834G Wheel Dozer and 836G Landfill Compactor Electrohydraulic System Caterpillar

Illustration 1	g01961041
Schematic of the Cat data link

This diagnostic code is recorded when the Implement ECM can not communicate with the Power Train ECM. The Implement ECM and the Power Train ECM communicate via the Cat Data Link.

The possible causes for this diagnostic code are listed:

• The data link wire has failed.

• The Implement ECM and the Power Train ECM are mismatched.

System Response:

The machine response is listed:

• Implements may not be locked out when the engine is being started.

• Calibrations for the implement valve will not work due to unavailable parking brake status.

• Calibrations for the linkage position will not work due to unavailable parking brake status.

Note: Ensure that the diagnostic code indicator is active and that the diagnostic code is active.

Test Step 1. VERIFY THE HARDWARE AND THE SOFTWARE PART NUMBERS

1. Verify that the following information is correct:
   • The part number of the flash software for the Implement ECM

   • The part number of the flash software for the Power Train ECM

   • The part number of the Implement ECM

   • The part number of the Power Train ECM

   Note: Consult your Caterpillar Dealer for the correct part numbers of the flash software.

Expected Result:

All of the part numbers are correct.

Results:

• OK - All of the part numbers are correct. Proceed to Test Step 2.

• NOT OK - All of the part numbers are not correct.

  Repair: The installed Implement ECM or the Power Train ECM have the wrong part number or the incorrect flash software is installed. Replace the incorrect Implement ECM or the Power Train ECM with a module that has the correct part number. Flash the correct software. See the Testing and Adjusting, "Electronic Control Module (ECM)-Flash Programming" Story in this manual for additional information.

  STOP

Test Step 2. INSPECT THE HARNESS CONNECTIONS

1. Turn the disconnect switch to the OFF position.

2. Inspect all harness connections that are related to the Cat 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 3.

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

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

  STOP

Test Step 3. 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 Cat Data Link.

3. At the machine harness for the Implement ECM, measure the resistance between frame ground and connector contacts J1-9 (wire 893-GN) and J1-3 (wire 892-BR) of the Cat 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 4.

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

  Repair: There is a short between frame ground and contacts J1-9 (wire 893-GN) and J1-3 (wire 892-BR) of the Cat data link circuit in the machine harness. Repair the machine harness or replace the machine harness.

  STOP

Test Step 4. CHECK FOR SHORT TO THE +BATTERY CIRCUIT

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

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

3. At the machine harness connector for the Implement ECM, perform the checks that are listed below:
   • Measure the resistance between the connector contact J1-1 (wire 146-GY) and connector contact J1-9 (wire 893-GN).

   • Measure the resistance between connector contact J1-1 (wire 146-GY) and connector contact J1-3 (wire 892-BR).

Expected Result:

The resistance is greater than 5000 ohms.

Results:

• OK - The harness circuit resistance is correct. Proceed to Test Step 5.

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

  Repair: There is a short between the +battery circuit and contacts J1-9 (wire 893-GN) and J1-3 (wire 892-BR) of the Cat data link circuit in the machine harness. Repair the machine harness or replace the machine harness.

  STOP

Test Step 5. 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 Cat Data Link circuit in the machine harness:
   • Measure the resistance between connector contact J1-9 (wire 893-GN) of the Implement ECM and connector contact J1-9 (wire 893-GN) of the power train ECM.

   • Measure the resistance between connector contact J1-3 (wire 892-BR) of the Implement ECM and connector contact J1-3 (wire 892-BR) of the Power Train ECM.

Expected Result:

The resistance measures less than 5 ohms.

Results:

• OK - The resistance is less than 5 ohms. The Cat Data Link circuit in the machine harness is correct. Proceed to Test Step 6.

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

  Repair: The Cat Data Link circuit is open in the machine harness. Repair the machine harness or replace the machine harness.

  STOP

Test Step 6. 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 Cat 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 Power Train ECM has failed.

  Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. If the failure is not found, replace the ECM.

  STOP

• NOT OK - Diagnostic codes are present for the other electronic control modules. The Implement ECM has failed.

  Repair: It is unlikely that the ECM has failed. Exit this procedure. Perform this procedure again. If the failure is not found, replace the ECM. See the Testing and Adjusting, "Electronic Control Module - Replace" Story in this manual.

  STOP