EDGE AS 3670035 - Caterpillar

Table 1
Diagnostic Trouble Codes for CAN Data Link    
CDL Code    Code Description    Comments    
246-9     Proprietary CAN Data Link abnormal update rate     The proprietary CAN data link cannot communicate correctly.    
247-9     SAE J1939 Data Link abnormal update rate     The CAN data link cannot communicate correctly.    
1603-9     Machine Control Module abnormal update rate     The machine control ECM cannot communicate correctly with the engine ECM over the CAN data link.    Note: Refer to Troubleshooting, "Sensors and Electrical Connectors"for the locations of the components listed in this procedure.The following background information is related to this procedure:The CAN data link is also known as the J1939 data links. A 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 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 a 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 g03547176
Schematic for the CAN data link
Illustration 2 g03503181
View of the pin locations for the CAN data link on the P1 connector (20) CAN data link positive (21) CAN data link negative
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
45 N (10 lb) pull test on each of the wires that are associated with the CAN data link.
D. Check the screw for the ECM connectors for correct torque of
5 N m (44 lb in).
E. 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 and the P2 connector from the ECM.
B. Measure the resistance between P1:20 and P1:21.
   
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