7270A 1 Mariner COVER

Illustration 1 g01242573
Schematic for the engine pressure sensorsTest Step 1. Inspect the Electrical Connectors and Wiring
Remove the electrical power from the ECM.
Illustration 2 g01199203
A typical left side view of the C7 engine (1) Fuel pressure sensor (2) Injection actuation pressure sensor (3) Atmospheric pressure sensor (4) Intake manifold (boost) pressure sensor (5) Engine oil pressure sensor (6) J2/P2 connectors (7) ECM (8) J1/P1 connectors
Thoroughly inspect connectors (6) and (8). Thoroughly inspect the connectors for each engine pressure sensor. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
Illustration 3 g01209367
P2 ECM 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
Illustration 4 g01123211
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 J204/P204
Intake manifold (boost) pressure sensor J200/P200
Atmospheric pressure sensor J203/P203
Fuel pressure sensor J209/P209
Engine oil pressure sensor J201/P201
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 code, a 04 diagnostic 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 properly, refer to troubleshooting without a diagnostic code Troubleshooting.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 the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".STOP
Active 04 code - An 04 diagnostic code is active. Proceed to Test Step 4.
Active 03 code - An 03 diagnostic code is active. Proceed to Test Step 5.Test Step 4. Disconnect the Suspect Sensor in Order to Create an Open Circuit
Remove the electrical power from the ECM.
Disconnect the sensor connector of the sensor with the 04 diagnostic code.
Restore the electrical power to the ECM. Wait at least 30 seconds for activation of the diagnostic codes.
Access the "Active Diagnostic Code" screen on Cat ET. Check for an active 03 diagnostic code for the disconnected sensor.
Remove the electrical power from the ECM.Expected Result:A 03 diagnostic code is now active for the disconnected sensor.Results:
OK - A 04 diagnostic code was active before you disconnected the sensor. A 03 diagnostic code became active after the sensor was disconnected. The harness and the ECM are OK. There may be a problem with the sensor.Repair: 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 sensor. If there are no active diagnostic codes for the sensor, permanen