Abs Does Not Operate Efficiently

CAUTION: If Anti-Lock Brake System (ABS) Electronic Control Unit (ECU) replacement is necessary during testing, always ensure ABS ECU connectors and ground circuit are okay. If either is suspect, repair and repeat testing to confirm ABS 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 circuits. See DIAGNOSTIC TROUBLE CODE IDENTIFICATION table under DIAGNOSIS & TESTING. Check brakelight switch circuits. See DTC 49: BRAKELIGHT SWITCH CIRCUIT under DIAGNOSTIC TESTS. Check ABS actuator. See ABS ACTUATOR CHECK under DIAGNOSIS & TESTING. If ABS actuator is not okay, check hydraulic system for leakage. If all preceding tests are okay and ABS still does not operate efficiently, replace ABS ECU.