3512C Petroleum Engines with Dynamic Gas Blending Caterpillar

Data Link - Test

Usage:

Use this procedure to troubleshoot the data link if a problem is suspected with the data link. Or, use this procedure if one of following diagnostic codes is active or easily repeated.

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Table 1
Diagnostic Codes
J1939 Code and Description	Conditions which Generate this Code	System Response
639-9 J1939 Network #1 : Abnormal Update Rate	Communication issue on the Global data link between the generator and the ISM. One module is no longer broadcasting.	The code is logged.
1231-9 J1939 Network #2 : Abnormal Update Rate	Communication issue with the fuel valve and the ISM on the CAN data link.	The code is logged.
1231-14 J1939 Network #2 : Special Instruction	All communications on the data link have been lost.	All communications on the data link have been lost.
2241-9 Source Address 241 : Abnormal Update Rate	The engine ECM is not communicating with the ISM.	All communications on the data link have been lost.
2452-9 Generator Total Real Power : Abnormal Update Rate	Communication issue on the Global data link between the ECM and the EMCP. One module is no longer broadcasting.	The code is logged. Gas substitution shuts off.

Note: If the only active code is 2452-9, troubleshoot the customer supplied load feedback signal. Refer to Application & Installation Guide, LEBW0026 for additional information.

Use this procedure to troubleshoot the electrical system if a problem is suspected with the CAN data link or the Cat Data Link.

Note: This procedure checks for an open or for a short in the data link circuits.

If Caterpillar Electronic Technician (ET) will not communicate with the ECM, refer to Troubleshooting, "Electronic Service Tool Does Not Communicate" before you begin this procedure. The procedure will verify that electrical power is being supplied to the ECM and to the service tool connector.

The data links are used to communicate information between the engine ECM and other control modules that are a part of the application. Cat ET also communicates with the ECM via the data links.

The service tool connector contains connections for electrical power and for the data links.

When the keyswitch is in the OFF position, Cat ET may communicate with the ECM. However, the communications may be disrupted and the communications may require frequent reconnection. To avoid this problem, place the keyswitch in the ON position when Cat ET is being used.

Cat ET may display the following error message:

"The version of the ECM is not recognized and the integrity of the changed parameters and displayed data is not guaranteed."

This message indicates one of the following conditions:

The flash file in the ECM is newer than the version of Cat ET.
The latest version of Cat ET has not been installed.

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Illustration 1	g03383096

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Illustration 2	g01444702
Terminal locations at the service tool connector (A) +Battery (B) −Battery (C) CAN data link global shield (D) Cat Data Link + (E) Cat Data Link − (F) CAN data link global − (G) CAN data link global +

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Illustration 3	g03383124
Terminal locations at the P1 ECM connector that are for the data links (P1-8) Cat Data Link + (P1-9) Cat Data Link − (P1-34) Global CAN data link − (P1-42) Global CAN shield (P1-50) Global CAN data link + (P1-52) +Battery (P1-53) +Battery (P1-55) +Battery (P1-57) +Battery (P1-61) −Battery (P1-63) −Battery (P1-65) −Battery (P1-67) −Battery (P1-69) −Battery (P1-70) Keyswitch

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Illustration 4	g01326307
Terminal locations at the P2 ECM connector that are for the data link (P2-11) Local CAN data link − (P2-12) Local CAN data link + (P2-23) Local CAN shield

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Illustration 5	g03325860
Terminal locations at the P1 ISM connector that are for the data link (P1-48) Global CAN data link − (P1-49) Global CAN shield (P1-50) Global CAN data link + (P1-51) Local CAN data link − (P1-52) Local CAN shield (P1-61) Local CAN data link + (P1-66) −Battery (P1-67) −Battery (P1-68) + Battery (P1-69) + Battery (P1-70) Keyswitch

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Illustration 6	g01355248
Terminal locations at the termination resistors (A) CAN data link + (B) CAN data link − (C) Shield

