Cummins ISX12 CM2250 (2010-12) Fault Code: 3492 PID: SPN: 251 FMI: 10 Real-Time Clock- Abnormal Rate of Change

Circuit Description
The real-time clock consists of a timing chip internal to the electronic control module (ECM) which monitors engine off time, i.e. how long the engine has been shut down.

Component Location
The real time clock is a timing chip internal to the ECM and can not be serviced separately.

Conditions for Running the Diagnostics
This diagnostic runs after initial key ON and takes approximately 15 minutes to complete.

Conditions for Setting the Fault Codes
The engine off timer is not counting correctly and does not match other timers in the ECM.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE lamp and/or Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.
The ECM will not be able to monitor engine off time accurately.
Conditions for Clearing the Fault Code
To validate the repair, key OFF for 1 minute, then key ON for 15 minutes.
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 amber CHECK ENGINE lamp after the diagnostic runs and passes.
For On-Board Diagnostic (OBD) engines, the ECM will turn off the MIL after three consecutive trips where the diagnostic runs and passes.
The Reset All Faults command in INSITE? electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk
Monitoring the engine off time is necessary in to make sure that all other engine sensors and actuators are performing correctly. If the ECM is recalibrated or replaced during the repair and the fault code is no longer present, the instructions in the “Conditions for Clearing” section must be followed in order for the diagnostic to run again and validate the repair.

Potential causes of this fault code include:

Malfunctioning real time clock chip internal to the ECM
Engine calibration issue.

Possible Cause:
1) ECM calibration