PLATE 0019493 - Caterpillar

Illustration 1 g03398178
Connections of the CAN A (SAE J1939) Data LinkNote: The above illustration is a simplified schematic. Refer to the complete machine electrical schematic for all of the harness connections for the CAN A data link circuit. This diagnostic code is recorded when the machine ECM stops receiving expectant information on the CAN A data link. Test Step 1. INSPECT THE CAN A DATA LINK HARNESS CONNECTIONS
Turn the disconnect switch to the OFF position.
Inspect all harness connections that are related to the CAN A Data Link. Make sure that the connectors are clean and tight. Refer to Troubleshooting , "Electrical Connector - Inspect" in this manual.
Check the connectors for proper mating. Ensure that all the seals are present and in place.
Check the harness for signs of damage or abrasion.
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.
Check the exposed wires at the connectors for nicks or signs of abrasion.
Check for moisture inside the connector.
Check the connectors for dirty contacts or corroded contacts.
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. STOPTest Step 2. CHECK THE RESISTANCE OF THE CAN A DATA LINK CIRCUITNote: Two 120 ohm data link terminating resistors are connected in parallel in the data link circuit. When the resistance of the circuit is measured, the circuit should measure approximately 60 ohms. Ensure that the data link circuits are intact with all harness connections connected.
Disconnect switch remains in the OFF position. The resistance measurement in the next step will not be correct if the disconnect switch is in the ON position. Note: If the machine ECM J2 connector has been disconnected, place a jumper between J2-67 and J2-56 and another jumper between J2-68 and J2-70 to complete the CAN A data link circuit.
At the Machine ECM, measure the resistance between contact J2-67 or J2-56 (wire F711-GN) and contact J2-68 or J2-70 (wire F712-GY). Also at the service connector, measure the resistance between Pin F (wire F711-GN) and Pin J (wire F712-GY) Expected Result:Resistance measurements of the CAN A data link circuit are approximately 60 ohms. Results:
OK - The resistance measurement is approximately 60 ohms. The resistance measurement is indicating that the resistors are connected and are not faulty. There is not an open