79023A90 Mercury FUSE ASSEMBLY (90 AMP.)

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Schematic
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P2 ECM connectorTest Step 1. Verify all Active Diagnostic Codes
Connect the electronic service tool to the service tool connector.
Turn the keyswitch to the ON position. Wait at least 15 seconds for activation of the diagnostic codes.
Monitor the "Active Diagnostic Codes" screen on the electronic service tool.Expected Result:There is an active diagnostic code for one or more of the temperature sensors.Results:
Yes - There is an active diagnostic code for one or more of the temperature sensors. Proceed to Test Step 2.
No - There are no active diagnostic codes for the temperature sensors.Repair: If there are logged diagnostic codes for one or more of the temperature sensors and the engine is not running properly, refer to Troubleshooting, "Troubleshooting without a Diagnostic Code". If the engine is running properly at this time, an intermittent condition may be causing the logged codes. Refer to Troubleshooting, "Electrical Connectors - Inspect". Stop.Test Step 2. Inspect Electrical Connectors and Wiring
Thoroughly inspect the J1/P1 ECM connector, the J2/P2 ECM connector, the suspect sensor connector, and any other connectors in the circuit. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Perform a 45 N (10 lb) pull test on each of the wires in the sensor connector and the ECM connector that are associated with the active diagnostic code.
Verify that the latch tab of the connector is properly latched.
Check the ECM connector (allen head screw) for the proper torque of 6.0 N m (55 lb in).
Check the harness and wiring for abrasions and for pinch points from the sensor to the ECM.Expected Result:All connectors, pins, and sockets should be completely coupled and/or inserted. The harness and wiring should be free of corrosion, abrasion, and pinch points.Results:
OK - Proceed to Test Step 3.
Not OK - Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.Verify that the repair eliminates the problem. Stop.Test Step 3. Verify that the Diagnostic Code is Still Active
Turn the keyswitch to the ON position. Wait at least 15 seconds for activation of the diagnostic codes.
Access the "Active Diagnostic Codes" screen on the electronic service tool and check for active diagnostic codes.
Determine if the problem is related to an open circuit diagnostic code or a short circuit diagnostic code.Expected Result:A short circuit diagnostic code or an open circuit diagnostic code is active.Results:
Short Circuit - A short circuit diagnostic code is active at this time. Proceed to Test Step 4.
Open Circuit - An open circuit diagnostic code is active at this time. Proceed to Test Step 6.
No Active Diagnostic Codes - There is a problem in the connectors and/or the wiring.Repair: Carefully reinspect the connectors and wiring. The diagnostic code will probably reoccur. Refer to Troubleshooting, "Electrical Connectors - Inspect" for additional information. Stop.Test Step 4. Disconnect the Sensor in Order to Create an Open Circuit
Turn the keyswitch to the OFF/RESET position.
Disconnect the connector to the sensor with the short circuit diagnostic code.
Turn the keyswitch to the ON position. Wait at least 15 seconds for activation of the diagnostic codes.
Access the "Active Diagnostic Codes" screen on the electronic service tool and check for an active open circuit diagnostic code for the suspect sensor.Expected Result:An open circuit diagnostic code is now active for the disconnected sensor.Results:
OK - A short circuit diagnostic code was active before disconnecting the sensor. An open circuit diagnostic code became active after disconnecting the sensor. Proceed to Test Step 5.
Not OK - There is a short circuit between the sensor harness connector and the ECM. Leave the sensor disconnected. Proceed to Test Step 7.Test Step 5. Determine if the Short Circuit is in the Connector or in the Sensor
Thoroughly inspect the connector for moisture.
Inspect the seals and reconnect the sensor.
If the short circuit diagnostic code reappears, the sensor is the problem.
Temporarily connect a new sensor to the harness, but do not install the new sensor in the engine.
Check for a short circuit diagnostic code while the new sensor is connected.Expected Result:The short circuit diagnostic code is not present when a new sensor is connected.Results:
OK - The suspect sensor had an internal short.Repair: Permanently install the new sensor and clear any logged diagnostic codes.Verify that the repair eliminates the problem. Stop.
Not OK - The connector is shorted.Repair: Repair the connector. Stop.Test Step 6. Short the Sensor Connector
Turn the keyswitch to the ON position.
Unplug the suspect sensor.Note: Monitor the "Active Diagnostic Codes" screen on the electronic service tool before installing the jumper wire and after installing the jumper wire.
Install a jumper wire with Deutsch sockets on each end between the terminals on the plug for the suspect sensor. Wait at least 15 seconds for activation of the short circuit diagnostic code.
Remove the jumper wire.Expected Result:A short circuit diagnostic code is active when the jumper wire is installed. An open circuit diagnostic code is active when the jumper wire is removed.Results:
OK - The engine harness and the ECM are OK.Repair: Perform the following repair:
Temporarily reconnect the suspect sensor.
If the diagnostic code remains active, replace the sensor.
Verify that the repair eliminates the problem.
Clear all logged diagnostic codes. Stop.
Not OK - The open circuit diagnostic code remains active with the jumper in place. There appears to be an open circuit between the ECM and the sensor. Proceed to Test Step 7.Test Step 7. Check the Operation of the ECM by Creating Open And Short Circuits at the ECM Connector
Turn the keyswitch to the OFF/RESET position.
Disconnect the P2 ECM connector. Thoroughly inspect both halves of the connector for signs of corrosion and/or moisture.
Reconnect the ECM connector.
Turn the keyswitch to the ON position. Monitor the "Active Diagnostic Code" screen on the electronic service tool. Wait at least 15 seconds for activation of the code.An open circuit diagnostic code should be active for the suspect sensor. Note the sensor that has the open circuit diagnostic code.
Remove the signal wire and the return wire for the suspect sensor from the P2 ECM connector.Note: Active open circuit diagnostic codes will be