827478M Mercury DIAPHRAGM

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Schematic for the 5 volt pressure sensor supplyTest Step 1. Inspect the Electrical Connectors and the Wiring
Remove electrical power from the ECM.
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Right side engine view and left side engine view (1) J2/P2 ECM connector (2) J1/P1 ECM connector (3) Fuel pressure sensor (4) Engine oil pressure sensor (5) Atmospheric pressure sensor (6) Boost pressure sensor (7) J61 customer connector
Thoroughly inspect connectors (1) , (2) , and (7) . Also, thoroughly inspect the connectors for each pressure sensor. Refer to Troubleshooting, "Electrical Connectors - Inspect".
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P2 terminal locations (P2-15) Boost pressure (P2-17) Sensor return (P2-28) Engine oil pressure (P2-40) Fuel pressure (P2-57) Atmospheric pressure (P2-72) +5 V supply
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P1 ECM connector (P1-2) +5 V supply (P1-3) Sensor return (P1-15) Auxiliary pressure
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Terminal locations at the P61 customer connector (Terminal 14) +5 V supply (Terminal 15) Sensor return (Terminal 33) Auxiliary pressure
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Sensor connector (Terminal A) +5 V supply (Terminal B) Sensor return (Terminal C) Sensor signal
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connectors that are associated with the circuit.
Check the allen head screw of each ECM connector and the customer connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and wiring for abrasion and for pinch points from the pressure sensors back to the ECM.Expected Result:All connectors, pins and sockets are completely coupled and/or inserted and the harness and wiring are free of corrosion, of abrasion or of pinch points.Results:
OK - The harness and connectors appear to be OK. Proceed to Test Step 2.
Not OK - There is a problem with 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. Refer to Troubleshooting, "Electronic Service Tools".
Restore electrical power to the ECM.
Monitor the active diagnostic code screen on Cat ET. Check for an active 262-03 code and an active 262-04 code.Note: Wait at least 30 seconds in order for the diagnostic codes to become active.
Remove electrical power from the ECM.Expected Result:No diagnostic codes are active.Results:
OK - No diagnostic codes are active.Repair: If any of the above codes are logged and the engine is not running properly, refer to Troubleshooting, "Troubleshooting Without a Diagnostic Code".If the engine is running properly at this time, there may be an intermittent problem in a harness that is causing the codes to be logged. Refer to Troubleshooting, "Electrical Connectors - Inspect".STOP
Not OK - Either the 262-03 or 262-04 diagnostic code is active at this time. Proceed to Test Step 3.Test Step 3. Disconnect the Pressure Sensors and Check for Active Diagnostic Codes
Restore electrical power to the ECM.
Monitor the active diagnostic code screen on Cat ET while you disconnect each pressure sensor connector. Check for an active 262-03 code or an active 262-04 code.Note: Wait at least 30 seconds in order for the diagnostic codes to become active.
Disconnect the following sensors one at a time:
Atmospheric pressure sensor
Boost pressure sensor
Engine oil pressure sensor
Fuel pressure sensor
Auxiliary pressure sensorRemove electrical power from the ECM.Expected Result:The diagnostic code deactivates when a particular sensor is disconnected.Results:
OK - The 262-03 or 262-04 diagnostic code deactivates when a particular sensor is disconnected.Repair: Connect the suspect sensor. If the code returns, replace the sensor. Connect all of the connectors. Verify that the problem is resolved.STOP
Not OK - The 262-03 or 262-04 diagnostic code remains active after all of the sensors are disconnected. The sensors are not the cause of the diagnostic code. Leave the sensors disconnected. Proceed to Test Step 4.Test Step 4. Check the Supply Voltage at the ECM
Disconnect the J1/P1 ECM connectors.
Disconnect the J2/P2 ECM connectors.
Fabricate four jumper wires that are long enough to be used as test leads at the ECM connectors. Crimp connector sockets to one end of each jumper wire.
Remove the wires from terminal locations P1-2 (5 V sensor supply) and P1-3 (sensor return). Install a j