Cummins ISB6.7 CM2350 (2013-17) Fault Code: 4866-2 Wire PID: SPN: 6303 FMI: 4 Engine Coolant Level 2 Sensor Circuit – Voltage Below Normal, or Shorted to Low Source. Low signal voltage detected at the engine coolant level 2 circuit.
Cummins ISB6.7 CM2350 (2013-17) Fault Code: 4866-2 Wire PID: SPN: 6303 FMI: 4 Engine Coolant Level 2 Sensor Circuit – Voltage Below Normal, or Shorted to Low Source. Low signal voltage detected at the engine coolant level 2 circuit.
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 OEM service manual for the 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 Engine Control Module (ECM) detected the coolant level 2 signal voltage was 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 lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.
Conditions for Clearing the Fault Code
1)To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
2)The fault code status displayed by INSITE? electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3)The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
4)For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.
5)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.
Possible Causes:
1)A malfunctioning engine coolant level sensor
2)An open circuit in the OEM harness
3)A short circuit to ground in the OEM harness
