Engine Coolant Temperature – Data Valid But Below Normal Operating Range – Moderately Severe Level
Overview
| CODE | REASON | EFFECT |
| Fault Code: 2789 PID: P110 SPN: 110 FMI: 1/18 LAMP: Amber SRT: |
Engine coolant temperature is below normal operating temperature limits.
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None on performance.
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Engine Coolant Temperature Sensor Circuit
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Circuit Description
The coolant temperature sensor is a variable resistor sensor and is used to measure the temperature of the coolant of the engine. The engine control module (ECM) supplies 5 volts to the coolant temperature signal circuit. The ECM monitors the change in voltage caused by changes in the resistance of the sensor to determine the coolant temperature.
Component Location
The engine coolant temperature sensor is located on the thermostat housing.
Conditions for Running the Diagnostics
This diagnostic runs continuously when the engine is running.
Conditions for Setting the Fault Codes
Engine coolant temperature was less than 60C [140F] for over 1 hour during a period of extended idle.
Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE lamp immediately when the diagnostic runs and fails.
Conditions for Clearing the Fault Code
- To validate the repair using a Diagnostic Road Test, utilize a route that incorporates both stop and go city type driving and steady state highway type driving. It may be necessary to load the unit for certain diagnostics in the ECM to run.
- To validate the repair using a Chassis Dynamometer, utilize a routine that incorporates acceleration and motoring events, steady state highway type operation, and load. This will simulate normal driving and allow the diagnostics in the ECM to run.
- The fault code status displayed by the recommended Cummins electronic service tool or equivalent will change to INACTIVE immediately after the diagnostic runs and passes.
- The “Reset All Faults” command in the recommended Cummins electronic service tool or equivalent can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.
If this fault indicates that coolant temperature is below a calibratible limit set in the ECM.
Refer to Engine Coolant Temperature Below Normal troubleshooting symptom tree tree in the base engine service manual.
Troubleshooting Summary
- Check for primary fault codes
- Coolant temperature sensor resistance check
- Malfunctioning cooling fan drive or cooling fan controls
- Thermostat is malfunctioning
- Out-of-chassis opening temperature test
- Radiator shutters malfunctioning (if equipped)
- Excessive coolant flow through OEM plumbing and heater cores
- ECM calibration revision history check
Verification
Conditions
- Turn keyswitch ON.
- Connect the recommended Cummins electronic service tool or equivalent.
Action
- Use the recommended Cummins electronic service tool or equivalent to read the fault codes.
Specification
Before troubleshooting this fault code, troubleshoot any fault code that is active or has more than one inactive count within the last 25 engine operating hours from the following list:
- Engine coolant temperature: 146, 151, 334, 2646, 2963
Linked Solutions
- None
Repair
- Perform a search on the appropriate fault codes.
Validation
- None
Verification
Conditions
- Turn keyswitch OFF.
- Disconnect the coolant temperature sensor from the engine wiring harness.
Action
- Inspect the pins and connectors for damage.
- Measure the resistance between the engine coolant temperature sensor SIGNAL pin and engine coolant temperature sensor RETURN pin at the engine coolant temperature sensor.
Specification
- A malfunctioning temperature sensor has been detected if the resistance is not within the following specification: 180 – 160k Ω
Linked Solutions
- None
Repair
- Replace the coolant temperature sensor.
Validation
- Connect all components
- Connect the recommended Cummins electronic service tool or equivalent.
- Disable the fault code.
- Operate the engine within the “Conditions for Clearing the Fault Code” found in the Overview section of the troubleshooting procedure.
- Verify that the fault code is no longer active.
- Check ECM Calibration Revision History
- Use the recommended Cummins electronic service tool or equivalent to find the current ECM code and revision number in the ECM.
- Compare the ECM code and revision number in the ECM to the calibration revisions listed in the ECM Calibration Revision History Database for applicable changes related to this fault code.
- Refer to ECM Calibration Revision History Database.
Verification
Conditions
- Turn keyswitch ON.
- Connect the recommended Cummins electronic service tool or equivalent.
Action
- Use the recommended Cummins electronic service tool or equivalent.
- Check the adjustable parameters settings.
Ensure the following adjustable parameters are set correctly for the application:
- Fan Control Logic.
- Fan Control Switch.
- Air Conditioner Pressure Switch Input.
- Perform the Fan Override Test.
- Verify that the fan operates correctly.
- Verify the fan is engaging at the correct engine temperature.
Specification
- If the cooling fan operation is not within specification, then proceed to the Repair section.
Linked Solutions
- None
Repair
Repair or replace only the components that were found to be out of specification.
- Adjust, repair, or replace the component preventing correct cooling fan operation.
Validation
- Connect all components
- Connect the recommended Cummins electronic service tool or equivalent.
- Disable the fault code.
- Operate the engine within the “Conditions for Clearing the Fault Code” found in the Overview section of the troubleshooting procedure.
- Verify that the fault code is no longer active.
- Check ECM Calibration Revision History
- Use the recommended Cummins electronic service tool or equivalent to find the current ECM code and revision number in the ECM.
- Compare the ECM code and revision number in the ECM to the calibration revisions listed in the ECM Calibration Revision History Database for applicable changes related to this fault code.
- Refer to ECM Calibration Revision History Database.
Verification
Conditions
- Engine running.
Action
- Allow the engine to reach operating temperature.
- Check the thermostat opening temperature with an infrared temperature gun.
- Check the coolant thermostat for proper operation.
- Check for a damaged or leaking thermostat seal.
- If a temperature gun is not available or if the temperature gun reading is above the correct thermostat opening temperature, then proceed to Linked Solutions section.
