PLATE 5M8834 - Caterpillar

The CAN data link is used to communicate information between the Electronic Control Module (ECM) and other modules. Use this procedure to troubleshoot any suspect problems with the CAN data link.This procedure covers the 247-09 J1939 Data Link communications.This procedure identifies the following problems:
Faulty connectors
Missing termination resistors
Short circuits
Open circuits
Faulty J1939 display
Illustration 1 g01119843
Schematic for the CAN data link
Illustration 2 g01167488
Engine view (typical example)
(1) J1/P1 ECM connectors
Illustration 3 g01149983
Engine view (typical example)
(2) J61 customer connector
(3) J63 service tool connector
Illustration 4 g01215698
P1 terminals that are associated with the CAN data link
(P1-34) CAN data link −
(P1-42) CAN shield
(P1-50) CAN data link +
Illustration 5 g01123351
J61/P61 terminals that are associated with the CAN data link
(16) CAN shield
(17) CAN data link +
(18) CAN data link −
Table 1
Troubleshooting Test Steps Values Results
1. Inspect the Electrical Connectors and the Wiring
A. Turn the keyswitch to the OFF position.
B. Thoroughly inspect connectors (1), (2), and (3). Thoroughly inspect the connectors for each module that is connected to the CAN data link. Refer to Troubleshooting, "Electrical Connectors - Inspect".
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 allen head screw on each ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque value.
E. Check the allen head screw on the customer connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque value.
F. Check the wiring harnesses for abrasion, for corrosion and for pinch points.
Connectors and Wiring
Results: The harness and the wiring appear to be OK. Proceed to Test Step 2.
Results: There is a problem in the wiring harness.
Repair: Repair the connectors and/or the wiring. Replace parts, if necessary. Ensure that all of the seals are properly in place and ensure that the connectors are coupled. Verify that the problem is resolved.
STOP
2. Check for Codes
A. Connect Cat® Electronic Technician to the service tool connector.
B. Turn the keyswitch to the ON position.
C. Observe the active diagnostic code screen on Cat ET. Wait at least 15 seconds so that any diagnostic codes may become active. Check for a 247-09 diagnostic code.
Codes
Results: No codes are active.
Repair: The problem may be intermittent. If the problem is intermittent, refer to Troubleshooting, "Electrical Connectors - Inspect".
STOP
Results: A 247-09 diagnostic code is active. Proceed to Test Step 3.
3. Verify the Proper Installation of the CAN Data Link
A. Disconnect the J1939 display.
B. Disconnect the P1 connector and measure the resistance between terminals P1-50 (CAN data link +) and P1-34 (CAN data link -).
CAN Data Link
Results: The resistance is between 57 and 63 Ohms. Proceed to Test Step 6.
Results: The resistance is between 114 Ohms and 126 Ohms. A terminating resistor is missing.
Repair: Verify that two terminating resistors exist on the data link. One resistor must be located on each end of the data link. If the optional harness is ordered with the engine, the engine is shipped with one terminating resistor that is installed between the ECM and the customer connector. Refer to the appropriate