LINK AS 1128923 - Caterpillar

Illustration 1 g01276393
Right Joystick Thumbwheel Position Sensor connectionsThis diagnostic code is associated with the Right Joystick Thumbwheel Position Sensor. The FMI 04 diagnostic code is activated when the Machine Control ECM detects that the voltage of the position sensor PWM input signal is below normal.The sensor is a PWM sensor that operates at a frequency of approximately 500 100 hertz. When the right thumbwheel is moved to the full left position, the sensor PWM duty cycle input to the ECM is 20 5 percent. When the right thumbwheel is moved to the full right position, the sensor PWM duty cycle input to the ECM is 80 5 percent. When the left thumbwheel is in the center position, the sensor PWM duty cycle input to the ECM is approximately 50 percent.The conditions that can cause this diagnostic code are listed:
The signal circuit is shorted to a ground source.
The sensor has failed.
The ECM has failed. This is unlikely. 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 the 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.System Response:When the CID 1658 FMI 04 diagnostic code is active, the multi-function auxiliary hydraulics system will be disabled.Test Step 1. CHECK THE SENSOR
Turn the disconnect switch and the key start switch to the ON position.
While observing the status of the diagnostic code, disconnect the machine harness connector from the right joystick thumbwheel position sensor.Expected Result: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 changes to an active FMI 03 diagnostic code when the sensor is disconnected from the machine harness.Results:
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 changes to an FMI 03 diagnostic code when the sensor is disconnected. The machine harness and the ECM are operating correctly.Repair: The Right Joystick Thumbwheel Position Sensor or a sensor component (wiring or connector) is causing the problem. Check and clean the sensor connector. Check the sensor connector contacts for short circuits. Check the sensor wiring harness for short circuits. Reconnect the sensor connector to the machine wiring harness and perform this test step again. If the sensor is determined to be causing the problem, the joystick will have to be replaced.The Thumbwheel Position Sensor is not serviceable. Replace the Right Joystick. After the joystick is replaced, verify that the new joystick corrected the problem before operating the machine.STOPTest Step 2. CHECK THE SIGNAL