Troubleshooting

Circuit Tests
i06008869
Data Link - Test
Use this procedure if a fault is suspected in the CAN
data link. This procedure also covers the following
diagnostic codes:
Table 62
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.
639-14 J1939 Network #1 : Special Instruction Another controller has incorrectly stopped transmitting a signal on 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 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.
124 UENR0612-07
Circuit Tests
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