CONTROL GP-INLET AIR 3551049 - Caterpillar

Illustration 1 g00527377
System Schematic For Engine Coolant Temperature Sensor (ECTS)The EMCP II system monitors the engine coolant temperature in order to protect the engine from a coolant temperature problem. The coolant temperature sensor is mounted in the water jacket. The exact location of the engine coolant temperature sensor varies depending on the engine model.The sensor is powered by an 8 volt sensor supply from the GSC. The coolant temperature signal is a pulse width modulated signal. The base frequency of the signal is 455 Hz (370 to 550 Hz). As temperature changes, the duty cycle of the signal varies from 10 to 95 percent.
-40°C (-40°F) is approximately 10% of the duty cycle. This is approximately 1.0 DCV.
135°C (275°F) is approximately 93% of the duty cycle.Note: The GSC is usually programmed to treat a coolant temperature sensor problem as an alarm fault. The factory default of P04 is 0. If the GSC is programmed to shutdown for a coolant temperature sensor fault, the operator is not required to press the "Alarm Codes" key in order to view the CID 110 FMI 4. The upper display automatically shows the CID 110 FMI 4.The possible cause of a CID 110 FMI 4 is provided below:
A short to the -battery of the sensor signal.Begin performing these procedures only when CID 110 FMI 4 is showing and the "DIAG" indicator is FLASHING on the upper display. The flashing indicator indicated that the diagnostic code is active. The GSC treats a CID 110 FMI 4 as an alarm fault. Active alarm faults are shown on the display when the "Alarm Codes" key is pressed. The engine control switch (ECS) must be in any position except the OFF/RESET position. For an inactive fault, the problem may be intermittent. To troubleshoot an inactive fault, use the preceding system schematic and see Testing And Adjusting, "Electrical Connector - Inspect". Clear the diagnostic code from the fault log after troubleshooting is complete.Note: If a CID 269 FMI 3 or a CID 269 FMI 4 is active, correct the sensor supply fault prior to proceeding with this procedure.Test Step 1. CHECK THE GSC AND THE HARNESS.
Make sure that CID 110 FMI 4 is showing on the display.
Turn the ECS to the OFF/RESET position.
Disconnect the sensor from the engine harness. The sensor remains fastened to the engine.
Turn the ECS to the STOP position.
Press the key.
Check if the CID 110 FMI 4 is not present. Check if the CID 110 FMI 3 is now showing.Expected Result:CID 110 FMI 4 is not showing. CID 110 FMI 4 is now inactive. CID 110 FMI 3 is now showing. CID 110 FMI 3 is now active.Results:
OK - The GSC and the harness function properly. Therefore, the sensor has failed. Replace the sensor. Repair: For more sensor testing information, refer to Testing and Adjusting, "Pulse Width Modulated (PWM) Sensor - Test". Stop.
NOT OK - The CID 110 FMI 4 is still showing. The harness or the GSC has failed. Proceed to Test Step 2.Test Step 2.