STUD-TAPERLOCK 1J8668 - Caterpillar

System Operation Description:The Electronic Control Module (ECM) has the ability to stop the engine by shutting off the inlet air supply in an emergency situation. The ECM activates a relay which energizes the air shutoff solenoid. The solenoid actuates the air shutoff valve.There are two conditions which can cause the ECM to activate the air shutoff relay. The first condition occurs when the operator activates the remote emergency stop button. When the emergency shutdown is recognized, the ECM will stop the injection of fuel and the air shutoff relay is activated. The ECM will hold the relay active for 1.5 seconds. The second condition occurs when the ECM detects an engine overspeed. This is simulated when the overspeed verify switch is activated. When the engine speed reaches 75 percent of the programmed overspeed setpoint, the ECM will activate the air shutoff relay. The second condition can also occur when a test of the air shutoff relay is made. Again, this is used for testing purposes.Regardless of the reason for the activation, the engine control switch (ECS) must be turned to the OFF/RESET position for at least three seconds. Turning the ECS to the OFF/RESET position will reset the engine control. Also, turning the ECS to the OFF/RESET position will reset the relay that operates the air shutoff relay.
Illustration 1 g01067849
Schematic for the air shutoff systemTest Step 1. Check the Electrical Connectors and the Wiring
Verify that the air shutoff valves are set to the Open position.
Thoroughly inspect the ECM connector J1/P1, and the customer connector. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit for the remote shutdown switch.
Check the ECM connector (allen head screw) for the proper torque of 6.0 N m (55 lb in).
Check the customer connector (allen head screw) for the proper torque of 2.25 0.25 N m (20 2 lb in).
Check the harness and the wiring for abrasion and for pinch points from the air shutoff solenoid to the ECM. Refer to Illustration 1.Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted, and the harness and wiring are free of corrosion, of abrasion and of pinch points.Results:
OK - Proceed to Test Step 2.
Not OK - Repair the wiring and connectors or replace the wiring or the connectors. Ensure that all of the seals are properly connected. Verify that the repair eliminates the problem. Stop.Test Step 2. Test the Output of the Air Shutoff Relay
Turn the circuit breaker for the battery to the ON position.
Turn the ECS to the STOP position.
Connect the Caterpillar Electronic Technician (ET) to the service tool connector.
Access the "Override Parameters" screen on Cat ET.
Disable the "Air Shutoff Override".Expected Result:The air shutoff relay activates. Results:
OK - The relay and the solenoid for the air shutoff system are operating properly at this time. There may be an intermittent electrical problem in the air shutoff circuit.Repair: Refer to Troubleshooting, "Electrical