807172A 1 Mercruiser BASE ASSEMBLY, Fuel Filter

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Schematic for the engine temperature sensorsTest Step 1. Inspect Electrical Connectors and Wiring
Remove the electrical power from the ECM.
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Sensor locations (typical left side engine view) (1) Engine coolant temperature sensor (2) Intake manifold air temperature sensor
Thoroughly inspect the connectors for sensors (1), and (2). Also, thoroughly inspect ECM connector J2/P2. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
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P2 ECM connector (P2-13) Engine coolant temperature (P2-30) Sensor return (P2-56) Intake manifold air temperature
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Connector for the temperature sensors (1) Sensor signal (2) Sensor return
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the temperature sensors.
Check the allen head screws for each ECM connector for the proper torque. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
Check the harness and the wiring for abrasions and for pinch points from each of the temperature sensors to the ECM connector.Expected Result:All connectors, pins, and sockets are completely coupled and 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 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.STOPTest Step 2. Check for Active Diagnostic Codes
Connect the Caterpillar Electronic Technician (ET) to the service tool connector.
Restore the electrical power to the 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 the diagnostic functional test 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 the electrical power from the ECM.
Disconnect the suspect sensor from the engine harness.
Restore the electrical power to the 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 the electrical power from the 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.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 the electrical power from the 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 the electrical power to the 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 the electrical power from the ECM.
Check the operation of the ECM by creating an open at the ECM.
Disconnect the ECM connector for the suspect sensor.
Fabricate a jumper wire that is long enough to reach from a terminal at the ECM connector to the engine ground stud.