950K and 962K Wheel Loaders Electrohydraulic System Caterpillar

Illustration 1	g02478153
Connections of the Rear Wiper Control Position Sensor

This diagnostic code is associated with the Rear Wiper Control Position Sensor. The FMI 03 diagnostic code is recorded when the Relay Driver Module reads the signal from sensor and the voltage is above normal. This diagnostic code is activated on the Implement ECM via CAN Datalink. The sensor is located internally to the wiper panel on a film.

The Rear Wiper Control Position Sensor is supplied voltage from the 8V supply from the Relay Driver Module.

The possible conditions that could cause this diagnostic code are:

• The power supply circuit of the sensor is open or has a poor connection.

• The return circuit of the sensor is open or has a poor connection.

• The signal circuit is open or has a poor connection.

• The signal circuit is shorted to another power supply.

• The Wiper Panel has failed.

• The Relay Driver Module has failed. This condition is unlikely.

Note: The correct operating temperature range for the sensor is −40 °C (−40.0 °F) to 85° C (185° F). When the environment of the cab is at extreme temperatures, an FMI 03 or an FMI 08 the diagnostic code may become active. Standardize the environment of the cab, in order to keep the sensors operating in the acceptable temperature range. After standardizing the temperature to normal, verify that the CID 2903 FMI 03 diagnostic code is active before performing this procedure.

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 harness connector for the wiper panel, insert 7X-1710 Multimeter Probes along the contacts of the power supply 3 (wire E774-GN(Green)) and along ground contact 6 (wire J851-BR(Brown)).

3. Do not disconnect the machine harness from the wiper panel connector.

4. Measure the DC voltage of the power supply.

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

Expected Result:

Both voltage measurements are approximately 8.0 ± 0.4 VDC.

Results:

• OK - Both voltage measurements are approximately 8.0 ± 0.4 VDC. The power supply for the sensor is correct. Proceed to Test Step 2.

• NOT OK - If both voltage measurements are less than 8.0 ± 0.4 VDC, the power supply circuit is most likely causing the problem.

  Repair: 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 from the wiper panel. At the harness connector, place a jumper wire between the signal contact 4 (wire 504-YL(Yellow)) 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 2903 FMI 03 diagnostic code.

Expected Result:

The active diagnostic code CID 2903 FMI 03 is no longer active. A CID 2903 FMI 04 diagnostic code becomes active when the signal wire (504-YL(Yellow)) is grounded.

Results:

• YES - The active diagnostic code CID 2903 FMI 03 is no longer active. A CID 2903 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 most likely not open. Proceed to Test Step 3.

• NO - The CID 2903 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. The wiper panel connector remains disconnected.

2. Disconnect the J1 machine harness connector for the Relay Driver Module.

3. At the J1 machine harness connector for the RDM, measure the resistance from the sensor signal contact J1-46 (wire 504-YL(Yellow)) to each of the other J1 circuits that are used for the Relay Driver Module.

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 to another circuit in the harness. 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 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 at the connectors that are used in the sensor circuit.

3. Reconnect all harness connectors. Make sure that the connectors are fully seated and locked.

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

5. Determine if the CID 2903 FMI 03 diagnostic code is active.

Expected Result:

The CID 2903 FMI 03 diagnostic code is not active.

Results:

• OK - The CID 2903 FMI 03 diagnostic code is not active. The diagnostic code does not exist at this time. The initial diagnostic code could have been 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 2903 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
  Verify that all possible causes have been investigated. If the RDM did not respond correctly to the grounded signal circuit, this diagnostic code may have been activated in error.

  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