Note: This procedure checks for an open circuit or a short circuit in the Cat Data Link. If you are experiencing problems with communications between the Caterpillar Electronic Technician (ET) and the Electronic Control Module (ECM), refer to Troubleshooting, "Electronic Service Tool Will Not Communicate with ECM" 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. This information will not be available if communication fails between the ECM and Cat ET.
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| Illustration 1 | g01129351 |
Schematic for the marine auxiliary | |
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| Illustration 2 | g01158305 |
Schematic for the marine generator set | |
Test Step 1. Inspect the Electrical Connectors and the Wiring
- Turn the keyswitch to the OFF position.
- Thoroughly inspect connectors (1), (2) and (3). Inspect all of the other connectors that are associated with the circuit for the Cat Data Link.
Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
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| Illustration 3 | g01130303 |
Typical engine components for the Cat Data Link (1) J61 customer connector (2) J60 connector for the electronic service tool (3) J1/P1 connectors | |
- Verify that the wiring for the Cat Data Link is installed correctly. Refer to Special Instruction, REHS1187, "Electronic Installation Guide" for additional information.
- Check the following components for abrasion, for corrosion, or for incorrect attachment.
- Global Positioning System Interface Module (GPSIM)
- Engine Vision Interface Module (EVIM)
- Engine Vision Display
- EMCP 3 (GSC)
Ensure that the 163-3973 Cable is securely connected to the EVIM and to the Engine Vision Display.
- Global Positioning System Interface Module (GPSIM)
- Verify that each individual ECM is programmed to the proper engine location.
- 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 4 | g01157723 |
P1 terminals that are associated with the Cat Data Link (P1-8) Cat Data Link + (P1-9) Cat Data Link − | |
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| Illustration 5 | g01130718 |
Terminals on the customer connectors that are associated with the Cat Data Link (6) Cat Data Link − (7) Cat Data Link + | |
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| Illustration 6 | g01130713 |
Terminals on the service tool connectors that are associated with the Cat Data Link (D) Cat Data Link + (E) Cat Data Link − | |
- 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 allen head screw on the customer connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
- 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 wiring appear to be okay. Proceed to Test Step 2.
- Not OK - There is a problem in the connectors and/or the wiring.
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 the Wiring at each Module
- Turn the keyswitch to the ON position.
- Measure the supply voltage between terminals B+ and B− at each interface module in order to verify that the modules are receiving the correct operating voltage.
- Verify that each wire of the Cat Data Link is connected to the correct terminal on each interface module.
Expected Result:
The voltage measurement at each interface module is between 11.0 VDC and 13.5 VDC for a 12 volt system and between 22.0 VDC and 27.0 VDC for a 24 volt system. The wires for the Cat Data Link are connected correctly.
Results:
- OK - The wiring at each module is installed correctly. Proceed to Test Step 3.
- Not OK - The wiring at a module is not installed correctly.
Repair: Make the necessary repairs. Verify that the repair eliminates the problem.
STOP
Test Step 3. Check for a Short Circuit
- Turn the keyswitch to the OFF position.
- Disconnect the wiring for the Cat Data Link from the EVIM the GSC,and the GPSIM.
- Disconnect the P1 and P2 connectors from the ECM.
- Measure the resistance between the points that are listed in Table 1. Be sure to wiggle the wires in the harnesses as you make each resistance measurement.
Show/hide table
Table 1 Resistance Measurements for the Wiring Harness Connector and Terminal Terminal P1-8 (Cat Data Link +) All of the other terminals on the P1 connector All of the terminals on the P2 connector Engine ground P1-9 (Cat Data Link −) All of the other terminals on the P1 connector All of the terminals on the P2 connector Engine ground
Expected Result:
All of the resistance measurements indicate an open circuit.
Results:
- OK - All of the resistance measurements indicate an open circuit. Proceed to Test Step 4.
- Not OK - At least one resistance measurement does not indicate an open circuit. There is a problem with a wiring 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 4. Check for an Open Circuit
- Turn the keyswitch to the OFF position.
- Disconnect the P1 ECM connector.
- Use a jumper wire to create a short circuit between terminals P1-8 and P1-9.
- Measure the resistance between the terminals for the Cat Data Link at the connector for each of the modules.
Note: Wiggle the harness during the following measurements in order to reveal any intermittent short condition.
Expected Result:
Each resistance measurement is less than ten Ohms.
Results:
- OK - Each resistance measurement is less than ten Ohms. There is not an open circuit. Connect the ECM connectors. Proceed to Test Step 5.
- Not OK - At least one resistance measurement is greater than ten Ohms. The wiring for the Cat Data Link has excessive resistance. There may be a problem in a connector.
Repair: Repair the wire and/or the connector, when possible. Replace parts, if necessary. Verify that the problem is resolved.
STOP
Test Step 5. Test the Module on a Different Engine
Test the suspect module on a different engine.
Expected Result:
The module does not operate correctly on a different engine.
Results:
- OK - The module does not operate correctly on a different engine.
Repair: Replace the module. Verify that the problem is resolved.
STOP
- Not OK - The module operates correctly on a different engine. There may be a problem with the ECM.
Repair: It is highly unlikely that the ECM has failed. Perform this entire procedure again. If the problem is still not resolved, replace the ECM. Refer to Troubleshooting, "Replacing the ECM". Verify that the problem is resolved.
STOP