450E Backhoe Loader Caterpillar

Illustration 1	g01442149
Schematic of the CAN data link circuit

This diagnostic code is recorded when the Machine ECM stops receiving information on the CAN data link.

Note: The resistance of the CAN circuit wires should measure approximately 120 ohms between circuit components.

Test Step 1. INSPECT THE HARNESS CONNECTIONS.

1. Turn the disconnect switch to the OFF position.

2. Inspect all harness connections that are related to the CAN data link. Make sure that the connectors are clean and tight.

3. Check the connectors for proper mating. Ensure that all the seals are present and in place.

4. Check the harness for signs of damage or abrasion.

5. Check the wires at the connector. Ensure that the wires are secured tightly into the connector. Take care not to pull the wire out of the connector.

6. Check the exposed wires at the connectors for nicks or signs of abrasion.

7. Check for moisture inside the connector.

8. Check the connectors for dirty contacts or corroded contacts.

9. Check each pin and each socket of the machine harness connectors. Ensure that the contacts are properly installed. The contacts should mate correctly when the two pieces of the connector are placed together.

Expected Result:

The machine harness connectors are tight and free of corrosion.

Results:

• OK - The machine harness connectors are tight and free of corrosion. Proceed to Test Step 2.

• NOT OK - The machine harness connectors are in need of repair.

  Repair: Repair the machine harness or replace the machine harness.

  STOP

Test Step 2. CHECK FOR SHORTS TO GROUND

1. The disconnect switch remains in the OFF position.

2. Disconnect the machine harness connectors from all electronic control modules that use the CAN data link.

3. At the machine harness for the Machine ECM, measure the resistance between frame ground and connector contacts J2-67 (wire F711-GN) and J2-68 (wire F712-GY) of the data link circuit.

Expected Result:

The resistance is greater than 5000 ohms.

Results:

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

• NOT OK - The resistance is less than 5000 ohms. The machine harness has failed.

  Repair: There is a short between frame ground and contacts J2-67 (wire F711-GN) and J2-68 (wire F712-GY) of the data link circuit in the machine harness. Repair the machine harness or replace the machine harness.

  STOP

Test Step 3. CHECK FOR SHORT TO THE +BATTERY CIRCUIT

1. The disconnect switch remains in the OFF position.

2. All related electronic control modules remain disconnected from the machine harness.

3. At the machine harness connector for the Machine ECM, perform the checks that are listed here:
   • Measure the resistance between all of the connector contacts that are used at the Machine ECM, and connector contact J2-67 (wire F711-GN).

   • Measure the resistance between all of the connector contacts that are used at the Machine ECM, and connector contact J2-68 (wire F712-GY).

Expected Result:

Each of the resistance measurements is greater than 5000 ohms.

Results:

• OK - The harness circuit resistance is correct. Proceed to Test Step 4.

• NOT OK - One of the resistance measurements is less than 5000 ohms. The machine harness has failed.

  Repair: There is a short between the circuit with the low resistance measurement and contacts J2-67 (wire F711-GN) or J2-68 (wire F712-GY) of the data link circuit in the machine harness. Repair the machine harness or replace the machine harness.

  STOP

Test Step 4. CHECK FOR OPEN HARNESS

1. The disconnect switch remains in the OFF position.

2. All related electronic control modules remain disconnected from the machine harness.

3. Check the resistance of the data link circuit in the machine harness:
   • Measure the resistance between connector contact J2-67 (wire F711-GN) of the Machine ECM and the appropriate connector contact (wire F711-GN) of the other devices that are connected to the CAN data link.

   • Measure the resistance between connector contact J2-68 (wire F712-GY) of the Machine ECM and the appropriate connector contact (wire F712-GY) of the other devices that are connected to the CAN data link.

Expected Result:

Each resistance measurement is less than 5 ohms.

Results:

• OK - The resistance is less than 5 ohms. The data link circuit in the machine harness is correct. Proceed to Test Step 5.

• NOT OK - The resistance is greater than 5 ohms. The machine harness has failed.

  Repair: The data link circuit is open in the machine harness. Repair the machine harness or replace the machine harness.

  STOP

Test Step 5. CHECK FOR ADDITIONAL DIAGNOSTIC CODES FOR THE OTHER ELECTRONIC CONTROL MODULES.

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

2. One at a time, reconnect the electronic control modules that use the CAN data link.

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

4. After each of the electronic control modules has been reconnected, check for diagnostic codes that are logged against that electronic control module.

Expected Result:

Diagnostic codes are not present for the other electronic control modules.

Results:

• OK - Diagnostic codes are not present for the other electronic control modules. The dash panel cluster may have failed.

  Repair: Prior to replacing an ECM, always contact your dealership's Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM must be replaced, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  STOP

• NOT OK - Diagnostic codes are present for the other electronic control modules. The Machine ECM may have failed.

  Repair: Prior to replacing an ECM, always contact your dealership's Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM must be replaced, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  STOP