3176C, 3406E and 3456 Industrial Engines Troubleshooting – Air Shutoff – Test

Test Step 2. Test the Operation of the Control Solenoid for the Air Shutoff Relay

 

1. Remove electrical power from the ECM.

 

2. Remove the wire from the output of the air shutoff relay.

 

3. Connect a test lamp between the output of the air shutoff relay and engine ground.

 

4. Start the engine.

 

5. Activate the overspeed verify switch.

 

6. Monitor the test lamp while you increase the engine speed past 75 percent of the programmed overspeed setpoint.

 

7. Stop the engine.

 

8. Remove the test lamp from the circuit. Restore the wiring to the original configuration.

Expected Result:

The test lamp illuminated when the engine speed increased past 75 percent of the programmed overspeed setpoint.

Results:

 

• OK – The test lamp illuminated. The air shutoff relay is operating correctly. Proceed to Test Step 3.
• Not OK – The test lamp did not illuminate. No voltage is present at the output of the relay. Proceed to Test Step 4.

Test Step 3. Test for Voltage at the Air Shutoff Solenoid

 

1. Remove electrical power from the ECM.

 

2. Disconnect the wire from the positive terminal of the air shutoff solenoid.

 

3. Connect a test lamp between the wire for the positive terminal of the air shutoff relay and engine ground.

 

4. Start the engine.

 

5. Activate the overspeed verify switch.

 

6. Monitor the test lamp while you increase the engine speed past 75 percent of the programmed overspeed setpoint.

 

7. Stop the engine.

Expected Result:

The test lamp illuminated when the engine speed increased past 75 percent of the programmed overspeed setpoint.

Results:

 

• OK – The test lamp illuminated.Repair: The voltage is present at the air shutoff solenoid. Check for continuity of the ground circuit for the air shutoff solenoid before proceeding. If the ground circuit is OK, replace the air shutoff solenoid. Verify that the problem is resolved.STOP
• Not OK – The test lamp did not illuminate.Repair: System voltage was not present at the air shutoff solenoid. There is a problem in the wiring between the output of the air shutoff relay and the input of the air shutoff solenoid. There may be a problem in a connector. Repair the wiring and/or the connector. Replace parts, if necessary. Verify that the problem is resolved.STOP

Test Step 4. Test the Control Input Voltage at the Air Shutoff Relay

 

1. Remove electrical power from the ECM.

 

2. Disconnect the wires from the control input of the air shutoff relay at the relay.

 

3. Connect the test lamp between the two control wires.

 

4. Start the engine.

 

5. Activate the overspeed verify switch.

 

6. Monitor the test lamp while you increase the engine speed past 75 percent of the programmed overspeed setpoint.

 

7. Stop the engine.

Expected Result:

The test lamp illuminated when the engine speed increased past 75 percent of the programmed overspeed setpoint.

Results:

 

• OK – The test lamp illuminated. Control input voltage is reaching the relay. Proceed to Test Step 6.
• Not OK – The test lamp did not illuminate. The voltage from the ECM was not present at the coil of the air shutoff relay. Restore the wiring to the original configuration. Proceed to Test Step 5.