BUSHING 1T0278 - Caterpillar

Overview
The Engine Air System Verification Test is an automated test that helps in the troubleshooting of certain problems with the following systems: Clean Gas Induction System (CGI), combustion air supply and variable nozzle turbocharger. Table 1 lists the problems for each system.
Table 1
Systems and Problems    
System    Problems    
CGI     Electrical problems with the circuit for the CGI control group    
Low flow of CGI
High flow of CGI
Combustion Air Supply     Low flow of combustion air    
High flow of combustion air
Erratic flow of combustion air
Variable Nozzle Turbocharger     Excessive turbocharger speed    The problems that are listed in Table 1 can cause the following symptoms:
Boost pressure may be incorrect
The ARD may fail to ignite
The ARD may experience a loss of combustion
There may be high turbocharger speed on C7 engines or C9 enginesThe test is performed when the vehicle is stationary and the engine is running. Approximately two minutes are required in order for the test to run. The Caterpillar Electronic Technician (ET) commands the following components to actuate during the test:
CGI control group
Air pressure control valve
Variable nozzle turbocharger on C7 engines and C9 enginesCat ET monitors the following sensors during the test:
Differential pressure sensor for the CGI system
Absolute pressure sensor for the CGI system
Temperature sensor for the CGI system
Differential pressure sensor for the combustion air system
Intake manifold pressure sensor
Turbocharger speed on C7 engines and C9 enginesCat ET displays the results of the test after the test is complete. The test results must be interpreted in order to determine if troubleshooting is required.Starting the Test
The test will not start until the following conditions are met:
The vehicle must be stopped.
The engine must be running.
All engine driven accessories must be off.
The coolant temperature must be above 65 °C (149 °F).
Certain sensors and actuators do not have diagnostic codes.The engine speed must be approximately 1400 rpm during the test. It may be necessary to manually raise the engine speed with the cruise control switches or the accelerator pedal. The test will abort for the following conditions:
The user aborts the test.
The vehicle speed is above zero.
Engine speed is too high or too low.
Engine load is excessive or inconsistent.
Diagnostic codes for certain sensors and actuatorsEnding the Test
The test ends automatically. The test results are displayed on Cat ET at the end of the test. The test results may be printed or the test results may be saved to a file on the hard disk. The file may be attached to a warranty report.Test Points
The test is a series of test points. The test points are described in Table 2. Cat ET collects data for approximately 20 seconds at each test point. Then, Cat ET moves to the next test point.
Table 2
Test Points    
Test Point    System That is Being Tested    Position of the Component    
1     "CGI Test"     The CGI valve is