WASHER 4B4279 - Caterpillar

System Operation Description:The Generator Set Control (GSC+) uses the Air Shutoff Relay (ASR) to activate the air shutoff solenoid during a shutdown fault. The ASR is located within the relay module. The air shutoff solenoid is located within the air inlet system of the engine.The GSC+ activates the ASR for some active shutdown faults.Note: Whenever the GSC+ activates or the GSC+ attempts to activate the ASR, "K6" is shown on the lower display. When the ASR is not activated, "K6" is not shown.There are three conditions which cause the GSC+ to activate the air shutoff relay. The first condition occurs when the operator initiates a remote shutdown. If the remote emergency stop button is activated, the fuel is shut off and the air shutoff relay is activated. The second condition occurs for an engine overspeed. The third condition is for a speed sensor fault.Note: The Generator Set has a jumper wire between terminals 6 and 9 on the Engine Control Switch (ECS). This jumper wire provides power to the Generator Set Control (GSC+) when the battery disconnect switch is closed and the ECS is in the OFF/RESET position. Unless a timer is installed in the circuit, this jumper wire also provides power to the key switch input of the engine ECM when the battery disconnect switch is closed and the ECS is in the OFF/RESET position. The timer interrupts power to the key switch input of the engine ECM when the battery disconnect switch is closed and the ECS is in the OFF/RESET position. Cycling power to the key switch input of the ECM will reset the ECM and all active diagnostic codes. The bottom dial on the timer should be set to 0.7. The middle dial on the timer should be set to 3 seconds. The top dial on the timer should be set to E.
Illustration 1 g00835234
Test Step 1. Check for Connector Damage.
Verify that the circuit breakers are not tripped.
Turn the battery disconnect switch to the OFF position.
Turn the ECS to the OFF/RESET position.
Check connectors and wiring for the following problems: damage, corrosion, abrasion and incorrect attachment.Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted. The harness and wiring should be free of corrosion, of abrasion or of pinch points.Results:
OK - The connectors and wiring are okay. Proceed to test step 2.
Not OK - The connectors and/or wiring are not okay.Repair: Repair the connectors or wiring and/or replace the connectors or wiring.STOPTest Step 2. Check the Voltage to the Coil of the Air Shutoff Relay.
Connect a voltmeter between terminal 4 and terminal 3 on the air shutoff relay.
Turn the circuit breaker for the battery to the ON position.
Turn the ECS to the STOP position.
Activate the Emergency stop push button.
Measure the voltage across the coil of the air shutoff relay.
Turn the ECS to the OFF/RESET position.
Deactivate the Emergency stop push button.
Turn the circuit breaker for the battery to the OFF position.Expected Result:The voltage should measure 24 3 VDC.Results:
OK - The voltage measures 24 3