950K and 962K Wheel Loaders Electrohydraulic System Caterpillar

Illustration 1	g02686579
Connections of the Backlight Control circuit

This diagnostic code is associated with the Backlight Control circuit. The backlight lamps are used in the wiper panel, HVAC panel, front/rear washer switch, ATC/manual switch, implement lockout switch, parking brake switch and powered mirrors switch. The FMI 03 means that the Implement ECM has determined that the voltage of the backlight control circuit is above normal.

The possible causes of this diagnostic code are listed below:

• There is an open in the control circuit.

• The control circuit is shorted to another voltage source.

• The backlight lamp assembly 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 original diagnostic code has been corrected.

Test Step 1. CHECK THE CONTROL CIRCUIT FOR AN OPEN CIRCUIT

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

2. Disconnect the machine harness connectors from the switches and panels mentioned above.

3. At the machine harness connector for wiper panel, connect a jumper wire from the signal contact 1 (wire 600-BR(Brown)) to frame ground.

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

5. Observe the status of the active CID 1052 FMI 03 diagnostic code.

Expected Result:

The active CID 1052 FMI 03 diagnostic code is no longer active. A CID 1052 FMI 04 diagnostic code becomes active when the signal wire is grounded.

Results:

• YES - The active CID 1052 FMI 03 diagnostic code is no longer active. A CID 1052 FMI 04 diagnostic code has been activated after the signal wire is grounded. Proceed to Test Step 2.

• NO - The CID 1052 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 2. CHECK THE SIGNAL CIRCUIT FOR A SHORT

The machine harness connector remains disconnected from the associated panels. The key start switch and the disconnect switch remain in the OFF position.

1. Remove the jumper wire that was installed in the previous step.

2. Disconnect the machine harness connectors J1 and J2 from the ECM.

3. At the machine harness connector for the ECM, measure the resistance from the signal contact J1-67 (wire 600-BR(Brown)) to all of the other contacts that are used in the machine harness connectors for the Machine ECM.

Expected Result:

Each resistance measurement is greater than 5000 ohms.

Results:

• OK - Each resistance measurement is greater than 5000 ohms. The machine harness is correct. Proceed to Test Step 3.

• NOT OK - One or more resistance measurements are not correct. There is a short in the machine harness.

  Repair: The short is between the signal circuit 600-BR(Brown) and the circuit with the low resistance measurement. Repair the machine harness or replace the machine harness.

  STOP

Test Step 3. CHECK OPERATION OF THE ECM

The machine harness connector remains disconnected from the panels. The key start switch and the disconnect switch remain in the OFF position. The machine harness connectors remain disconnected from the ECM.

1. At the disconnected machine harness connector of the Implement ECM J1, use a 151-6320 Removal Tool to remove the signal wire 600-BR(Brown) and the socket at contact J1-67 from the J1 connector.

2. Reconnect the machine harness connectors J1 and J2 to the ECM.

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

4. Use a 7X-1710 Multimeter Probe that is disconnected from a multimeter to contact the ECM pin J1-67 through the empty space in the J1 connector.

5. Observe the status of the active CID 1052 FMI 03 diagnostic code. Ground the other end of the 7X-1710 Multimeter Probe to ground location on the frame of the machine.

Expected Result:

The active CID 1052 FMI 03 diagnostic code is no longer active. A CID 1052 FMI 04 diagnostic code becomes active when the ECM pin at J1-67 is grounded.

Results:

• YES - The CID 1052 FMI 03 diagnostic code is no longer active. A CID 1052 FMI 04 diagnostic code has been activated after the ECM pin is grounded. The ECM has responded correctly to the grounded circuit condition in the signal circuit. The ECM is most likely not causing the problem. Reconnect the signal wire and the socket in the machine harness connector J1 for the ECM before proceeding to the next test step. Proceed to Test Step 4.

• NO - The CID 1052 FMI 03 diagnostic code remains active. The status of the active diagnostic code does not change when the ECM pin for the backlight control is grounded.

  Repair: Reconnect the signal wire and the socket in the machine harness connector J1 for the ECM. Repeat this test step in order to verify that the ECM is the cause of the problem.

  If the CID 1052 FMI 03 diagnostic code is still active, the Implement ECM has failed.

  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 ECM requires replacement, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  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 on each of the wires that are associated with the 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. Operate the machine.

6. Check the status of the CID 1052 FMI 03 diagnostic code.

Expected Result:

The CID 1052 FMI 03 diagnostic code is active.

Results:

• YES - The CID 1052 FMI 03 diagnostic code is active. The problem has not been corrected.

  Repair: If available, perform a Wiggle Test on the signal circuit of the machine wiring harness with the Caterpillar Electronic Technician (CAT ET). The Wiggle Test can be used to detect the following in the machine wiring harness:

  • Momentary shorts

  • Opens
  If the cause of the problem is not found, replace the appropriate backlight assembly. After the backlight is replaced, perform this test step again. If the problem is still present after replacement of the backlight, the ECM may have failed.

  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 ECM that has activated the diagnostic code. See the Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  STOP

• NO - The CID 1052 FMI 03 diagnostic code is not active. The diagnostic code does not exist at this time.

  Repair: The initial diagnostic code was probably caused by a poor electrical connection at one of the harness connectors that was disconnected and reconnected. Resume normal machine operation.

  STOP