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Table 2
Troubleshooting Test Steps	Values	Results
1. Inspect the Electrical Connectors and the Wiring Note: Carefully follow this procedure to identify an intermittent problem. A. Perform a visual inspection of the wiring between the P1 and P2 ECM connectors, the termination resistors, and the service tool connector. Also, inspect the wiring and the connectors at various controllers and control boxes. Look for these problems: -Harness damage that is caused by chafing - Harness damage that is caused by excessive heat -Look for moisture on the wiring and in the connectors. - Pull on the wires that are associated with the data links. This test verifies that the wire is properly crimped to the terminal and that the terminal is properly inserted into the connector.	Connectors	Result: The wiring and the connectors appear to be OK. Proceed to Test Step 2. Result: There is a problem with the wiring or with a connector. Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all the connector seals are properly in place and ensure that the connectors are coupled. Verify that the repair eliminates the problem.
2. Bypass the Wiring for the Data Link A. Connect the 217-0113 Wiring Harness (ECM BYPASS) to the J1 connector, to the 332-7381 Data Link Cable As, and to the battery. B. Restore the electrical power to the ECM. C. Try to establish communication between Cat ET and the ECM.	Data link	Result: Cat ET and the ECM communicate. Repair: Cat ET and the ECM communicate when the bypass harness is installed. However, communication cannot be established via the engine wiring. Disconnect the electrical connector from each of the control modules that is on the data link one at a time. This test will isolate the problem. Try to establish communication between Cat ET and the ECM after disconnecting each module. The problem is in the control module if disconnecting the module allows Cat ET and the ECM to communicate. If a module is suspect, replace the module. Verify that the repair eliminates the problem. The control module is OK if the problem remains when the module is disconnected. Result: Cat ET and the ECM do not communicate. Repair: Communication between Cat ET and the ECM is not established when the bypass harness is installed. Temporarily connect a test ECM. Refer to Troubleshooting, "Test ECM Mode". Note: Before you consider replacing the ECM, consult with the Dealer Solutions Network (DSN) for assistance. Verify that the repair eliminates the problem.
3. Check the Wiring for the Data Links for a Short Circuit A. Turn the main disconnect switch to the OFF position. B. Disconnect the negative cable from the battery. C. Disconnect the P1 and P2 ECM connectors from the ECM. D. Measure the resistance between the following terminals at the ECM: -P1-8 (Cat Data Link +) and P1-61 (-Battery) -P1-9 (Cat Data Link -) and P1-61 (-Battery) -P1-34 (Global CAN data link -) and P1-61 (-Battery) -P1-50 (Global CAN data link +) and P1-61 (-Battery) -P2-11 (Local CAN data link -) and P1-61 (-Battery) -P2-12 (Local CAN data link +) and P1-61 (-Battery) E. Measure the resistance between the following terminals at the ISM: -P1-48 (Global CAN data link -) and P1-66 (-Battery) -P1-50 (Global CAN data link +) and P1-66 (-Battery) -P1-51 (Local CAN data link -) and P1-66 (-Battery) -P1-61 (Local CAN data link +) and P1-66 (-Battery)	Short Circuit	Result: Each measurement indicates an open circuit. The wiring for the data links does not have a short circuit. Proceed to Test Step 4. Result: At least one measurement does not indicate an open circuit. Repair: At least one measurement is less than 5 Ohms. The wiring for a data link has a short circuit. Determine the cause of the short circuit. Repair the problem, when possible. Replace parts, if necessary. Verify that the repair eliminates the problem.
4. Check the Wiring for the Data Links for an Open Circuit A. Connect a jumper wire between terminals P1-8 and P1-9 at the ECM. B. At the service tool connector and the connector for each control module, measure the resistance between the terminals for the Cat Data Link. C. Connect a jumper wire between terminals P1-34 and P1-50 D. At each service tool connector measure the resistance between the terminals for the CAN data link. Also, at the connector for each control module on the global network, measure the resistance between the terminals for the CAN data link. E. Connect a jumper wire between terminals P2-11 and P2-12 F. At each service tool connector measure the resistance between the terminals for the CAN data link. Also, at the connector for each control module on the global network, measure the resistance between the terminals for the CAN data link. G. Connect a jumper wire between terminals P1-51 and P1-61 at the ISM. H. At each service tool connector measure the resistance between the terminals for the CAN data link. Also, at the connector for each control module on the global network, measure the resistance between the terminals for the CAN data link. I. Connect a jumper wire between terminals P1-48 and P1-50 at the ISM. J. At each service tool connector measure the resistance between the terminals for the CAN data link. Also, at the connector for each control module on the global network, measure the resistance between the terminals for the CAN data link.	Open circuit	Result: All the resistance measurements indicate a short circuit. Repair: If you are troubleshooting the Cat Data Link, the data link appears to be OK. The problem is probably an intermittent problem in a connector or in the harness. If the problem persists, perform this test procedure again. If an intermittent problem is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect" for information that is related to troubleshooting intermittent electrical problems. If you are troubleshooting the CAN data link, remove the jumper wires. Leave the control modules disconnected from the data link Proceed to Test Step 5. Result: At least one of the resistance measurements indicates an open circuit. Repair: Determine the cause of the open circuit. Repair the problem, when possible. Replace parts, if necessary. Verify that the repair eliminates the problem.

5. Check the Termination Resistors for the J1939 Data Link Perform this test step only if you are troubleshooting a problem with the CAN data link. A. Ensure that all the control modules are disconnected from the data link. At the service tool connector, measure the resistance between the terminals for the CAN data link.	45 Ohms and 75 Ohms	Result: The resistance is between 45 Ohms and 75 Ohms. Repair: The termination resistors are OK. The data link appears to be OK. The problem is probably an intermittent problem in a connector or in the harness. If the problem persists, perform this test procedure again. If an intermittent problem is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect" for information that is related to troubleshooting intermittent electrical problems Result: The resistance is approximately 120 Ohms. There is a problem with a termination resistor. Repair: Determine the cause of the missing termination resistor. Repair the problem, when possible. Replace parts, if necessary. Verify that the problem is resolved. Result: The resistance is greater than 140 ohms. There is a problem with both termination resistors. Repair: Determine the cause of the problem. Repair the problem, when possible. Replace parts, if necessary. Verify that the repair eliminates the problem.

If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).