78690 Mariner GASKET, RELIEF VALVE PLATE

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Schematic for the engine pressure sensorsTest Step 1. Inspect the Electrical Connectors and Wiring
Remove the electrical power from the ECM.
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A typical right side view of the engine (1) Fuel pressure sensor (2) Turbocharger inlet pressure sensor
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A typical left side view of the engine (3) Injection actuation pressure sensor (4) Intake manifold (boost) pressure sensor (5) Atmospheric pressure sensor (6) J2/P2 connectors (7) J1/P1 connectors (8) Engine oil pressure sensor
Thoroughly inspect connectors (6) and (7). Thoroughly inspect the connectors for each engine pressure sensor. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
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P2 connector (P2-15) Intake manifold (boost) pressure sensor (P2-17) Sensor return (P2-54) Sensor return (P2-28) Engine oil pressure sensor (P2-40) Fuel pressure sensor (P2-57) Atmospheric pressure sensor (P2-85) Injection actuation pressure sensor (P2-72) +5 V Supply (P2-80) +5 V Supply
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P1 connector (P1-2) +5 VDC (P1-3) Return (P1-15) Right turbo inlet pressure sensor
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Connectors for the sensors (A) Supply (B) Return (C) Signal
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the engine pressure sensors.
Check the torque of the allen head screws for the ECM connectors. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
Check the harness and wiring for abrasions and for pinch points from each sensor back 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 harness and wiring are OK. Proceed to Test Step 2.
Not OK - There is a problem in the wiring and/or the connectors.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 problem is resolved.STOPTest Step 2. Check the Voltage on the +5 V Supply Wire
Remove the electrical power from the ECM.
Disconnect the harness connectors for the following sensors:
Injection actuation pressure sensor
Intake manifold (boost) pressure sensor
Atmospheric pressure sensor
Fuel pressure sensor
Engine oil pressure sensor
Right turbo inlet pressure sensor
Restore the electrical power to the ECM.
Measure the voltage between terminals A (+5 VDC) and B (Return) at each sensor connector on the engine harness.
Remove the electrical power from the ECM.
Connect all of the sensors.Expected Result:Each voltage measurement is 5.0 0.2 VDC.Results:
OK - Each voltage measurement is 5.0 0.2 VDC. Proceed to Test Step 3.
Not OK - At least one voltage measurement is not 5.0 0.20 VDC.Repair: Refer to the diagnostic functional test Troubleshooting, "5 Volt Engine Pressure Sensor Supply Circuit - Test".STOPTest Step 3. Check for Active Diagnostic Codes
Connect the Caterpillar Electronic Technician (ET) to the service tool connector. Refer to electronic troubleshooting Troubleshooting, "Electronic Service Tools".
Restore the electrical power to the ECM.
Observe the "Active Diagnostic" screen on Cat ET. Wait at least 30 seconds so that any codes may become active. Look for an active diagnostic code for an engine pressure sensor.
Determine if the problem is related to a 03 diagnostic, a 04 code, or a 10 diagnostic code.Expected Result:No diagnostic codes are active.Results:
OK - No diagnostic codes are active for the engine pressure sensors.Repair: If any of the above codes are logged and the engine is not running proper