MANIFOLD-EXHAUST 9L5521 - Caterpillar

System Operation Description:Use this procedure to troubleshoot the electrical system if a problem is suspected with the Cat Data Link or if the diagnostic code in Table 1 is active or easily repeated.
Table 1
Diagnostic Codes Table
Code and Description Conditions which Generate this Code System Response
248-9 @CatDatalinkLong@ not communicating Communication on the Cat Data Link was lost for the last two seconds. The ECM will log the diagnostic code. The Cat Data Link is used for communication between electronic modules. The Cat Data Link is used to communicate information from the engine's Electronic Control Module (ECM) to other electronic systems. The Cat Data Link is used for programming and for troubleshooting the ECM.The engine's ECM communicates with Caterpillar Electronic Technician (ET) in order to share information on engine status and on engine diagnostics. Cat ET can also be used to configure the engine's parameters. This information will not be available if communication fails between the engine's ECM and Cat ET.
Illustration 1 g01321352
Typical example
Illustration 2 g01156133
P1 ECM connector
(P1-8) Cat Data Link +
(P1-9) Cat Data Link −
Illustration 3 g01161996
Customer connector
(Terminal g) Cat Data Link +
(Terminal h) Cat Data Link −
Illustration 4 g01161999
Service tool connector
(Terminal D) Cat Data Link +
(Terminal E) Cat Data Link − Test Step 1. Inspect Electrical Connectors and Wiring
Remove power from the ECM.
Thoroughly inspect the J1/P1 ECM connector and the J2/P2 ECM connector. Inspect all of the connectors that are associated with the circuit. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connectors that are associated with the circuit.
Check the allen head screw on each ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and wiring for abrasion and for pinch points. Expected Result:All connectors, pins, and sockets are completely inserted and coupled. The harness and wiring are free of corrosion, of abrasion, and of pinch points.Results:
OK - The harness and the connectors appear to be OK. Proceed to Test Step 2.
Not OK - The connectors and/or the wiring are not OK.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 original problem is resolved.STOPTest Step 2. Check for a Short Circuit
Disconnect the P1 ECM connector.
Disconnect Cat ET from the service tool connector.
Disconnect any other control modules from the Cat Data Link. Refer to the electrical schematic in order to identify other control modules on the Cat Data Link.
Measure the resistance between the points that are listed in Table 2. Be sure to wiggle the wires in the harnesses as you make each resistance measurement.
Table 2
Resistance Measurements for the Cat Data Link
Connector and Terminal Terminal
P1-8 (Cat Data Link +) All of the other terminals on the P1 connector
Ground stud
P1-9 (Cat Data Link -) All of the other terminals on the P1 connector
Ground stud Expected Result:Each check of the resistance indicates an open circuit.Results:
OK