3500B Locomotive Engines Caterpillar

The ECM has the ability to stop the engine by cutting off the air supply in an emergency situation. The ECM activates the air shutoff solenoid in order to close the air shutoff mechanism.

There are two conditions which cause the engine control to activate the air shutoff solenoid. The first condition occurs when the operator initiates an emergency shutdown. When the shutdown is recognized, fuel is shut off and the air shutoff solenoid is activated. The second condition is for an engine overspeed. Engine overspeed can be a real overspeed condition or an overspeed condition can be simulated by using the overspeed verify switch.

Regardless of the reason for activation, the main power to the ECM must be turned OFF for three seconds in order to reset the engine control.

Note: The Air Shutoff is optional. A programmable parameter needs to be set with the Electronic Technician (ET) in order to enable the air shutoff.

Note: Ensure that BOTH of the air shutoffs are manually reset after an Emergency Stop in order to start the engine again.

Illustration 1	g00847760

Test Step 1. Check for Connector Damage.

1. Turn the Start/Run/Stop switch to the STOP position.

2. Turn the circuit breaker for the battery to the OFF position.

3. Thoroughly inspect the ECM connectors J1/P1 and J2/P2. Inspect all of the other connectors. Refer to Troubleshooting, "Inspecting Electrical Connectors" for details.

4. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit.

5. Check the ECM connector (allen head screw) for the proper torque of 6.0 N·m (55 lb in).

6. Check the customer connector (allen head screw) for the proper torque of 2.25 ± 0.25 N·m (20 ± 2 lb in).

7. Check the harness and the wiring for abrasion and pinch points.

Expected Result:

The connectors and wiring should be free of the following problems: damage, corrosion, abrasion and incorrect attachment.

Results:

• OK - The connectors and wiring are free of any problems. Proceed to test step 2.

• Not OK - The wiring and/or connectors are in need of repair.

  Repair: Repair the wiring and/or connectors or replace the wiring and/or connectors.

  Stop.

Test Step 2. Check the Status of the Air Shutoff on the ET.

1. Connect the Electronic Technician (ET) to the service tool connector.

2. Turn the circuit breaker for the battery to the ON position.

3. Access the screen for the override on the Electronic Service Tool. Activate the override for the air shutoff.

4. Monitor the status of the air shutoff on the ET screen.

5. Deactivate the override for the air shutoff.

Expected Result:

The air shutoff solenoid should activate. The ET should indicate "ON".

Results:

• OK - The air shutoff solenoid activates.

  Repair: The air shutoff system is operating properly from the ECM to the air shutoff solenoid. The wiring and/or emergency stop switches that input a signal into the ECM may need repair. Verify that the wiring and/or the emergency stop switches are operating properly.

  Stop.

• Not OK - The air shutoff solenoid does not activate. Proceed to test step 3.

Test Step 3. Check the Output Voltage at the Solenoid.

1. Disconnect the connector at the air shutoff solenoid.

2. Connect a voltage test lamp between pins C and B at the solenoid connector.

3. Access the screen for the override on the Electronic Service Tool. Activate the override for the air shutoff.

4. Monitor the voltage test lamp between pins C and B at the solenoid connector.

5. Deactivate the override for the air shutoff.

Expected Result:

The voltage test lamp should illuminate with the override in place.

Results:

• OK - The voltage test lamp illuminated with the override in place.

  Repair: Check the connector and the wiring to the solenoid for damage. If the connector and wiring are okay install a new air shutoff solenoid. Ensure that the problem is no longer present. Verify that the system is operating properly.

  Stop.

• Not OK - The voltage test lamp did not illuminate with the override in place. Proceed to test step 4.

Test Step 4. Check the Output Voltage at the ECM.

1. Disconnect the main power.

2. Disconnect the ECM connectors J2/P2.

3. Remove wire G971-BR in socket 19 from ECM connector P2. Install a wire jumper into the socket for P2-19.

4. Reconnect ECM connector J2/P2.

5. Connect a voltage test lamp between the wire jumper in socket 19 and engine ground.

6. Access the override on the Electronic Service Tool. Activate the override for the air shutoff.

   Note: This test will cause a 446-06 CID-FMI to be logged. Be sure to delete this CID-FMI when this test is completed.

7. Monitor the voltage test lamp between the wire jumper in socket 19 and engine ground.

8. Deactivate the override for the air shutoff.

9. Disconnect the main power. Remove the wire jumper. Reinstall all wires. Reconnect ECM connector J2/P2.

Expected Result:

The voltage test lamp should illuminate with the override in place.

Results:

• OK - The voltage test lamp illuminated with the override in place. The problem appears to be in the wiring between the ECM and the air shutoff solenoid.

  Repair: Repair the wiring or replace the wiring between the ECM and the air shutoff solenoid.

  Stop.

• Not OK - The voltage test lamp did not illuminate with the override in place.

  Repair: The ECM did not output the correct voltage. Verify that the ECM is receiving the correct voltage. Refer to Troubleshooting, "Electrical Power Supply".

  Stop.