SEAL 3H1397 - Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with the Cat Data Link. Also, use this procedure if the diagnostic code in Table 1 is active or easily repeated.
Table 1
Diagnostic Codes Table
J1939 Code and Description Conditions which Generate this Code System Response
248-9 Cat Data Link not communicating The Electronic Control Module (ECM) detects a loss of communication over the data link for two or more seconds. The code is logged. The Cat Data Link is used for the communication between the electronic modules. The Cat Data Link is used to communicate information from the ECM to the Electronic Monitoring System (EMS). The Cat Data Link is used for programming and troubleshooting the ECM.The ECM communicates with the EMS in order to share engine information and diagnostics that may affect engine operation.The ECM communicates with the Caterpillar Electronic Technician (ET) in order to share status and diagnostic information. The Cat ET can also be used to configure the ECM parameters on the engine. This information will not be available if communications fail between the ECM and the Cat ET.
Illustration 1 g03318854
Typical schematic
Illustration 2 g03323097
Terminal locations of the Cat data link at the J1-P1 connector
(P1-8) Cat data link +
(P1-9) Cat data link -
Illustration 3 g03323101
Terminal locations at the service tool connector
(Terminal D) Cat data link +
(Terminal E) Cat data link -
Illustration 4 g03323098
Terminal locations at the customer connector
(Terminal 13) Cat data link +
(Terminal 14) Cat data link -
Table 2
Troubleshooting Test Step Value Result
1.Active Codes and Logged Codes
A. Establish communication between Cat Electronic Technician (ET) and the engine ECM. Refer to Troubleshooting, "Electronic Service Tools", if necessary.
B. Determine if the 248-9 code is active or logged.
Codes
Result: A Diagnostic code is present.
Repair: Troubleshoot any codes before proceeding with this procedure. Verify that the repair eliminated the problem.
Result: A diagnostic code is not present.
Proceed to Test Step 2.
2. Inspect the Electrical Connectors and the Wiring
A. Turn the main disconnect switch to the OFF position.
B. Thoroughly inspect the ECM connectors. Inspect all other connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect"
C. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit.
D. Check the ECM connector (allen head screw) for the proper torque of 6.0 N m (55 lb in).
E. Check the customer connector (allen head screw) for the proper torque of 2.25 0.25 N m (20 2 lb in).
F. Check the harness and the wiring for abrasion and for pinch points.
Connectors
Result: The connectors and wiring appear to be OK.
Proceed to Test Step 3.
Result: The connectors and/or wiring are not OK.
Repair: Repair the wiring and/or connectors. Replace parts, if necessary. Ensure that all of the seals are properly in place and ensure that the connectors are coupled.
Verify that the repair eliminated the problem.
STOP
3. Check for Shorts in the Harness
A. Disconnect the P1 ECM connector.
B. Disconnect any module that is connected to the Cat Data Link.
C. Measure the continuity between the P1-9 and every terminal on the ECM connectors P1