DOWEL 2N5775 - Caterpillar

System Operation Description:The Electronic Control Module (ECM) attempts to perform an automatic calibration of all pressure sensors whenever the ECM is powered and the engine has been off for at least ten seconds. Cranking the engine during the first ten seconds causes the ECM to abort the calibration attempt.During an automatic pressure sensor calibration, the ECM checks all pressure sensors against an acceptable range. If any pressure sensor reading is outside the acceptable range, the previous calibration value is used. The ECM then calibrates all pressure sensors against the atmospheric pressure sensor.A pressure sensor calibration will not be successful if there are active sensor diagnostic codes with an FMI of 03 and/or 04. A pressure sensor calibration will not be successful if one of the following conditions exist:
The pressure reading is outside of an acceptable range.
The pressure reading varies significantly during calibration.Test Step 1. Check for "ACTIVE" Diagnostic Codes
Disconnect the main power.
Start Caterpillar Electronic Technician (ET).
Connect the main power.
Check for active diagnostics.Expected Result:There are no active diagnostics.Results:
OK - There are no active diagnostics. Proceed to Test Step 2.
Not OK - A pressure sensor with an active diagnostic code cannot be calibrated.Repair: Perform the appropriate troubleshooting procedure.STOPTest Step 2. Perform a Calibration of the Sensors
Select "Calibrations" from the "Service" menu on Cat ET. Select the "Pressure Sensor Calibration" from the "Calibrations" menu. The ECM will perform a pressure sensor calibration when this screen is entered.Expected Result:Cat ET indicates that the calibration was completed.Results:
OK - Cat ET indicates that the calibration was completed.Repair: Reset the system and check for active diagnostic codes.STOP
Not OK - All pressure sensors could not be calibrated. Proceed to Test Step 3.Test Step 3. Determine the Cause of Failed Calibration
Check if any pressure sensors have an active diagnostic code. A pressure sensor calibration will not be successful if there are active diagnostic codes with an FMI of 03 and/or 04.
Verify that the correct sensor has been installed.
Check the display status screen on Cat ET for the pressure sensor reading.Note: The valid range for atmospheric pressure must be between 45 kPa (6.5 psi) and 111 kPa (16 psi) for a successful calibration.Expected Result:Cat ET displays the following pressures:
Crankcase pressure is atmospheric pressure 8 kPa (1.2 psi).
Turbocharger compressor inlet pressure is atmospheric pressure 8 kPa (1.2 psi).
Turbocharger compressor outlet pressure is atmospheric pressure 15 kPa (2.2 psi).
Fuel pressure is atmospheric pressure 27 kPa (3.9 psi).
Engine oil pressure is atmospheric pressure 27 kPa (3.9 psi).Results:
OK - Repeat calibration of the sensors.Repair: Repeat the calibration. Verify that no active diagnostic codes are present.STOP
Not OK - There is a problem with the wiring harness and/or the sensor. Inspect the components for damage, for corrosion or for abrasion. Repair the components and/or replace the components.Repair: Perform the appropriate troubleshooting procedure.STOP