PUMP-HYD 20R2009 - Caterpillar

Table 1
Diagnostic Trouble Codes for the CAN Data Link
J1939 Code Description Notes
639-9 J1939 Network #1 : Abnormal Update Rate Another controller has incorrectly stopped transmitting a J1939 speed request (TSC1) or another controller has incorrectly started transmitting a J1939 speed request.
The ECM will log the diagnostic code.
The engine will not start.
1235-9 J1939 Network #3 : Abnormal Update Rate Communication has been lost to one or more of the devices on the datalink. If multiple devices are not communicating, there is likely a problem with the data link wiring, power, or ground circuits.
1235-14 J1939 Network #3 : Special Instruction The affected ECM is missing expected parameters. The following background information is related to this procedure:The CAN data link is also known as J1939 data link. The data link is an industry standard for sending data between different devices in the same application.High-speed data is transferred via the data link. The data link cannot be accurately tested without complicated equipment. The data link requires a resistance of 60 Ohms between the two wires in order to transmit the data correctly. This resistance is made up of two 120 Ohm resistors. The two resistors are known as "Terminating Resistors". The terminating resistors should be at opposite ends of a data link circuit. If this resistance is not present, then the data will be intermittent or unreadable.Note: The wiring for the J1939 data link is a shielded twisted-pair cable. If the wiring is damaged, the replacement type must be shielded twisted-pair cable.
Illustration 1 g06254311
Typical example of the schematic for the CAN data link
(1) 70 Way Connector
Illustration 2 g06081623
70 Way Connector
Table 2
Troubleshooting Test Steps Values Results
1. Inspect Electrical Connectors and Wiring
A. Turn the keyswitch to the OFF position.
B. Inspect the connectors in the circuit for the CAN data link.
Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
C. Perform a 30 N (6.7 lb) pull test on each of the wires that are associated with the CAN data link.
D. Check all of the wiring associated with the CAN data link for abrasions and pinch points.
Damaged wire or connector Result: A damaged wire or damaged connector was found.
Repair the damaged wire or the damaged connector.
Use the electronic service tool to clear all logged diagnostic codes. Verify that the repair eliminates the fault.
Result: A damaged wire or damaged connector was not found.
Proceed to Test Step 2.
2. Check the Data Link Terminating Resistance
A. Disconnect the P1 connector from the ECM.
B. Measure the resistance between the J2: 23 and J2 31.
Between 50 Ohms and 70 Ohms
Result: The resistance is less than 50 Ohms - there is a short circuit in the harness.
Repair the connectors or the harness and/or replace the connectors or the harness. Ensure that all of the seals are correctly in place and ensure that the connectors are correctly connected.
Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.
Result: The resistance is between 110 and 130 Ohms - one of the terminating resistors may have failed.
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