Specification
- If any damage is noted or if the thermostat does not open at the correct temperature, then a malfunctioning coolant thermostat has been detected.
- If any damage or if the thermostat seal is found leaking, then a malfunctioning thermostat seal has been detected.
Linked Solutions
- Out-of-chassis opening temperature test
Repair
- Replace the engine coolant thermostat.
A new thermostat seal should be used when replacing the engine coolant thermostat.
If the thermostat seal is damaged, the engine coolant thermostat will still need to be replaced since the thermostat seal is not a separately serviceable item.
Validation
- Connect all components
- Connect the recommended Cummins electronic service tool or equivalent.
- Disable the fault code.
- Operate the engine within the “Conditions for Clearing the Fault Code” found in the Overview section of the troubleshooting procedure.
- Verify that the fault code is no longer active.
- Check ECM Calibration Revision History
- Use the recommended Cummins electronic service tool or equivalent to find the current ECM code and revision number in the ECM.
- Compare the ECM code and revision number in the ECM to the calibration revisions listed in the ECM Calibration Revision History Database for applicable changes related to this fault code.
- Refer to ECM Calibration Revision History Database.
Verification
Conditions
- Turn keyswitch OFF.
Action
- Perform the out-of-chassis opening temperature test.
Specification
- If any damage is noted or if the thermostat does not open at the correct temperature, then a malfunctioning coolant thermostat has been detected.
- If any damage or if the thermostat seal is found leaking, then a malfunctioning thermostat seal has been detected.
Linked Solutions
- None
Repair
- Replace the engine coolant thermostat.
A new thermostat seal should be used when replacing the engine coolant thermostat.
If the thermostat seal is damaged, the engine coolant thermostat will still need to be replaced since the thermostat seal is not a separately serviceable item.
Validation
- Connect all components
- Connect the recommended Cummins electronic service tool or equivalent.
- Disable the fault code.
- Operate the engine within the “Conditions for Clearing the Fault Code” found in the Overview section of the troubleshooting procedure.
- Verify that the fault code is no longer active.
- Check ECM Calibration Revision History
- Use the recommended Cummins electronic service tool or equivalent to find the current ECM code and revision number in the ECM.
- Compare the ECM code and revision number in the ECM to the calibration revisions listed in the ECM Calibration Revision History Database for applicable changes related to this fault code.
- Refer to ECM Calibration Revision History Database.
Verification
Conditions
- Turn keyswitch OFF.
Action
- Check for closed cold weather radiator cover or winterfront.
Specification
- If the radiator shutters do not operate according to the specification, then a malfunctioning radiator shutter assembly has been detected.
Linked Solutions
- None
Repair
- Repair or replace cold weather radiator cover or winterfront.
Refer to OEM Service Manual
Validation
- Connect all components
- Connect the recommended Cummins electronic service tool or equivalent.
- Disable the fault code.
- Operate the engine within the “Conditions for Clearing the Fault Code” found in the Overview section of the troubleshooting procedure.
- Verify that the fault code is no longer active.
- Check ECM Calibration Revision History
- Use the recommended Cummins electronic service tool or equivalent to find the current ECM code and revision number in the ECM.
- Compare the ECM code and revision number in the ECM to the calibration revisions listed in the ECM Calibration Revision History Database for applicable changes related to this fault code.
- Refer to ECM Calibration Revision History Database.
Verification
Conditions
- Turn keyswitch OFF.
Action
- Inspect the OEM installed cooling system components.
Specification
- If OEM installed cooling system components do not meet specification, then proceed to the Repair section.
Linked Solutions
- None
Repair
Repair or replace only the components that were found to be out of specification.
Refer to OEM Service Manual
Validation
- Connect all components
- Connect the recommended Cummins electronic service tool or equivalent.
- Disable the fault code.
- Operate the engine within the “Conditions for Clearing the Fault Code” found in the Overview section of the troubleshooting procedure.
- Verify that the fault code is no longer active.
- Check ECM Calibration Revision History
- Use the recommended Cummins electronic service tool or equivalent to find the current ECM code and revision number in the ECM.
- Compare the ECM code and revision number in the ECM to the calibration revisions listed in the ECM Calibration Revision History Database for applicable changes related to this fault code.
- Refer to ECM Calibration Revision History Database.
Verification
Conditions
- Connect all components.
- Turn keyswitch ON.
- Connect the recommended Cummins electronic service tool or equivalent.
Action
- Use the recommended Cummins electronic service tool or equivalent to read the fault codes.
- Use the recommended Cummins electronic service tool or equivalent to find the current ECM code and revision number in the ECM.
- Compare the ECM code and revision number in the ECM to the calibration revision listed in the ECM calibration revision history for applicable changes.
Specification
- If a calibration update for this fault code is available, the ECM calibration revision must be that revision or higher.
Linked Solutions
- None
Repair
- Prior to downloading the ECM calibration, check to see that all job images and all other troubleshooting has been documented as downloading an ECM calibration will remove the fault codes on the ECM.
- Download the updated ECM calibration code.
Validation
- Connect all components
- Connect the recommended Cummins electronic service tool or equivalent.
- Disable the fault code.
- Operate the engine within the “Conditions for Clearing the Fault Code” found in the Overview section of the troubleshooting procedure.
- Verify that the fault code is no longer active.
- Check ECM Calibration Revision History
- Use the recommended Cummins electronic service tool or equivalent to find the current ECM code and revision number in the ECM.
- Compare the ECM code and revision number in the ECM to the calibration revisions listed in the ECM Calibration Revision History Database for applicable changes related to this fault code.
- Refer to ECM Calibration Revision History Database.
If all steps have been completed and no root cause has been identified, then follow the technical escalation process.