PIN AS 2343803 - Caterpillar

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 (0.4 psi) of each other.Results:
Yes - The readings from all of the sensors are within 3 kPa (0.4 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 (2.2 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 (0.4 psi) and by less than 15 kPa (2.2 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 (0.3 psi) and the turbocharger inlet pressure is not reduced by more than 7.5 kPa (1.1 psi).Results:
OK - During operation from low idle to high load, the atmospheric pressure does not vary by more than 2 kPa (0.3 psi) and the turbocharger inlet pressure is not reduced by more than 7.5 kPa (1.1 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 (0.3 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 (1.1 psi).Repair: The inlet air restriction is excessive. Inspect all of the inlet air system for restriction. Make repairs, as needed.STOP