Circuit DescriptionUnder ordinary operating conditions, the real-time clock in the Electronic Control Module (ECM) is powered by the vehicle’s batteries. If battery power to the ECM is lost, then the real-time clock will be powered by a battery in the engine harness (if equipped).

Component LocationThe real-time clock battery is secured to the engine harness near the ECM.

Conditions for Running the DiagnosticsThis diagnostic runs continuously when the keyswitch is in the ON position.

Conditions for Setting the Fault CodesThe ECM detects that the real-time clock battery voltage is 3.3-VDC.

Action Taken When the Fault Code is ActiveThe ECM flashes the amber CHECK ENGINE light and/or illuminates the Malfunction Indicator Lamp (MIL) at initial key-on when the diagnostic runs and fails.The real-time clock values in the ECM data will be incorrect.Conditions for Clearing the Fault CodeTo validate the repair, start the engine and let it idle for 1 minute.The fault code status displayed by INSITE? electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.The ECM will turn off the flashing amber CHECK ENGINE lamp after the diagnostic runs and passes.The ?Reset All Faults? command in INSITE? electronic service tool can be used to clear active and inactive faults.

Shop TalkThis fault indicates that the real-time clock in the ECM lost power. Possible causes for this fault are weak or damaged real-time clock battery, damaged wiring or connectors between the battery and ECM, or the engine is not equipped with a real-time clock battery and the vehicle battery power to the ECM is lost.

Possible Cause:1) Real-Time Clock Battery failure2) Engine Harness3) ECM calibration