825448 Mercury SCREW-VALVE ADJUSTING

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Schematic for the engine temperature sensors
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P2 terminals that are associated with the engine temperature sensors (P2-18) Sensor return (P2-32) Engine coolant temperature (P2-34) Engine oil temperature (P2-35) Intake manifold air temperature
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Harness connector for the temperature sensors (Terminal 1) Signal (Terminal 2) ReturnTest Step 1. Inspect the Electrical Connectors and the Wiring
Remove electrical power from the engine ECM.
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Left side engine view (1) Engine coolant temperature sensor (2) Engine oil temperature sensor (3) Intake manifold air temperature sensor
Inspect the connectors for sensors (1), (2), and (3). Refer to Troubleshooting, "Electrical Connectors - Inspect".
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the temperature sensors.
Check the allen head screw on each ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and wiring for abrasions and for pinch points from each sensor to the ECM.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 connectors and wiring appear to be OK. Proceed to Test Step 2.
Not OK - There is a problem in the connectors and/or wiring.Repair: Repair the wiring and/or the connectors. 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 repair eliminates the problem.STOPTest Step 2. Check for Active Diagnostic Codes
Connect Caterpillar Electronic Technician (ET) to the service tool connector.
Restore electrical power to the engine ECM.
Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.Note: Wait at least 30 seconds in order for the diagnostic codes to become active.
Look for a 03 diagnostic code or a 04 diagnostic code.Expected Result:No diagnostic codes are active.Results:
OK - No diagnostic codes are active. The problem appears to be resolved.Repair: The problem may have been related to a faulty connection in the harness. Carefully reinspect the connectors and wiring. Refer to Troubleshooting, "Electrical Connectors - Inspect" for additional information.STOP
Not OK - A 04 diagnostic code is active at this time. Proceed to Test Step 3.
Not OK - A 03 diagnostic code is active at this time. Proceed to Test Step 4.Test Step 3. Disconnect the Suspect Sensor in Order to Create an Open Circuit
Remove electrical power from the engine ECM.
Disconnect the suspect sensor from the engine harness.
Restore electrical power to the engine ECM.
Access the "Active Diagnostic Codes" screen on Cat ET and check for an active 03 diagnostic code for the suspect sensor.Note: Wait at least 30 seconds in order for the diagnostic codes to become active.
Remove electrical power from the engine ECM.Expected Result:A 03 diagnostic code is now active for the suspect sensor.Results:
OK - A 04 diagnostic code was active before disconnecting the sensor. A 03 diagnostic code became active after the sensor was disconnected. There may be a problem with the sensor.Repair: Temporarily connect a new sensor to the harness, but do not install the new sensor in the engine. Verify that there are no active diagnostic codes for the new sensor. If there are no active diagnostic codes for the sensor, permanently install the new sensor. Clear any logged diagnostic codes. Verify that the repair eliminates the problem.STOP
Not OK - The 04 diagnostic code is still present. Leave the sensor disconnected. Proceed to Test Step 5.Test Step 4. Create a Short at the Sensor Connector
Remove electrical power from the engine ECM.
Disconnect the suspect sensor at the sensor connector.
Fabricate a jumper wire that can be used to create a short between terminal 1 (signal) and terminal 2 (sensor return) at the suspect sensor's connector. Crimp connector pins to each end of the jumper wire.
Install the jumper into the harness side of the sensor connector.
Restore electrical power to the engine ECM.
Access the "Active Diagnostic Code" screen on Cat ET. Check for an active 04 diagnostic code for the suspect sensor.Note: Wait at least 30 seconds in order for the diagnostic codes to become active.
Remove electrical power from the engine ECM.Expected Result:A 04 diagnostic code is now active for the suspect sensor.Results:
OK - A 03 diagnostic code was active before creating the short at the sensor connector. A 04 diagnostic code became active after creating the short at the sensor connector.Repair: Temporarily connect a new sensor to the harness, but do not install the new sensor in the engine. Verify that there are no active diagnostic codes for the new sensor. If there are no active diagnostic codes for the sensor, permanently install the new sensor. Clear any logged diagnostic codes.STOP
Not OK - A 03 diagnostic code is still active for the suspect sensors. Proceed to Test Step 5.Test Step 5. Check the Operation of the ECM
Remove electrical power from the engine ECM.
Check the operation of the ECM by creating an open at the ECM.