PLUNGER 6B8917 - Caterpillar

Illustration 1 g02476029
Connections of the Cab Ventilation Duct Temperature Sensor
This diagnostic code is associated with the Cab Ventilation Duct Temperature Sensor. The FMI 04 means that the Implement ECM has determined that the voltage of the sensor signal circuit is below normal. The Relay Driver Module communicates the information for this diagnostic code via CAN Datalink.The sensor resistance range is 33,650 ohms at −40° C (−40° F) to 18.6 ohms at 150° C (312° F). The possible causes of this diagnostic code are listed below:
The signal circuit for the sensor is shorted to ground.
The sensor has failed.
The Relay Driver Module has failed. This condition is unlikely. Note: Before performing this procedure, inspect the harness connectors that are involved in the circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, that all connections are secure and that all connections are in good condition. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing this procedure. Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the original diagnostic code has been corrected. Test Step 1. CHECK THE SENSOR
Turn the disconnect switch and the key start switch to the ON position.
Ensure that the diagnostic code is active.
Observe the status of the diagnostic code. Disconnect the sensor from the machine harness. Expected Result:The CID 2663 FMI 04 diagnostic code changes to a CID 2663 FMI 03 diagnostic code when the sensor is disconnected from the machine harness.Results:
YES - The CID 2663 FMI 04 diagnostic code changes to a CID 2663 FMI 03 diagnostic code when the sensor is disconnected. The sensor has failed.Repair: The sensor is causing the problem. Replace the temperature sensor.STOP
NO - Disconnecting the sensor from the machine harness did not change the status for the active diagnostic code. The CID 2663 FMI 04 diagnostic code is still active. The sensor is not causing the problem. Proceed to Test Step 2.Test Step 2. CHECK THE SENSOR CIRCUIT FOR A SHORTThe sensor remains disconnected from the machine harness.
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness connector J1 from the Relay Driver Module.
At the machine harness connector for the Relay Driver Module, measure the resistance from the signal contact J1-31 (wire E558-YL(Yellow)) to frame ground. Measure the resistance from the signal contact J1-31 (wire E558-YL(Yellow)) to all of the contacts that are used in the machine harness connectors for the Relay Driver Module. Expected Result:Each resistance measurement is greater than 5000 ohms.Results:
OK - Each resistance measurement is greater than 5000 ohms. The machine harness is correct. Proceed to Test Step 3.
NOT OK - One or more resistance measurements are less than 5000 ohms. There is a short in the machine harness.Repair: The short is between signal wire E558-YL(Yellow) and the circuit with the low resistance measurement.