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 | ||
|---|---|---|
| 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.
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| Illustration 1 | g01392838 |
Typical schematic for the Cat Data Link | |
Test Step 1. Inspect the Electrical Connectors and the Wiring
- Remove electrical power from the ECM.
- Thoroughly inspect connector (1) and connector (2). Refer to Troubleshooting, "Electrical Connectors - Inspect".
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| Illustration 2 | g01139425 |
ECM (1) J1/P1 connectors (2) J2/P2 connectors | |
- Perform a 45 N (10 lb) pull test on each of the wires that are associated with the Cat Data Link.
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| Illustration 3 | g01394774 |
P1 terminals that are associated with the Cat Data Link (P1-3) Cat Data Link − (P1-9) Cat Data Link + | |
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| 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 − | |
- 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.
STOP
Test 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.
Show/hide table
Table 2 Resistance Measurements for the Cat Data Link Connector and Terminal Terminal P1-9 (Cat Data Link +) All of the other terminals on the P1 connector Ground stud P1-3 (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 - Each check of the resistance indicates an open circuit. Proceed to Test Step 3.
- Not OK - At least one check of the resistance does not indicate an open circuit. There is a short circuit in the harness or in a connector.
Repair: Repair the connectors and/or the wiring. Replace parts, if necessary. Verify that the original problem is resolved.
STOP
Test Step 3. Check for an Open Circuit
- Disconnect the service tool connector.
- Fabricate a jumper wire. Use the jumper wire in order to create a short circuit between terminals D (Cat Data Link +) and terminal E (Cat Data Link −) on the service tool connector.
- Measure the resistance between P1-9 (Cat Data Link +) and P1-3 (Cat Data Link −).
- Measure the resistance between the terminals at the connector for each control module that was connected to the Cat Data Link. Refer to Illustration 1.
- Remove the jumper wire from the service tool connector.
Expected Result:
Each check of the resistance indicates a short circuit.
Results:
- OK - Each check of the resistance indicates a short circuit.
Repair: Perform the following procedure:
- Connect the J1/P1 connectors. Connect Cat ET to the service tool connector.
- Check the Cat Data Link for proper operation. If the data link does not operate correctly, there may be a problem with the ECM.
Temporarily install a new ECM. Check the Cat Data Link again. If the new ECM solves the problem, install the original ECM and verify that the original problem returns. If the new ECM operates correctly and the original ECM does not operate correctly, replace the original ECM. Refer to Troubleshooting, "ECM - Replace".
STOP
- Not OK - At least one check of the resistance does not indicate a short circuit. There is an open circuit or excessive resistance in the harness. There may be a problem with a connector.
Repair: Repair the wiring and/or the connectors. Replace parts, if necessary. Verify that the original problem is resolved.
STOP