The Cat Data Link is a two wire electrical connection that is used for communication between the Electronic Control Module (ECM), the displays for the Engine Monitoring System (EMS), and the Caterpillar Electronic Technician (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. This information will not be available if communication fails between the ECM and Cat ET. ECM serial numbers that have a suffix of "KS" will also flash program on the Cat Data Link.
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| Illustration 1 | g01136604 |
Schematic for the Cat Data Link | |
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The connection of any electrical equipment and the disconnection of any electrical equipment may cause an explosion hazard which may result in injury or death. Do not connect any electrical equipment or disconnect any electrical equipment in an explosive atmosphere. |
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Test Step 1. Inspect the Electrical Connectors and the Wiring
- Turn the keyswitch to the OFF position.
- Thoroughly inspect connectors (1) and (2). Also inspect all harnesses and connectors that are associated with the Cat Data Link.
Note: Refer to the Electrical System Schematic for information that is related to the application's wiring.
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| Illustration 2 | g01136614 |
Top view (1) J1/P1 ECM connector (2) J3/P3 Customer connector | |
- Perform a 45 N (10 lb) pull test on each of the wires that are associated with the Cat Data Link.
Note: Refer to the Electrical System Schematic for further information about the machine wiring.
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| Illustration 3 | g01136606 |
P1 ECM connector (P1-3) Cat Data Link + (P1-9) Cat Data Link - | |
- Check the allen head screw on the ECM connectors and the customer connector. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque value.
- Check the wiring harnesses for abrasion, for corrosion, and for pinch points.
Expected Result:
All connectors, pins and sockets are completely coupled and/or inserted. The harness and wiring are free of corrosion, of abrasion, and of pinch points.
Results:
- OK - The harness and the wiring appear to be OK. Proceed to Test Step 2.
- Not OK - There is a problem in the wiring harness.
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 problem is resolved.
STOP
Test Step 2. Check for a Short Circuit
- Disconnect the J1/P1 ECM connector.
- Disconnect all display modules from the Cat Data Link.
- Measure the resistance between P1-3 Cat Data Link − and P1-9 Cat Data Link +.
- Measure the resistance between P1-9 Cat Data Link + and the engine ground stud.
- Measure the resistance between P1-3 Cat Data Link − and the engine ground stud.
Expected Result:
Each check of the resistance indicates an open circuit.
Results:
- OK - The harness is not shorted. 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 a harness. There may be a problem with a connector.
Repair: Repair the wiring and/or the connector. Replace parts, if necessary. Verify that the problem is resolved.
STOP
Test Step 3. Check for an Open Circuit
- Verify that all of the connections are disconnected.
- Fabricate a jumper wire. Use the jumper wire in order to create a short circuit between terminal D and terminal E on the J60 service tool connector.
- Measure the resistance between P1-3 Cat Data Link − and P1-9 Cat Data Link +.
- Remove the jumper wire from the service tool connector.
Expected Result:
The resistance is less than ten Ohms.
Results:
- OK - The resistance is less than ten Ohms. There is not an open circuit. Proceed to Test Step 4.
- Not OK - The resistance is more than ten Ohms. There is an open circuit or excessive resistance in the circuit. There may be a problem in a connector.
Repair: Repair the wiring and/or the connector. Replace parts, if necessary. Verify that the problem is resolved.
STOP
Test Step 4. Check the EMS Display
- Connect the EMS display to another engine.
- Operate the engine and monitor the display.
Expected Result:
The EMS display operates properly.
Results:
- OK - The EMS display operates properly on another engine.
Repair: Connect the display to the original engine. If the display operates correctly, there may be a problem with an electrical connector. Refer to Troubleshooting, "Electrical Connectors - Inspect".If the display does not operate correctly on the original engine, there may be a problem with the ECM.It is unlikely that the ECM has failed. Perform this entire procedure again. If the display does not operate correctly, replace the ECM. Refer to Troubleshooting, "Replacing the ECM".
STOP
- Not OK - The EMS display does not operate properly on another engine.
Repair: Replace the EMS display. Verify that the problem is resolved.
STOP