78438 Mariner STUD

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Schematic for the engine pressure sensorsTest Step 1. Inspect the Electrical Connectors and the Wiring
Remove electrical power from the ECM.
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Locations of the pressure sensors (typical left side engine view) (1) Intake manifold pressure sensor (2) Atmospheric pressure sensor (3) Engine oil pressure sensor (4) Fuel pressure sensor (5) J2/P2 ECM connector (6) J1/P1 ECM connector
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Location of the turbocharger inlet pressure sensor (7) Turbocharger inlet pressure sensor
Thoroughly inspect connectors (5) and (6). Also, thoroughly inspect the connectors for sensors (1), (2), (3), (4), and (7). Refer to Troubleshooting, "Electrical Connectors - Inspect".
Illustration 4 g01204484
P2 ECM connector (P2-15) Intake manifold pressure sensor (P2-17) Sensor return (P2-28) Engine oil pressure sensor (P2-40) Fuel pressure sensor (P2-57) Atmospheric pressure sensor (P2-72) +5 V supply
Illustration 5 g01218807
P1 ECM connector (P1-2) +5 V supply (P1-3) Sensor return (P1-15) Right turbocharger inlet pressure
Illustration 6 g01159881
Harness connector for the engine pressure sensors (A) Sensor supply (B) Sensor return (C) Sensor signal
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector and the sensor connectors that are associated with the active diagnostic code.
Check the allen head screw for each of the ECM connectors 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 abrasions and for pinch points from each of the pressure sensors 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 appear to be OK. Proceed to Test Step 5.
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 for each of the connectors are properly in place and ensure that the connectors are completely coupled. Verify that the repair eliminates the problem.STOPTest Step 2. Check the Supply Voltage at the Sensor Connector
Remove electrical power from the ECM.
Disconnect all of the following analog sensors at the sensor connector:
Atmospheric pressure sensor
Intake manifold pressure sensor
Engine oil pressure sensor
Fuel pressure sensor
Turbocharger inlet pressure sensor
Restore electrical power to the ECM.Note: The original diagnostic code may become inactive. An open circuit diagnostic code for the sensor supply may become active when all of the sensors are disconnected. Ignore any active codes at this time and continue with this test step.Note: Be sure to wiggle the harness during the following measurements in order to reveal an intermittent condition.
Measure the voltage between terminals A and B at each sensor connector on the engine harness.
Remove 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. The voltage is correct at the sensor connectors. Proceed to Test Step 3.
Not OK - At least one voltage measurement is not 5.0 0.2 VDC.Repair: The voltage is incorrect. There may be a problem with the sensor supply circuit. Refer to Troubleshooting, "5 Volt Engine Pressure Sensor Supply Circuit - Test" for information that is related to troubleshooting the circuit.STOPTest Step 3. Check for Active Diagnostic Codes
Connect Caterpillar Electronic Technician (ET) to the service tool connector.
Restore electrical power to the ECM.
Monitor the active diagnostic code screen on Cat ET. Look for an active diagnostic code for an engine pressure sensor.Note: Wait at least 30 seconds so that any codes may become active.
Determine if the problem is related to an open circuit diagnostic code (03) or a short circuit diagnostic code (04).Expected Result:No diagnostic codes are activ