Diagnostic System Check - ABS

ABS Schematic:

SYSTEM DESCRIPTION
The diagnostic system check is an organized approach to identifying a ABS malfunction. It must be the starting point for any ABS complaint diagnosis because it directs the service technician to the next logical step in diagnosing the complaint. Scan Tool serial data (ABS only) is transmitted/received by the 10-way Electronic Brake Control Module (EBCM) connector, terminal F (CKT 799). Ignition voltage is supplied through the 10-way EBCM connector, terminal A (CKT 441). Signal ground is supplied through the 10-way connector, terminal J (CKT 451).

DIAGNOSTIC AIDS
Using the Scan Tool, communication with the EBCM can be attempted by reading a Diagnostic Trouble Code (DTC) or by reading the data list. Excessive resistance in the ground or power supply circuits will not allow communication with the EBCM. If communication with the EBCM is not possible, ensure the ABS ground connection is good and that there is no excessive resistance in any of the power supply circuits.

Diagnostic System Check (Part 1 Of 2):

Diagnostic System Check (Part 2 Of 2):

TEST DESCRIPTION
Numbers below refer to numbers on the diagnostic chart.
(3) Checks proper ANTILOCK indicator lamp operation.
(4) Checks for correct ignition voltage at the EBCM.
(5) Checks for high resistance in the EBCM ground circuit.
(9) Checks for high resistance in the EBCM ignition voltage circuit.
(10) Checks for short to ground in the ignition voltage circuit.