Cummins ISB4.5 CM2150 Fault Code: 196 PID: 2558 SPN: 111 FMI: 4 Coolant Level Sensor 1 Circuit – Voltage Below Normal or Shorted to Low Source.

Circuit Description
The electronic control module (ECM) provides a 5 volt supply to the engine coolant level sensor using a common sensor supply circuit. The ECM also provides a ground on the sensor return circuit. The engine coolant level sensor provides a signal to the ECM on the engine coolant level sensor signal circuit. This sensor signal voltage changes based on the coolant level in the expansion tank.

Component Location
The engine coolant level sensor is typically located in the radiator top tank or surge tank. Refer to the OEM service manual for location.

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 ECM detects that the coolant level signal voltage is less than a calibratible value for more than 1 second.

Action Taken When the Fault Code is Active
-The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.
-No engine protection will be available for low coolant level.

Conditions for Clearing the Fault Code
-To validate the repair, start the engine and let it idle for 1 minute.
-The ECM will turn off the amber CHECK ENGINE light and the fault code will go inactive immediately after the diagnostic runs and passes.
-This fault code can also be cleared with INSITE™ electronic service tool.

Shop Talk
Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe® Online for applicable fixes to the calibration stored in the ECM. If necessary, recalibrate the ECM.

Possible Causes
-Open signal circuit in the engine harness, connectors, or sensor
-Signal circuit shorted to ground in the harness, sensor or connectors
-Damaged sensor.