Cummins ISX12 CM2250 (2010-12) Fault Code: 3366 PID: SPN: 111 FMI: 18 Coolant Level- Data Valid But Below Normal Operating Range- Moderately Severe Level

Circuit Description
The coolant level sensor is a switch and is used to measure the level of the engine coolant in the radiator top tank. The coolant level sensor is immersed in the coolant and returns a different signal voltage when immersed in coolant versus being out of coolant. The engine control module (ECM) monitors the change in the signal voltage to determine the level of the engine coolant.

Component Location
The engine coolant level sensor is typically located in the radiator top tank or surge tank. Refer to the original equipment manufacturer (OEM) service manual.

Conditions for Running the Diagnostics
This diagnostic runs continuously when the keyswitch is in the ON position or when the engine is running.

Conditions for Setting the Fault Codes
The engine control module (ECM) detected the coolant level sensor signal voltage was greater than 3-VDC for more than 30 seconds and engine coolant temperature was greater than 107?C [225?F].

Action Taken When the Fault Code is Active
The ECM logs the fault code immediately when the diagnostic runs and fails.
For On-Board Diagnostic (OBD) engines, the ECM illuminates the the Malfunction Indicator Lamp (MIL) immediately after three consecutive trips in which the diagnostic runs and fails.
Conditions for Clearing the Fault Code
To 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.
For 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
This fault code goes active when the coolant level has fallen below the minimum required level. Fill the top tank with coolant.

Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

For intermittent power supply and data link communication issues with Aftertreatment Components, it is highly recommended that the OEM Power Distribution Center fuses and relays be thoroughly checked for loose, missing, or intermittent connections.

Possible Cause:
1) ECM calibration