GASKET 7W8401 - Caterpillar

System Operation Description:The emergency stop switch sends two signals to the ECM. The signal is used to determine if the emergency stop switch is active.The emergency stop switch is active, when the signals are open.The emergency stop switch is inactive, when the signals are closed.When a signal from the emergency stop switch is received, the ECM will activate the air shutoff solenoid.The engine will not be able to start when the emergency stop switch is activated.The engine will not start until the engine rpm equals 0. The engine will not start until the emergency stop switch is closed. The engine will not start until the power to the ECM has been reset.
Illustration 1 g00598807
SchematicTest Step 1. Check for Connector Damage
Turn the circuit breaker for the battery to the OFF position.
Turn the ECS to the OFF/RESET position.
Check connectors and associated wiring for the following problems: damage, corrosion, abrasion and incorrect attachment.Expected Result:The connectors and wiring should be free of the following problems: damage, corrosion, abrasion and incorrect attachment.Results:
OK - Proceed to test step 2.
Not OK - Repair: Repair the connectors and/or wiring or replace the connectors and/or wiring. Stop.Test Step 2. Check the Status of the Switch.
Turn the circuit breaker for the battery to the ON position.
Turn the ECS to the STOP position.
Activate the emergency stop switch.
Connect the ET.
Observe the status of the emergency stop switch on the ET.Expected Result:The parameter for the emergency stop switch should read "ON".Results:
OK - The emergency stop switch is working correctly. Proceed to test step 3.
Not OK - The parameter for the emergency stop switch does not display "ON". Proceed to test step 4.Test Step 3. Check the Status of the Switch.
Deactivate the emergency stop switch.Expected Result:The parameter for the emergency stop switch should read "OFF".Results:
OK - The emergency stop switch is functioning correctly. Stop.
Not OK - The parameter for the emergency stop switch does not display "OFF". Proceed to test step 4.Test Step 4. Test the ECM.
Turn the ECS to the OFF/RESET position.
Disconnect P1 from the ECM. Remove P1-29, P1-02 and P1-24.
Locate a suitable jumper wire.
Insert the jumper wire at P1. Connect P1-02 and P1-24 to P1-29.
Turn the ECS to the STOP position.
Observe the parameters for the emergency stop on the ET.
Turn the ECS to the OFF/RESET position. Remove the jumper wire and reinstall all wires.Expected Result:The parameter for the emergency stop switch should display "OFF" when the jumper is installed. The parameter for the emergency stop switch should display "ON" when the jumper is removed.Results:
OK - The problem is not with the ECM. Proceed to test step 5.
Not OK - Repair: Replace the ECM. Refer to Troubleshooting, "Replacing the ECM". Stop.Test Step 5. Check the Switches and the Wiring.
Turn the ECS to the OFF/RESET position.
Activate the emergency stop switch.
Measure the resistance between P1-29 and P1-02.
Measure the resistance between P1-29 and P1-24.Expected Result:The resistance should be greater than 20,000 Ohms.Results:
OK - The resistance is greater than 20,000 Ohms. Proceed to test step 6.
Not OK - The resistance is less than 20,000 Ohm. There