Test Description

When a malfunction occurs in the ABS system, the EBCM will activate the amber Anti-Lock Warning Lamp. Before performing diagnosis on the ABS system when the warning lamp comes on, check that the EBCM connector and all other system electrical connectors are secure and that fuses are satisfactory. Refer to DIAGNOSTIC CHARTS, for ABS system functional check. Sometimes use of the compact spare will activate a wheel sensor fault code and deactivate the ABS system, if this occurs, recycle the ignition switch to reset the system.
There are either thirteen or fifteen trouble codes that may be set by the EBCM, Refer to DIAGNOSTIC CHARTS/ABS TROUBLE CODE & SYMPTOM CHART. All codes except 72 will cause the EBCM to disable the ABS system, allowing power assisted braking only.
The EBCM performs an automatic (AUTO) test once each ignition cycle when vehicle reaches approximately 4 mph. The AUTO test cycles each solenoid valve and pump motor to check component operation. If any error is detected during this test the EBCM will set a trouble code. This test may be heard and felt while it is taking place and should be considered normal mode of operation.
The EBCM can display codes only when the "Diagnostic Service Mode" has been entered. There are two ways to enter the diagnostic service mode, either using a TECH 1 diagnostic computer, or by grounding pin "H" of the ALDL connector and using "Flash Code Diagnosis". The use of a TECH 1 computer is recommended for diagnosing the ABS system.