EDGE-CUTTING 4T8077 - Caterpillar

Illustration 1 g00596060
Schematic For Temperature Sensor (Engine Coolant)The EMCP II monitors the engine coolant temperature in order to protect the engine in case of a problem with the coolant temperature. The temperature sensor is mounted in the water jacket toward the front of the engine. The exact location of the engine coolant temperature sensor depends 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 90 Hz. As temperature changes, the duty cycle of the signal varies from 10% to 95%. A temperature of -40 °C (-40 °F) is approximately 10% of the duty cycle. A temperature of 135 °C (275 °F) is approximately 93% of the duty cycle.Note: The GSC is usually programmed to treat a diagnostic code with the temperature sensor as an alarm fault (P04 = 0). If the GSC is programmed to treat a fault with the temperature sensor as a shutdown fault (P04 = 1), then diagnostic codes are automatically shown on the upper display.Note: Faults are created when the harness connector (40 contact) is disconnected from the GSC during these troubleshooting procedures. Clear these created faults after the particular fault is corrected. In a properly operating system, when the harness connector is removed from the GSC, the following diagnostic codes are recorded.
CID 100 FMI 3 pressure sensor (engine oil)
CID 110 FMI 3 temperature sensor (engine coolant)
CID 111 FMI 3 fluid level sensor (engine coolant)
CID 190 FMI 3 speed sensor (engine)
CID 331 FMI 2 switch (engine control)
CID 336 FMI 2 switch (engine control)ProcedureThis diagnostic code can be caused by the following conditions:
There is a short to the +battery of the sensor signal.
There is an open circuit of the sensor signal.Begin performing these procedures only when CID 110 FMI 3 is showing and the "DIAG" indicator is FLASHING on the upper display. The GSC treats a CID 110 FMI 3 as an alarm fault. Active alarm faults are shown on the display when the alarm codes key is pressed and the ECS is 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 CID 269 is active, then correct the diagnostic code prior to proceeding with this procedure.
Check the circuit for the supply.
Turn the ECS to OFF/RESET and then turn the ECS to the STOP position.
Disconnect the sensor from the engine harness. The sensor remains fastened to the engine.
At the side of the engine harness on the sensor connector, measure the voltage (DCV) between contact "A" (supply) and contact "B" (sensor ground). Expected Result: The voltage should be 8.0 0.5 DCV. Results:
OK - The supply circuit functions properly. Proceed to 2.
NOT OK - The supply circuit is faulty. Check the upper