CM871 and CM876 Electronic Control Systems, ISX and ISM Engines – FAULT CODE 146

Engine Coolant Temperature – Data Valid but Above Normal Operational Range – Moderately Severe Level


Overview

CODE REASON EFFECT
Fault Code: 146
PID: P110
SPN: 110
FMI: 0/16
LAMP: Amber
SRT: 

Engine Coolant Temperature – Data Valid but Above Normal Operational Range – Moderately Severe Level. Engine coolant temperature is above engine protection warning limit.

Power derate and possible engine shutdown if Engine Protection Shutdown feature is enabled.

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 engine coolant. 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 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.
  • Exhaust gas recirculation (EGR) valve operation will be disabled.

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 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, calibrate the ECM again. Refer to Procedure 019-032 in Section 19 in the corresponding Troubleshooting and Repair Manual for the engine being serviced.

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 is failed unless there are other active coolant temperature sensor faults.

Refer to Engine Coolant Temperature Above Normal symptom troubleshooting tree.

  • For ISM engines, refer to the ISM, ISMe, and QSM11 Service Manual, Bulletin 3666322.
  • For ISX engines, refer to the Signature™, ISX, and QSX15 Service Manual, Bulletin 3666239.

Refer to Troubleshooting Fault Code t05-146

Last Modified:  09-Jul-2010