Conditions Which Generate This Code:
Schematic of the Left Joystick Position Sensor
This diagnostic code is associated with the Left/Right Position Sensor of the Left Joystick base. Each sensor provides an input signal to the ECM. This diagnostic code is recorded when the ECM reads the signal from the sensor and the voltage of the signal is below normal.
The position sensor is a PWM sensor that operates at a frequency of approximately 500 ± 80 hz. The position sensor sends a PWM input signal to the Machine ECM. The duty cycle of the signal will vary from approximately 20% at the joystick full left position to approximately 80% at the joystick full right position. When the joystick is in the center position, the duty cycle will be approximately 50%.
The possible causes of this diagnostic code are listed:
- The signal circuit is shorted to ground.
- The sensor has failed.
- The ECM has failed. ECM failure is unlikely.
Note: Ensure that CID 2476 FMI 04 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 problem has been corrected.
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, secure and 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.
The action lamp will flash. If the machine is configured in the 'H' pattern, the implement lift circuit will be disabled. If the machine is configured in the 'ISO' pattern, the machine will be brought to a stop. The park brake will be engaged.
Test Step 1. CHECK THE SENSOR
- Turn the key start switch to the ON position.
- Disconnect the machine harness connector from the left joystick. Observe the status of the diagnostic code.
The FMI 04 diagnostic code will remain active if the sensor is not the cause of the problem. The sensor is internally shorted if the FMI 04 diagnostic code is NO longer active.
- OK - The FMI 04 diagnostic code remains active. The sensor has not failed. Proceed to Test Step 2.
- NOT OK - The FMI 04 diagnostic code is NO longer active. The machine harness and the ECM are operating correctly.
Repair: The sensor operation is faulty. Replace the left joystick assembly. After replacement of the joystick assembly, verify that the operation of the new joystick assembly is correct before operating the machine.
Test Step 2. CHECK THE SIGNAL CIRCUIT FOR A SHORT TO GROUND
- The joystick connector remains disconnected from the machine harness.
- Disconnect the negative battery cable and turn the key start switch to the OFF position.
- Disconnect the J1 and J2 machine harness connectors from the Machine ECM.
- At machine harness connector for the Machine ECM, measure the resistance from contact J1-80 (wire E847-GY) to frame ground and measure the resistance to all of the other J1 and J2 contacts that are used for the Machine ECM.
Each resistance measurement is greater than 5000 ohms.
- OK - Each resistance measurement is greater than 5000 ohms. The machine harness is correct. Proceed to Test Step 3.
- NOT OK - One or more of the resistance measurements is NOT correct. The machine harness has failed.
Repair: There is a short in the machine harness between the signal circuit and the circuit with the low resistance measurement. Repair or replace the machine harness.
Test Step 3. CHECK THE STATUS OF THE DIAGNOSTIC CODE
- Inspect the harness connectors and clean the contacts of the harness connectors. Check the wires for damage to the insulation that is caused by excessive heat, battery acid, or chafing.
- Perform a 45 N (10 lb) pull test on each of the wires that are associated with the sensor circuit.
- Reconnect all harness connectors. Make sure that the connectors are fully seated and the clips for each connector are fastened completely.
- Reconnect the negative battery cable and turn the key start switch to the ON position.
- Operate the machine.
- Determine if the CID 2476 FMI 04 diagnostic code is active.
The CID 2476 FMI 04 diagnostic code is not active.
- OK - The CID 2476 FMI 04 diagnostic code is not active. The diagnostic code does not exist at this time. The initial diagnostic code was probably caused by a poor connection or a short at one of the connectors that was disconnected and reconnected. Resume normal operation STOP
- NOT OK - The CID 2476 FMI 04 diagnostic code is active. The diagnostic code has not been corrected.
Repair: Check the circuit again. Use Caterpillar Electronic Technician (Cat® ET), if available, and perform a "Wiggle Test" on the machine wiring harness. The wiggle test can detect momentary or intermittent shorts or opens in the machine wiring harness.ECM failure is unlikely. Perform this procedure again.
If the cause of the diagnostic code is not found, contact your dealer Technical Communicator (TC) 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".