980K Wheel Loader Electrohydraulic System Caterpillar

Illustration 1	g02440816
Auxiliary Fourth Function electrical connections (dashed) that must be customer connected

Illustration 2	g02440817
Connections of Auxiliary Fourth Function (Thumbroller) Position Sensor

This diagnostic code is associated with the Auxiliary Fourth Function (Thumbroller) Position Sensor. The position sensor is located in the right joystick.

The Implement ECM 10 VDC sensor power supply and ground are used to power the sensor.

The Implement ECM will activate an FMI 03 diagnostic code when the duty cycle is greater than 93%.

The position sensor is a PWM sensor that operates at a frequency of approximately 500 ± 100 Hz. The position sensor sends a PWM input signal to the Implement ECM. The variations in the duty cycle of the signal follow:

The possible causes of this diagnostic code are listed below:

• The power supply circuit of the sensor is open.

• The return circuit of the sensor is open.

• The signal circuit is open.

• The signal circuit is shorted to another voltage source.

• The sensor has failed.

• The ECM has failed. This condition is unlikely.

Note: Before performing this procedure, inspect the harness connectors that are involved in the circuit. Poor connections are often the cause of a problem in an electrical circuit. Inspect the connections for the following:

• Connections are clean.

• Connections are secure.

• Connections are in good condition.

Note: 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 problem has been corrected.

Test Step 1. CHECK THE SENSOR POWER SUPPLY

1. Turn the key start switch and the disconnect switch to the ON position.

2. At the X-C1 harness connector for the right joystick, insert 7X-1710 Multimeter Probes along the contact for the power supply 1 (wire U727-YL(Yellow)) and along the ground contact 2 (wire J765-BU(Blue)). Do not disconnect the machine harness from the X-C1 connector.

3. Measure the DC voltage of the sensor power supply.

Expected Result:

The voltage measurement is approximately 10.0 ± 1.0 VDC.

Results:

• OK - The voltage measurement is approximately 10.0 ± 1.0 VDC. The power supply for the sensor is correct. Proceed to Test Step 2.

• NOT OK - The voltage measurement is less than 10.0 ± 1.0 VDC. The power supply for the sensor is not correct.

  Repair: Either the ground circuit wire for the sensor J765-BU(Blue) or the supply wire U727-YL(Yellow) has a bad connection or an open in the machine harness. Examine all of the connectors that are in the circuit. Inspect the connections for the following:

  • Connections are clean.

  • Connections are secure.

  • Connections are in good condition.
  Refer to the CID 1482 procedures in this manual for troubleshooting the power supply of 10 VDC. Repair the machine harness or replace the machine harness.

  STOP

Test Step 2. CHECK FOR AN OPEN IN THE SENSOR CIRCUIT

1. Turn the key start switch and the disconnect switch to the OFF position.

2. Disconnect the machine harness connector X-C1 from the right joystick. At the machine harness connector X-C1, connect a jumper wire between the signal contact 4 (wire G947-WH(White)) and frame ground.

3. Turn the key start switch and the disconnect switch to the ON position.

4. Observe the status of the active CID 2285 FMI 03 diagnostic code.

Expected Result:

The active diagnostic code CID 2285 FMI 03 is no longer active. A CID 2285 FMI 04 diagnostic code becomes active when the signal wire (G947-WH(White)) is grounded.

Results:

• YES - The active diagnostic code CID 2285 FMI 03 is no longer active. A CID 2285 FMI 04 diagnostic code has been activated after the signal wire is grounded. Proceed to Test Step 3.

• NO - The CID 2285 FMI 03 diagnostic code remains active. The status of the active diagnostic code does not change when the signal wire is grounded. There is an open or a poor connection in the signal wire.

  Repair: Check the signal circuit for an open or for a poor connection. Repair or replace the machine harness.

  STOP

Test Step 3. CHECK THE SIGNAL CIRCUIT FOR A SHORT

The key start switch and the disconnect switch remain in the OFF position.

1. Remove the jumper wire from the machine harness connector that was installed in the last test step.

2. Disconnect any J1 and J2 machine harness connectors that are not already disconnected from the Implement ECM.

3. At the J2 machine harness connector for the Implement ECM, measure the resistance from the signal contact of the sensor J2-26 (wire G947-WH(White)) to frame ground.

