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| Illustration 1 | g02731146 |
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Schematic of the "Left Final Drive Pressure" sensor | |
This diagnostic code is associated with the "Left Final Drive Pressure" sensor. The FMI 04 diagnostic code means that the Brake ECM has determined that the voltage of the circuit for the position sensor is below normal.
The pressure sensor is a PWM sensor that uses a frequency of the approximately 500 Hz. The duty cycle operates from a range of 10% to 90%.
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 Brake ECM has failed. This situation is unlikely.
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. Ensure that the diagnostic code of CID 3021 FMI 04 is active before performing this procedure.
Note: Use the 146-4080 Digital Multimeter for the measurements in this procedure.
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When it is necessary to work under the machine with the body (bed) raised, attach the body (bed) retaining cables to the rear tow points. Install the rear tow point pins through the ends of the retaining cables. Failure to properly secure the body (bed) may result in personal injury or death. |
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 3021 FMI 04 diagnostic code remains active.
Results:
- OK - The diagnostic code remains active. The sensor is correct. Proceed to Test Step 2.
- NOT OK - The diagnostic code is no longer active. The sensor has failed.
Repair: Replace the sensor.
STOP
Test Step 2. CHECK THE WIRING HARNESS OF THE SENSOR FOR A SHORT TO GROUND.
- Turn the key start switch and the disconnect switch to the OFF position.
- Disconnect the machine harness from the sensor.
- Disconnect the machine harness connectors from the ECM.
- At the machine harness connector for the ECM, measure the resistance from the signal contact J2-43 (wire H919-OR(Orange)) of the machine harness to all possible sources of ground. Measure the resistance to all contacts of the machine harness connectors for the Brake ECM.
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 not correct. There is a short in the machine harness.
Repair: The short is between signal contact J2-43 (wire H919-OR(Orange)) and the circuit with the low resistance measurement. Repair or replace the machine harness.
STOP
Test Step 3. CHECK IF THE DIAGNOSTIC CODE REMAINS.
- Inspect the contacts of the harness connectors and clean the contacts.
- Reconnect all harness connectors.
- Turn the disconnect switch and the key start switch to the ON position.
- Operate the machine.
- Check the status of the CID 3021 FMI 04 diagnostic code.
Expected Result:
The CID 3021 FMI 04 diagnostic code is active.
Results:
- YES - The CID 3021 FMI 04 diagnostic code is active. The diagnostic code has not been corrected. The ECM may have failed.
Repair: A failure of the Brake ECM is unlikely. Exit this procedure and perform this procedure again. Prior to replacing an ECM, always contact the Technical Communicator at your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM requires replacement, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".
STOP
- NO - The CID 3021 FMI 04 diagnostic code is not active. The diagnostic code does not exist at this time.
Repair: The initial diagnostic code was probably caused by a poor electrical connection or a short at one of the harness connectors. Resume normal machine operation.
STOP