PL61 Pipelayer and D6K Track-Type Tractor Caterpillar

SAE J1939 Data Link - Abnormal Update Rate

Illustration 1	g03235018
Schematic of the CAN A Data Link circuit (DHA1-885 and FBH1-1049)

Illustration 2	g03235272
Schematic of the CAN A Data Link circuit (DHA886-UP and FBH1050-UP)

This diagnostic code is recorded when the machine electronic control module (ECM) stops receiving expectant information on the CAN A data link. The CAN A data link is also known as the CJ1939 data link.

Note: The resistance of the CAN A circuit wires should measure approximately 60 ohms between circuit components.

Test Step 1. INSPECT THE HARNESS CONNECTIONS.

Note: Refer to Troubleshooting, "Electrical Connector - Inspect" in this manual.

1. Turn the disconnect switch to the OFF position.

2. Inspect all harness connections that are related to the CAN A 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 ECMs that use the CAN A data link.

3. At the machine harness for the machine ECM, measure the resistance between frame ground and connector contacts J2-56 and J2-67 (wire F711-GN) and J2-68 and J2-70 (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 J2-56, J2-67, J2-68 and J2-70 of the data link circuit in the machine harness. Repair 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 ECMs 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 contacts J2-56 and J2-67 (wire F711-GN).

   • Measure the resistance between all of the connector contacts that are used at the Machine ECM, and connector contacts J2-68 and J2-70 (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 J2-56 or J2-67 (wire F711-GN) or J2-68 or J2-70 (wire F712-GY) of the data link circuit in the machine harness. Repair or replace the machine harness.

  STOP

Test Step 4. CHECK FOR OPEN HARNESS

1. The disconnect switch remains in the OFF position.

2. Connect the machine ECM connector only. All other related ECMs 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 J2-56 or J2-67 (wire F711-GN) of the Machine ECM and the appropriate connector contacts (wire F711-GN) of the other ECMs.

   • Measure the resistance between connector contact J2-68 or J2-70 (wire F712-GY) of the machine ECM and the appropriate connector contacts (wire F712-GY) of the other ECMs.

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 or replace the machine harness.

  STOP

Test Step 5. CHECK FOR ADDITIONAL DIAGNOSTIC CODES FOR THE OTHER ECMS.

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

2. One at a time, reconnect all of the ECMs that use the CAN A data link.

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

4. After each of the ECMs has been reconnected, check for diagnostic codes that are logged against that ECM

Expected Result:

Diagnostic codes are not present for the other ECMs.

Results:

• OK - Diagnostic codes are not present for the other ECMs. The machine ECM may have failed.

  Repair: ECM has failure is unlikely. Perform this procedure again. If the problem is not found, ECM replacement may be necessary. Prior to replacing an ECM, always contact your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. See the Troubleshooting, "Electronic Control Module (ECM) - Replace"

  STOP

• NOT OK - Diagnostic codes are present for another ECM.

  Repair: Perform the procedure for the active diagnostic code.

  STOP