CM871 and CM876 Electronic Control Systems, ISX and ISM Engines – FAULT CODE 2963

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Overview

ISX – Engine Coolant Temperature Sensor Circuit SMALL | MEDIUM | LARGE

ISM – Engine Coolant Temperature Sensor Circuit SMALL | MEDIUM | LARGE

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 electronic 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.

The engine coolant temperature value is used by the ECM for the engine protection system and for engine emissions control. This fault code indicates that the engine coolant temperature has exceeded the engine protection limit.

Component Location

The engine coolant temperature sensor is located on the exhaust side of the engine near the thermostat housing. Use the following procedure for a detailed component location view.Refer to Procedure 100-002 in Section E.

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 temperature is greater than a calibratible limit set in the ECM.

Action Taken When the Fault Code is Active

• The ECM logs the fault code immediately when the diagnostic runs and fails.
• The torque output of the engine will be reduced.

Conditions for Clearing the Fault Code

The ECM will turn off the fault code immediately after the coolant temperature decreases below the engine protection limit.

Shop Talk

Verify the 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, calibrate the ECM again. Refer to Procedure 019-032 in Section 19.

This fault code indicates that coolant temperature has exceeded the engine protection limits for high coolant temperature. It is highly unlikely that the coolant temperature sensor has malfunctioned unless there are other active coolant temperature sensor faults.

• For ISM engines, refer to the Engine Coolant Temperature Above Normal symptom tree in the ISM, ISMe and QSM11 Service Manual, Bulletin 3666322.
• For ISX engines refer to the Engine Coolant Temperature Above Normal symptom tree in the Signature™, ISX and QSX15 Service Manual, Bulletin 3666239.

Refer to Troubleshooting Fault Code t05-2963