14430 3 Mercury BASE

Illustration 1 g01269477
Typical schematic for the CAN data link
Test Step 1. Inspect the Electrical Connectors and the Wiring
Remove the electrical power from the ECM.
Illustration 2 g01121169
Typical engine components for the CAN data link
(1) Connector for the electronic service tool
(2) Customer connector
(3) J1/P1 connectors
Thoroughly inspect connectors (1), (2), and (3). Thoroughly inspect the connectors for each module that is connected to the CAN data link. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
Illustration 3 g01269470
P1 terminals that are associated with the CAN data link
(P1-34) CAN data link −
(P1-50) CAN data link +
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the CAN data link.
Check the allen head screw on each ECM connector for the proper torque. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the allen head screw on the customer connector for the proper torque. Refer to the diagnostic functional test 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.STOPTest Step 2. Verify the Proper Installation of the CAN Data Link
Disconnect any module that is connected to the CAN data link.
Disconnect the P1 connector and measure the resistance between terminals P1-50 (CAN data link +) and P1-34 (CAN data link -). Expected Result:The resistance is between 57 and 63 Ohms.Results:
OK - The resistance is between 57 and 63 Ohms.Repair: If the CAN data link is working properly at this time, there may be an intermittent problem. If the problem is intermittent, refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".STOP
Not OK - The resistance is between 114 and 126. The 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 the appropriate electrical schematic in order to determine the missing resistor. Replace the missing 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.
Table 1
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 Expected Result:Each check of the resistance indicates an open circuit.Results:
OK - Each check of the resistance indicates an open circuit. 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.STOPTest 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 terminals G and F on the service tool connector.
Measure the resistance between terminals P1-50 (CAN data link +) and P1-34 (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.Repair: If the problem is intermittent, perform the diagnostic functional test Troubleshooting, "Electrical Connectors Inspect".STOP
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.STOP