EDGE-CUTTING 6Y5538 - Caterpillar

System Operation Description:The air inlet shutoff is available for certain engine ratings that operate in areas with large amounts of combustible gases. When an overspeed is detected, a relay activates the air inlet shutoff system and fuel injection is disabled. This is accomplished by activation of a solenoid that closes a flap that is in the inlet air system in order to cut off the air supply to the engine. Once the air inlet shutoff is activated the flap must be manually reset to the open position, before the engine can be restarted."Air Inlet Shutoff System Control Test"Caterpillar Electronic Technician (ET) allows the use of the "Air Inlet Shutoff System Control Test" in order to test the air inlet shutoff system. This test will determine if the air inlet shutoff system is working correctly. When the test is activated the air inlet shutoff will activate and the engine will shut down. The engine speed must be 1500 rpm 100 rpm and the transmission must be in neutral before this test can be used."Air Inlet Shutoff Relay Output"The "Air Inlet Shutoff Relay Output" test is available to energize the air inlet shutoff relay. When the test is activated, a one second pulse is sent to the air inlet shutoff relay. The engine speed must be 0 rpm and the transmission must be in neutral before this test can be used.Air Inlet Shutoff SwitchThe air inlet shutoff switch can be used to manually activate the air inlet shutoff. When the switch is depressed, a one second pulse is sent to the air inlet shutoff relay. The transmission must be in neutral before the air inlet shutoff switch will become active.
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Schematic for the air inlet shutoff circuit
Test Step 1. Perform the "Air Inlet Shutoff System Control Test"
Turn the keyswitch to the OFF position.
Connect Cat ET to the service tool connector.
Turn the keyswitch to the ON position.
Place the transmission in the neutral position.
Start the engine. Increase the engine speed from low idle to 1500 rpm 100 rpm.
Access the "Air Inlet Shutoff System Control Test" in the "Diagnostic Tests" under the "Diagnostics" menu on Cat ET.
Start the test.
Wait for the engine to stop.
Stop the test. Expected Result:Fuel injection is disabled. The air inlet shutoff is activated and the engine is shutdown.Results:
OK - The engine is shutdown when the "Air Inlet Shutoff System Control Test" is activated.Repair: The air inlet shutoff is working correctly. Reset the air inlet shutoff system.Proceed to Test Step 2.
Not OK - The engine did not shut down. Proceed to Test Step 4.Test Step 2. Check the Air Inlet Shutoff Switch
Turn the keyswitch to the ON position.
Use Cat ET to monitor the status for the air inlet shutoff switch while the switch is depressed. Expected Result:The switch status reports "On" when the switch is depressed. The status reports "Off" when the switch is released.Results:
OK - The switch status reports "On" when the switch is depressed. The status reports "Off" when the switch is released.Repair: The switch is