5031474 JOHNSON TRIM, SENDER

System Response:The 172-1 event code will be logged.The 172-2 event code will be logged.Possible Performance Effect:172-1None172-2The engine power will be derated.Troubleshooting:There may be a problem with the air cleaner.Test Step 1. Check the Air FiltersClean plugged air filters or replace plugged air filters. Refer to the Operation and Maintenance Manual. Ensure that the repair eliminates the problem.Results:
OK - STOP
Not OK - Proceed to Test Step 2.Test Step 2. Inspect the Sensors, the Wiring, and the Electrical ConnectorsInspect the atmospheric pressure sensor and the turbocharger inlet pressure sensor for proper installation.Inspect all of the wiring and the connectors that are associated with the sensors. Refer to the engine's Electrical Schematic and refer to Troubleshooting, "Electrical Connectors - Inspect". Ensure that all of the wiring and the connectors are in good condition.Expected Result:The sensors are properly installed. 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 sensors, the wiring, and the connectors are OK. Proceed to Test Step 3.
Not OK - There is a problem with a sensor, with the wiring, or with a connector.Repair: Make the necessary corrections. Replace parts, if necessary. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.STOPTest Step 3. Check for Active Diagnostic Codes
Connect the Caterpillar Electronic Technician (ET) to the service tool connector.
Turn ON the power to the ECM but do not start the engine.
Check for active diagnostic codes that are related to the atmospheric pressure sensor and/or to the turbocharger inlet pressure sensor. Expected Result:There are no active diagnostic codes that are related to the atmospheric pressure sensor or to the turbocharger inlet pressure sensor.Results:
OK - There are no active diagnostic codes that are related to the atmospheric pressure sensor or to the turbocharger inlet pressure sensor. Proceed to Test Step 4.
Not OK - There is at least one active diagnostic code that is related to the atmospheric pressure sensor or to the turbocharger inlet pressure sensor.Repair: Troubleshoot the active diagnostic code before continuing with this procedure.STOPTest Step 4. Monitor the Air Filter Restriction with the Engine Stopped
Verify that the power to the ECM is ON with the engine stopped.
Use Cat ET to monitor the air filter restriction. Expected Result:The air filter restriction is less than 1 kPa (4 inches of H2O).Results:
OK - The air filter restriction is less than 1 kPa (4 inches of H2O). Proceed to Test Step 6.
Not OK - The air filter restriction is greater than 1 kPa (4 inches of H2O). Proceed to Test Step 5.Test Step 5. Compare the Readings from the Pressure Sensors
Verify that the power to the ECM is ON, that Cat ET is communicating with the ECM, and that the engine is stopped.
Use Cat ET to compare the readings from the atmospheric pressure sensor, the turbocharger inlet pressure sensor, and the turbocharger outlet pressure sensor. Record the readings in Table 1.
Table 1
Readings from the Pressure Sensors
Pressure Reading
Atmospheric
Turbocharger inlet
Turbocharger outlet Expected Result:The readings from all of the sensors are within 3 kPa (0.5 psi) of each other.Results:
Yes - The readings from all of the sensors are within 3 kPa (0.5 psi) of each other. Proceed to Test Step 6.
No - A reading from one of the sensors differs from both of the other two sensors by more than 15 kPa (2 psi).Repair: There is probably a problem with the voltage supply for the sensor that has the different reading. Troubleshoot the sensor's voltage supply. Refer to Troubleshooting, "5 Volt Engine Pressure Sensor Supply Circuit - Test".STOP
No - A reading from one of the sensors is different from the other two sensors by more than 3 kPa (0.5 psi) and by less than 15 kPa (2 psi).Repair: There is a problem with the suspect sensor. Replace the sensor. Verify that the problem is resolved.STOPTest Step 6. Run the Engine and Monitor the Readings from the Sensors for the Inlet Air Restriction
Verify that Cat ET is communicating with the ECM and start the engine.
Operate the engine according to Table 2. Record the readings from the sensors in the appropriate column.
Table 2
Readings from the Sensors for Inlet Air Restriction
Engine Operation Pressure Reading
Low idle Atmospheric
Turbocharger inlet
High idle Atmospheric
Turbocharger inlet
High load or lug Atmospheric
Turbocharger inlet Expected Result:During operation from low idle to high load, the atmospheric pressure does not vary by more than 2 kPa (0.5 psi) and the turbocharger inlet pressure is not reduced by more than 7.5 kPa (1 psi).Results:
OK - During operation from low idle to high load, the atmospheric pressure does not vary by more than 2 kPa (0.5 psi) and the turbocharger inlet pressure is not reduced by more than 7.5 kPa (1 psi).Repair: The system is operating properly at this time. If the problem is intermittent, refer to Troubleshooting, "Electrical Connectors - Inspect".STOP
Not OK - During operation from low idle to high load, the atmospheric pressure varies by more than 2 kPa (0.5 psi).Repair: The crankcase pressure is varying. Inspect the crankcase breather for clogging and/or for some obstruction. Make sure that the breather's hose is clear. If you suspect that the crankcase pressure is due to excessive blowby, use the 8T-2700 Blowby/Air Flow Indicator and refer to Special Instruction, SEHS8712, "Using the 8T-2700 Blowby/Air Flow Indicator".STOP
Not OK - During operation from low idle to high load, the turbocharger inlet pressure is reduced by more than 7.5 kPa (1 psi).Repair: The inlet air restriction is excessive. Inspect all of the inlet air system for restriction. Make repairs, as needed.STOP