The real-time clock battery is connected to the engine harness main branch directly under the 50-pin engine ECM connector.
The ECM uses the real-time clock feature to time-stamp faults and other data with the time and date. The battery is used to power the real-time clock circuitry in the ECM when vehicle battery power is removed from the ECM. If a battery is installed, the ECM clock will maintain the correct time and date with power removed from the ECM, provided the engine harness connector remains plugged into the ECM.
If a real-time clock battery is not installed on the engine, it will be necessary to set the time and date using INSITE™ electronic service tool whenever the real-time clock feature is enabled in the ECM and vehicle battery power is removed from the ECM.
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