Abs Does Not Operate Efficiently

CAUTION: If Anti-Lock Brake System/Traction Control Electronic Control Unit (ABS/TRAC ECU) replacement is necessary during testing, always ensure ABS/TRAC ECU connectors and ground circuit are okay. If either is suspect, repair and repeat testing to confirm ABS/TRAC ECU malfunction.

Retrieve Diagnostic Trouble Codes (DTC). See RETRIEVING DIAGNOSTIC TROUBLE CODES under DIAGNOSIS & TESTING. If any DTCs are present, perform appropriate diagnostic test. If no DTCs are present, check speed sensor circuit. Perform appropriate wheel speed sensor circuit test. See DIAGNOSTIC TROUBLE CODE IDENTIFICATION table under DIAGNOSIS & TESTING. Check brakelight switch circuit. See DTC C1249/49: BRAKELIGHT SWITCH CIRCUIT under DIAGNOSTIC TESTS. Check ABS/TRAC actuator. See ABS/TRAC ACTUATOR CHECK under COMPONENT TESTS. If ABS/TRAC actuator is not okay, check hydraulic system for leakage. See Figure. If all preceding tests are okay, replace ABS/TRAC ECU.