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 Third 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 position sensor.

The ECM will activate an FMI 04 diagnostic code for a specific lever when the duty cycle is less than 7%.

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:

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. 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

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

2. Disconnect the machine harness connector X-C1 from the auxiliary control pod. Observe the status of the diagnostic code.

Expected Result:

The FMI 04 diagnostic code will remain active if the sensor is not the cause of the problem. The active FMI 04 diagnostic code changes to an active FMI 03 diagnostic code when the connector is disconnected. The sensor is likely causing the problem.

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• NOT OK - The FMI 04 diagnostic code is no longer active. An FMI 03 diagnostic code is active when the sensor is disconnected. The machine harness and the ECM are operating correctly.

  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 2. CHECK THE SIGNAL CIRCUIT FOR A SHORT TO GROUND

1. The connector J1 of the auxiliary control pod remains disconnected from the machine harness.

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

3. Disconnect the J1 and J2 machine harness connectors from the Implement ECM.

4. At the J2 machine harness connector for the Implement ECM, measure the resistance from the sensor signal contact J2-27 (wire G947-WH(White)) to frame ground.

5. Measure the resistance from the sensor signal contact J2-27 (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. Proceed to Test Step 3.

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

  Repair: There is a short in the machine harness. The short is between the signal circuit of the sensor (wire 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 3. 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 04 diagnostic code is active.

Expected Result:

The CID 2285 FMI 04 diagnostic code is not active.

Results:

• OK - The CID 2285 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 2285 FMI 04 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