RENR5042-02 103 Troubleshooting Section Repair: Verify that two terminating resistors exist on the data link. One resistor must be located on each end of the data link. The engine is shipped with one terminating resistor that is installed between the ECM and the customer connector. Repair: Repair the wiring and/or the connector. Replace part, if necessary. Verify that the problem is resolved. STOP. Refer to the appropriate electrical schematic in order to determine the missing resistor. Replace the missing resistor. Verify that the problem is resolved. Test Step 5. Check for an Open Circuit A. Verify that all of the connections are disconnected. B. Fabricate a jumper wire.
Use the jumper wire in order to create a short circuit between terminals G and F on the service tool connector. STOP. Not OK The resistance is less than 57 Ohms. Proceed to Test Step 4. C. Measure the resistance between terminals P1-50 (CAN data link +) and P1-34 (CAN data link -). Not OK The resistance is greater than 126 Ohms. Proceed to Test Step 5. D. Remove the jumper wire from the service tool connector. Test Step 4. Check for a Short Circuit Expected Result: A. Disconnect the J1/P1 ECM connector. The resistance is less than ten Ohms. B. Remove the terminating resistors from the CAN data link. Results: C. If a J1939 display is installed, disconnect the display.
OK – The resistance is less than ten Ohms. There is not an open circuit. Proceed to Test Step 6. D. Measure the resistance between the points that are listed in Table 16. Be sure to wiggle the wires in the harnesses as you make each resistance measurement. 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 part, if necessary. Verify that the problem is resolved. Table 16 STOP. Test Step 6. Check the J1939 Display A. Connect the J1939 display to another engine. B. Operate the engine and monitor the J1939 display. Expected Result:
Expected Result: The J1939 display operates properly. Each check of the resistance indicates an open circuit. Results: OK The J1939 display operates properly on another engine. Results: OK Each check of the resistance indicates an open circuit. Proceed to Test Step 5. 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”. 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.
If the display does not operate correctly on the original engine, there may be a problem with the ECM. Resistance Measurements for the CAN Data Link Connector and Terminal Terminal P1-50 (CAN data link +) All of the other terminals on the P1 connector Engine ground P1-34 (CAN data link -) All of the other terminals on the P1 connector Engine ground