CM870 and ISX Engines – FAULT CODE 144

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Overview

Engine Coolant Temperature Sensor Circuit SMALL | MEDIUM | LARGE

Circuit Description

The engine coolant temperature sensor is used by the electronic control module (ECM) to monitor the engine coolant temperature. The ECM monitors the voltage on the signal pin, and converts this to a temperature value. The engine coolant temperature value is used by the ECM for the engine protection system, and engine emissions control.

Component Location

The engine coolant temperature sensor is located on the thermostat housing. Refer to Procedure 100-002 (Engine Diagrams) in Section E for a detailed component location view.

Shop Talk

Beginning with ESN 14039654, the temperature sensor return circuit was separated form the pressure sensor return circuit. For ESNs prior to this and with engine wiring harness Part Number 3682854, refer to the Common Pressure/Temperature Sensor Return Circuit above. For this ESN and greater or for any other engine wiring harness part number, refer to the Separate Pressure/Temperature Sensor Return Circuit above.

The engine coolant temperature sensor shares return wires in the engine harness with other sensors. An open return can cause multiple fault codes to be active. Before troubleshooting Fault Code 144, check for multiple fault codes.

Possible causes of this fault code include:

• Open return circuit in the harness, connectors, sensor, or ECM
• Open signal circuit or shorted to a voltage source.

Refer to Troubleshooting Fault Code t05-144