GASKET 8M0904 - Caterpillar

System Operation Description: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 g01175308
Schematic for the CAN data link
Test Step 1. Inspect the Electrical Connectors and the Wiring
Turn the keyswitch to the OFF position.
Illustration 2 g01146374
Engine view (typical example)
(1) J1/P1 ECM conntctors
Illustration 3 g01149983
Engine view (typical example)
(2) J61 customer connector
(3) J63 service tool connector
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".
Illustration 4 g01102141
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 −
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the CAN data link.
Check the allen head screw on each ECM connector for the proper torque. Also, check the allen head screw on the customer connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the wiring harnesses for abrasion, for corrosion and for pinch points. Expected Result:All connectors, pins and sockets are completely coupled and/or inserted. The harness and wiring are free of corrosion, of abrasion and of pinch points.Results:
OK - The harness and the wiring appear to be OK. Proceed to Test Step 2.
Not OK - 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 completely coupled. Verify that the problem is resolved.STOPTest Step 2. Check for Active Diagnostic Codes
Connect the Caterpillar Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools".
Turn the keyswitch to the ON position.
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. Expected Result:No diagnostic codes are active.Results:
OK - No codes are active.Repair: The problem may be intermittent. If the problem is intermittent, refer to Troubleshooting, "Electrical Connectors - Inspect".STOP
Not OK - A 247-09 diagnostic code is active. Proceed to Test Step 3.Test Step 3. Verify the Proper Installation of the CAN Data Link
Disconnect the J1939 display.
Disconnect the P1 connector and measure the resistance between terminals P1-50 (CAN data link +) and P1-34 (CAN data link -). Expected Result:The resistance is between 57 and 63 Ohms.Results:
OK - The resistance is between 57 and 63 Ohms. Proceed to Test Step 6.
Not OK - 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