GEAR ASSEM. (12 teeth) 3P7619 - Caterpillar

System Operation Description:Use this procedure if a fault is suspected in the CAN data link.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 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 g02453557
Typical example of the schematic for the CAN A data link
Illustration 2 g02730831
Typical example of the schematic for the CAN B data link
Illustration 3 g01959420
Typical example of the schematic for the CAN C data link
Illustration 4 g02453576
Typical view of the pin locations on the P1 connector (34) CAN A- (50) CAN A+ (37) CAN C+ (38) CAN C-
Illustration 5 g01980934
Typical view of the pin locations on the P2 connector (21) CAN B- (29) CAN B+ (30) CAN A+ (31) CAN A-Test Step 1. Inspect Electrical Connectors and Wiring.
Turn the keyswitch to the OFF position.
Thoroughly inspect the connectors in the circuit for the CAN data link.Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the CAN data link. Refer to Illustration 2.
Check the harness for abrasion and pinch points from the keyswitch to the Electronic Control Module (ECM).Expected Result:All connectors, pins, and sockets are correctly connected. The harness should be free of corrosion, abrasion and/or pinch points.Results:
OK - Proceed to Test Step 2.
Not OK - Repair: Perform the following repair:Repair the connectors and/or the wiring, or