The CAN data link is used to communicate information between the Electronic Control Module (ECM) and other modules. Use this procedure to troubleshoot any suspect problems with the CAN data link.
This procedure will identify the following problems:
- Faulty connectors
- Missing termination resistors
- Short circuits
- Open circuits
- Faulty J1939 display
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| Illustration 1 | g01136552 |
Schematic for the CAN 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 the J60 service tool connector.
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| Illustration 2 | g01136276 |
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 CAN data link.
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| Illustration 3 | g01136554 |
P1/J1 ECM connector (P1-10) J1939 Data + (P1-15) J1939 Shield (P1-16) J1939 Data - | |
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| Illustration 4 | g01136555 |
P3/J3 Customer connector (P3-16) J1939 Shield (P3-17) J1939 Data + (P3-18) J1939 Data - | |
- 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. Verify the Proper Installation of the CAN Data Link
- Disconnect the J1939 display.
- Disconnect the P1 ECM connector and measure the resistance between terminals P1-10 (CAN data link +) and P1-16 (CAN data link -).
Expected Result:
The resistance is between 57 and 63 Ohms.
Results:
- OK - The terminating resistors are correctly installed. Proceed to Test Step 3.
- Not OK - The resistance is between 114 Ohms and 126 Ohms. A terminating resistor is missing.
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.Refer to Illustration 1 in order to locate the correct placement of the terminating resistors. Install the missing terminating resistor. Verify that the problem is resolved.
STOP
- Not OK - The resistance is less than 57 Ohms. Proceed to Test Step 3.
- Not OK - The resistance is greater than 126 Ohms. Proceed to Test Step 4.
Test Step 3. Check for a Short Circuit
- Disconnect the J1/P1 ECM connector.
- Remove the terminating resistors from the CAN data link.
- If a J1939 display is installed, disconnect the display.
- 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 CAN Data Link Connector and Terminal Terminal P1-10 CAN data link + All of the other terminals on the P1 ECM connector
Engine groundP1-16 CAN data link -
Expected Result:
Each check of the resistance indicates an open circuit.
Results:
- OK - The harness is not shorted. Proceed to Test Step 4.
- 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 part, if necessary. Verify that the problem is resolved.
STOP
Test Step 4. 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 G and terminal F on the J60 service tool connector.
- Measure the resistance between P1-10 CAN data link + and P1-16 CAN 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 5.
- 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 5. Check the J1939 Display
- Connect the J1939 display to another engine.
- Operate the engine and monitor the J1939 display.
Expected Result:
The J1939 display operates properly.
Results:
- OK - The J1939 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 J1939 display does not operate properly on another engine.
Repair: Replace the J1939 display. Verify that the problem is resolved.
STOP