950K and 962K Wheel Loaders Electrohydraulic System Caterpillar

Illustration 1	g02442696
(1) Attachment two lever implement controls with auxiliary third function lever

Illustration 2	g02652900
Connections of the Third Auxiliary Lever Position Sensor

This diagnostic code is recorded when the ECM reads the input signal from the Third Auxiliary Lever Position Sensor and the voltage is above normal. The sensor is located in the implement control lever.

The duty cycle of the PWM sensor input signal will change according to the amount of lever movement on the forward / rearward axis. The position sensor signal operates at approximately 500 ± 100 Hz.

The lever position sensor is supplied system voltage through the right column, fuse F39 in the switched upper fuse panel (10A - circuit 146-GY). The sensor is supplied an ECM ground circuit (C214-BK) connection to the Implement ECM J1-70 contact.

This ground circuit is used for ECM location code ground connections and for ground supply connections. Most of the switches and sensors that are connected to the ECM also use this ground circuit.

The following table indicates the PWM duty cycles that the ECM will consider as acceptable in the indicated standard lever and auxiliary lever positions.

The Implement ECM will activate an FMI 03 diagnostic code for a specific lever when the duty cycle is greater than 96%.

The possible causes of this diagnostic code are listed:

• 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 the sensor power supply.

• 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 can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, that all connections are secure and that all connections are 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.

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 POWER SUPPLY OF THE SENSOR CIRCUIT

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

2. At the C4 harness connector for the implement control lever, insert 7X-1710 Multimeter Probes along the power supply contact 1 (wire 146-GY(Grey)) and along ground 2 contact J1-4 (wire X800-OR(Orange)).

3. Do not disconnect the machine harness from the C4 connector.

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

5. With a multimeter probe still connected to system power, measure the voltage at a known good frame ground.

Expected Result:

Both voltage measurements are approximately +battery voltage.

Results:

• OK - Both voltage measurements are approximately +battery voltage. The power supply for the sensor is correct. Proceed to Test Step 2.

• NOT OK - If both voltage measurements are less than +battery voltage, the power supply circuit is most likely causing the problem.

  Repair: An interruption of the power circuit will cause multiple diagnostic codes to activate for sensors that are powered from the fuse.

  Verify that the fuse is not open. Check the harness for opens or for poor connections in the power circuit.

  Refer to the complete Electrical System Schematic of the machine. Examine all of the connectors that are in the circuits. Ensure that the connections are clean, that all connections are secure and that all connections are in good condition.

  Repair or replace the faulty power supply circuit.

  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 C4 from the implement control lever assembly. At the harness connector, place a jumper wire between the signal contact 3 (wire H722-GN(Green)) 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 0487 FMI 03 diagnostic code.

Expected Result:

The active diagnostic code CID 0487 FMI 03 is no longer active. A CID 0487 FMI 04 diagnostic code becomes active when the signal wire (H722-GN(Green)) is grounded.

Results:

• YES - The active diagnostic code CID 0487 FMI 03 is no longer active. A CID 0487 FMI 04 diagnostic code has been activated after the signal wire is grounded. The ECM has correctly detected the grounded condition. The signal circuit is moat likely not open. Proceed to Test Step 3.

• NO - The CID 0487 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. If a problem is found in the harness, repair or replace the machine harness.

  If a problem is not found in the harness, proceed to Test Step 5.

  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 that was installed in the last step.

2. At the J2 machine harness connector for the ECM, measure the resistance from the sensor signal contact J2-26 (wire H722-GN(Green)) to all of the other J1 and J2 contacts that are used 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 resistance measurements do not indicate a short in the circuit. 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 signal circuit and the circuit with the low resistance measurement.

  Refer to the complete Electrical System Schematic of the machine. Check all of the connectors that are in the sensor circuit. Ensure that all connections are clean, that all connections are secure and that all connections are in good condition.

  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

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

1. Inspect all of the harness connectors for the lever and the ECM. Clean the contacts of the harness connectors and check the wires for damage to the insulation. Reconnect all harness connectors. Make sure that the connectors are fully seated and locked.

2. At the machine harness connector C4 for the implement control lever, use a 151-6320 Removal Tool to remove the signal wire H722-GN(Green) and the socket at contact 3 from the harness connector. The machine harness connector C4 remains connected to the implement control lever.

3. At the back of the connector C4 of the lever, insert 7X-1710 Multimeter Probes along the ground contact 2 and the signal contact 3.

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

5. Measure the duty cycle of the sensor at the connector pins of the steering control between the contacts 2 and 3. Move the lever through the full range of the sensor that is described at the beginning of this procedure.

Expected Result:

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

Results:

• OK - The duty cycle of the sensor is correct. The sensor is not the cause of the problem. Reconnect the signal wire and the socket in the machine harness connector for the lever. Proceed to Test Step 5.

• NOT OK - The duty cycle of the sensor is not correct according to the description at the beginning of this procedure. The sensor has failed.

  Repair: Perform this test step again in order to verify that the sensor signal is not correct.

  If the position sensor is not correct according to the description at the beginning of this procedure, replace the implement control lever 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. Inspect the harness connectors. Clean the contacts of the harness connectors. Check the wires for damage to the insulation 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. Make sure that the connectors are fully seated. Observe that the clips for each connector are fastened.

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

5. Operate the machine.

6. Determine if the CID 0487 FMI 03 diagnostic code is active.

Expected Result:

The CID 0487 FMI 03 diagnostic code is not active.

Results:

• OK - The CID 0487 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 0487 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 ECM that has activated this diagnostic code may have failed.

  Exit this procedure and perform this procedure again. If the cause of the failure is not found, contact the Technical Communicator at your dealership for possible consultation with Caterpillar. This consultation may effect repair time.

  If the ECM must be replaced, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  STOP