the serial data link.
2. Review the system operation in order to familiarize yourself with the system functions. Refer to the following:
^ ABS Description
^ ABS Operation

Visual/Physical Inspection
^ Inspect for aftermarket devices which could affect the operation of the antilock brake system.
^ Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
^ Inspect the master cylinder reservoir for the proper brake fluid level.

Intermittent
Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent and Poor Connections

Symptom List
Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:
^ No Communication with EBTCM
No Communication With EBTCM
^ ABS Indicator Inoperative
ABS Indicator Inoperative
^ ABS Indicator Always On
ABS Indicator Always On
^ Traction Control Indicator Always
Traction Control Indicator Always On
^ On Traction Control Indicator Inoperative
Symptom Related Diagnostic Procedures

Circuit Description
The Keyword 2000 serial data link allows information to be exchanged from module to module as needed. This is done by the ECM, the ECM requests and sends all the information that is transmitted on the Keyword 2000 line. When a scan tool is connected to the Keyword line it takes over for the ECM and sends and requests the needed information.

Diagnostic Aids
^ Thoroughly inspect the wiring and the connectors. Failure to carefully and fully inspect the wiring and the connectors can result in misdiagnosis. Misdiagnosis may cause replacement of parts without repairing the malfunction.
^ If an intermittent malfunction exists, refer to Intermittents and Poor Connections.

Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
2. This step checks if the scan tool can communicate with other modules on the Keyword 2000 serial data line. If the scan tool can communicate with other modules, then the malfunction is likely with the ignition input, ground or the serial data line to the EBTCM.