4. At the J2 connector for the machine harness of the Implement ECM, measure the resistance from the signal contact of the sensor J2-26 (wire G947-WH(White)) to all of the other J1 and J2 contacts that are used in the connectors for the Implement ECM.

Expected Result:

Each resistance measurement is greater than 5000 ohms.

Results:

• OK - Each resistance measurement is greater than 5000 ohms. The signal circuit is not shorted in the machine harness. Inspect the machine harness connectors. Clean the connectors for the Implement ECM. Reconnect the J1 and J2 harness connectors to the ECM module before proceeding to the next test step. Proceed to Test Step 4.

• NOT OK - A resistance measurement is less than 5000 ohms.

  Repair: There is a short in the machine harness. The short is between the wire of the signal circuit of the sensor G947-WH(White) and the circuit with the low resistance measurement. For information on testing for short circuits and finding short circuits, refer to Testing and Adjusting, "Wiring Harness (Short Circuit) - Test". Repair the machine harness or replace the machine harness.

  STOP

Test Step 4. CHECK THE SIGNAL AT THE SENSOR

1. The machine harness connectors are reconnected to the Implement ECM.

2. The key start switch and the disconnect switch remain in the OFF position.

3. At the machine harness connector X-C1 for the right joystick, use a 151-6320 Removal Tool to remove the signal wire G947-WH(White) and the socket at contact 4 from the harness connector. The machine harness connector X-C1 remains connected to the right joystick.

4. Turn the key start switch and the disconnect switch to the ON position.

5. At the connector X-C1 for the right joystick, insert a 7X-1710 Multimeter Probe along the return contact of the sensor 2 (wire J765-BU(Blue)).

6. Use the other multimeter probe to make contact through the harness connector with pin 4 for the position sensor on the joystick connector.

7. Measure the duty cycle of the sensor signal between the connector contacts 2 and 4 of the right joystick. Slowly move the thumbroller to the full forward position and observe the duty cycle of the sensor signal. Slowly move the thumbroller to the full rearward position and observe the duty cycle of the sensor signal.

Expected Result:

The duty cycle of the position sensor is correct according to the description at the beginning of this procedure.

Results:

• OK - The duty cycle of the sensor is correct. Reconnect the signal wire and the socket in the machine harness connector for the right joystick. Proceed to Test Step 5.

• NOT OK - The duty cycle of the position sensor is not within the acceptable duty cycle range. The sensor has failed.

  Repair: The operation of the position sensor is not correct. Replace the joystick assembly. After replacement, verify that the operation is correct before operating the machine.

  STOP

Test Step 5. CHECK THE STATUS OF THE DIAGNOSTIC CODE

1. Perform the following:

   • Visually inspect the harness connectors.

   • Clean the contacts of the harness connectors.

   • Visually inspect the insulation of the wires for damage that can be caused by excessive heat, battery acid, or chafing.

2. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the sensor circuit.

3. Reconnect all harness connectors. Verify the following:

   • The connectors are fully seated.

   • The clips for each connector are fastened completely.

4. Turn the disconnect switch and the key start switch to the ON position.

5. Operate the machine.

6. Determine if the CID 2285 FMI 03 diagnostic code is active.

Expected Result:

The CID 2285 FMI 03 diagnostic code is not active.

Results:

• OK - The CID 2285 FMI 03 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 2285 FMI 03 diagnostic code is active. The diagnostic code has not been corrected.

  Repair: If available, perform a Wiggle Test on the machine wiring harness with the Caterpillar Electronic Technician (Cat ET) service tool. The Wiggle Test can detect the following in the machine wiring harness:

  • Momentary shorts

  • Intermittent shorts

  • Opens
  If the cause of the active diagnostic code is not found, the Implement ECM may have failed.

  ECM failure is unlikely. Exit this procedure and perform this procedure again. If the cause of the failure is not found, replace the ECM. Prior to replacing an ECM, always contact the Technical Communicator at your dealership for possible consultation with Caterpillar. This consultation may effect repair time. If the cause of the diagnostic code is not found, replace the Implement ECM. Refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  STOP