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.
| Diagnostic Codes Table | ||
|---|---|---|
| Description | Conditions which Generate this Code | System Response |
| 248-9 @CatDatalinkLong@ 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 communication between electronic modules. The data link is used to communicate information from the engine's ECM to Caterpillar Electronic Technician (ET). The data link is used for programming and for troubleshooting the ECM.
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. This information will not be available if communication fails between the ECM and Cat ET.
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| Illustration 1 | g01258113 |
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Typical example | |
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| Illustration 2 | g01444508 |
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Location of the ECM connectors (1) J2/P2 ECM connectors (2) J1/P1 ECM connectors | |
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| Illustration 3 | g01241456 |
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P1 ECM connector (P1-8) Cat Data Link + (P1-9) Cat Data Link − | |
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| Illustration 4 | g01258218 |
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Connector "A" (Terminal 5) Cat Data Link − (Terminal 6) Cat Data Link + | |
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| Illustration 5 | g01241460 |
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Service tool connector (Terminal D) Cat Data Link + (Terminal E) Cat Data Link − | |
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| Illustration 6 | g01258219 |
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Connector "G" (Terminal 27) Cat Data Link + (Terminal 14) 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 coupled and/or inserted, and the harness and wiring are free of corrosion, of abrasion, and of pinch points.
Results:
- OK - The connectors and wiring are OK. Proceed to Test Step 2.
- Not OK - The connectors and/or wiring need repair.
Repair: Repair the connectors and/or wiring or replace the connectors and/or wiring.
STOP
Test Step 2. Check for Shorts in the Harness
- Disconnect ECM connector J1/P1 at the engine ECM.
- Disconnect any control modules from the Cat Data Link.
- Disconnect Cat ET from the service tool connector.
- Measure the resistance from P1-8 to every terminal on ECM connectors P1 and P2.
- Measure the resistance from P1-8 to the chassis ground.
- Measure the resistance from P1-9 to every terminal on ECM connectors P1 and P2.
- Measure the resistance from P1-9 to the chassis ground.
Expected Result:
The resistance measurement indicates an open circuit.
Results:
- OK - The resistance measurement indicates an open circuit. Proceed to Test Step 3.
- Not OK - The resistance measurement indicates a short circuit. There is a short in the harness or in the connectors.
Repair: Repair the connectors and/or wiring or replace the connectors and/or wiring.
STOP
Test Step 3. Check for an Open in the Harness
- Use a suitable piece of wire to create a short circuit at the service tool connector. Short terminal D and terminal E together.
- Measure the resistance between P1-8 and P1-9.
- Measure the resistance at the connectors of any other control modules.
Expected Result:
The resistance measurement indicates a short circuit.
Results:
- OK - The resistance measurements indicate a short circuit. The Cat Data Link is OK.
Repair: There could be a problem with a module or with the ECM. If the problem is intermittent, perform the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
STOP
- Not OK - The resistance measurements do not indicate a short circuit. There is an open circuit in the harness or connectors.
Repair: Repair the connectors or wiring and/or replace the connectors or wiring.
STOP