BASE 4361094 - Caterpillar

Table 1
Diagnostic Codes Table    
Code and Description    Conditions which Generate this Code    System Response    
248-9 @CatDatalinkLong@ not communicating     The battery voltage to the Electronic Control Module (ECM) has been above 9 VDC for the last two seconds.
The battery voltage to the ECM has been above 9 VDC for the last two seconds.
Communication was lost.     The ECM will log the diagnostic code.
All features that depend on the Cat Data Link will be disabled.    Note: This procedure checks for an open circuit or for a short circuit in the Cat Data Link. If you are experiencing problems with communications between Caterpillar Electronic Technician (ET) and the ECM, refer to Troubleshooting, "Electronic Service Tool Does Not Communicate" before you use this procedure.The Cat Data Link is the standard data link that is used by the ECM to communicate with Cat ET. The ECM communicates with Cat ET in order to share status information and diagnostic information. Cat ET can also be used to configure the ECM parameters.
Illustration 1 g01782013
Typical schematic for the Cat Data LinkTest Step 1. Inspect the Electrical Connectors and the Wiring
Remove electrical power from the ECM.
Illustration 2 g01139425
ECM (1) J1/P1 connectors (2) J2/P2 connectors
Thoroughly inspect connector (1) and connector (2). Refer to Troubleshooting, "Electrical Connectors - Inspect".
Illustration 3 g01394774
P1 terminals that are associated with the Cat Data Link (P1-3) Cat Data Link − (P1-9) Cat Data Link +
Illustration 4 g01365685
Terminal locations at the service tool connector that are associated with the Cat Data Link (Terminal D) Cat Data Link + (Terminal E) Cat Data Link −
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the Cat 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.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 that are 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    
P1-9 (Cat Data Link +)     All of the other terminals