824H Wheel Dozer, 825H Soil Compactor and 826H Landfill Compactor Electrohydraulic System Caterpillar

Illustration 1	g01157081
Schematic for the Cat Data Link circuit

This diagnostic code is recorded when the implement ECM cannot communicate with the Caterpillar Monitoring System via the Cat Data Link. The update rate from the ECM is not correct.

The possible causes for this diagnostic code are listed:

• The software for the modules is not compatible.

• The data link circuit has an open in the machine harness between the implement ECM and the Caterpillar Monitoring System.

• The data link circuit is shorted to ground.

• The data link circuit is shorted to +battery.

• The Caterpillar Monitoring System is faulty. This is unlikely.

System Response:

The machine response is listed:

• When the key switch is turned to the ON position, the implements will be disabled for ten seconds. The implement ECM waits for communication. After the communication is established, the implements will be enabled. If the ECM was never powered up with the proper communications between the implement ECM and the Caterpillar Monitoring System, the implements will remain disabled. This is true only if the ECM has never been powered up.

Note: Ensure that the diagnostic code is active.

Test Step 1. CHECK THE COMPATIBILITY OF THE SOFTWARE

1. For the correct software part numbers, refer to the Electronics Groups in the parts manual for the machine that is being serviced.

Expected Result:

The software is compatible.

Results:

• YES - The software is compatible. Proceed to Test Step 2.

• NO - The software is not compatible.

  Repair: Install the correct software. If any modules have been replaced, ensure that the correct part number was used.

  Stop.

Test Step 2. CHECK THE CAT DATA LINK FOR AN OPEN CIRCUIT

1. The disconnect switch remains in the OFF position.

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

3. At the machine harness J1 connector for the monitoring system, place a jumper wire from contact J1-14 (wire 945-BR) to connector contact J1-5 (944-OR).

4. At the implement ECM, measure the resistance between contact J1-3 (wire 945-BR) and contact J1-9 (944-OR).

Expected Result:

The resistance measurement is less than 5 ohms.

Results:

• YES - The resistance measurement is less than 5 ohms.

  Repair: The Cat Data Link circuit in the harness is correct.

  Proceed to Test Step 3.

• NO - The resistance measurement is greater than 5 ohms. A measurement that is more than 5 ohms and less than 5000 ohms could indicate that there is a faulty data link connection in the machine harness between the implement ECM and the Cat Monitoring System.

  Repair: Refer to the electrical system schematic for your machine. Ensure that all machine harness connectors are clean and in good condition. Repair the harness or replace the harness.

  Stop.

Test Step 3. CHECK FOR A CAT DATA LINK CIRCUIT SHORT TO GROUND

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

2. Turn the disconnect switch to the OFF position.

3. Disconnect the harness from all modules.

4. Inspect the harness connectors that are involved with the Cat Data Link circuit. Ensure that the connector contacts are clean and that the connectors are tight. If necessary, repair the connectors or replace the connectors.

5. Measure the resistance between the data link and all possible sources of ground at the harness connector for the ECM. The Cat Data Link connectors are J1-3 (wire 945-BR) and contact J1-9 (wire 944-OR). The following contacts are sources of ECM ground and frame ground:J1-2, J1-5, J1-7, J1-15, J1-16 and J2-3.

Expected Result:

The resistance is greater than 5000 ohms for each measurement.

Results:

• YES - The resistance is greater than 5000 ohms for each measurement. The harness is correct. Proceed to Test Step 4.

• NO - The resistance is less than 5000 ohms for each measurement.

  Repair: A resistance measurement that is less than 5000 ohms indicates that a short is present with another circuit in the wiring harness. The short is between the circuit with the resistance that is less than 5000 ohms and wire 945-BR or wire 944-OR). Repair the harness or replace the harness.

  Stop.

Test Step 4. CHECK FOR A CAT DATA LINK CIRCUIT SHORT TO POSITIVE VOLTAGE.

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

2. All the modules remain disconnected from the harness.

3. Measure the resistance between the data link connections and all possible sources of positive voltage at the harness connector for the ECM. The data link contacts are J1-3 (wire 945-BR) and contact J1-9 (wire 944-OR).

Expected Result:

Each resistance measurement is more than 5000 ohms.

Results:

• YES - The resistance is more than 5000 ohms. The harness is correct. Proceed to Test Step 5.

• NO - The resistance is less than 5000 ohms. A resistance measurement that is less than 5000 ohms indicates that a short is present with another circuit in the wiring harness. The short is between the circuit with the resistance that is less than 5000 ohms and connector contact J1-3 (wire 945-BR) or connector contact J1-9 (944-OR).

  Repair: Repair the harness or replace the harness.

  Stop.

Test Step 5. CHECK THE STATUS OF THE DIAGNOSTIC CODE

1. Inspect the contacts of the harness connectors that are used in the data link circuit. Ensure that the contacts are secure. Clean all of the contacts in the harness connectors.

2. Reconnect all harness connectors.

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

4. Operate the machine.

5. Check the status of the CID 0562 FMI 09.

Expected Result:

The CID 0562 FMI 06 diagnostic code is active.

Results:

• YES - The CID 0562 FMI 09 code is active. The diagnostic code has not been corrected. The Caterpillar Monitoring System may have failed.

  Repair: It is unlikely that the Caterpillar Monitoring System has failed. Exit this procedure and perform this procedure again. Refer to the full machine electrical system schematic. Ensure that all connections in the data link circuit are intact, clean and secure. If the cause of the diagnostic code is not found, replace the Caterpillar Monitoring System.

  Stop.

• NO - The CID 0562 FMI 09 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.