RENR5042-02 97 Troubleshooting Section Results: C. Connect a test lamp between the wire from the normally open contact of the air shutoff relay and engine ground. OK – The connectors and wiring are OK. Proceed to Test Step 2. D. Start the engine. Not OK The connectors and/or wiring are not OK. E. Activate the overspeed verify switch. Repair: Repair the wiring and/or the connectors. Replace parts, if necessary. Ensure that all of the seals are properly connected. Verify that the problem is resolved. F. Monitor the test lamp while you increase the engine speed past 75 percent of the programmed overspeed setpoint. STOP. Expected Result: Test Step 2.
Test for Voltage from the Normally Open Contacts of the Air Shutoff Relay The test lamp illuminated when the engine speed increased past 75 percent of the programmed overspeed setpoint. A. Turn the keyswitch to the OFF position. Results: OK The test lamp illuminated. The voltage is present at the air shutoff solenoid. B. Remove the wire from the normally open contacts of the air shutoff relay that goes to the air shutoff solenoid. Repair: Verify the continuity of the wire from the air shutoff solenoid to the negative battery before proceeding. Replace the air shutoff solenoid. Verify that the problem is resolved. C.
Connect a test lamp between the normally open contact of the air shutoff relay and engine ground. D. Start the engine. STOP. Not OK – The test lamp did not illuminate. System voltage was not present at the air shutoff solenoid. There is a problem in the wiring between the air shutoff solenoid and the air shutoff relay. There may be a problem with a connector. E. Activate the overspeed verify switch. F. Monitor the test lamp while you increase the engine speed past 75 percent of the programmed overspeed setpoint. G. Turn the keyswitch to the OFF position. Repair: Repair the wiring and/or the connector. Replace parts, if necessary. Verify that the problem is resolved. H.
Disconnect the test lamp’s leads. Connect the wire to the normally open contact. STOP. Expected Result: Test Step 4. Test for Voltage at the Coil of the Air Shutoff Relay The test lamp illuminated when the engine speed increased past 75 percent of the programmed overspeed setpoint. A. Turn the keyswitch to the OFF position. Results: B. Disconnect the wire that carries the drive signal from the ECM to the air shutoff relay. Disconnect the wire at the coil of the air shutoff relay. OK The test lamp illuminated. The air shutoff relay is operating correctly. Proceed to Test Step 3. C. Connect the test lamp between the end of the wire and engine ground. Not OK – The test lamp did not illuminate.
Proceed to Test Step 4. Test Step 3. Test for Voltage at the Air Shutoff Solenoid D. Start the engine. E. Activate the overspeed verify switch. A. Turn the keyswitch to the OFF position. F. Monitor the test lamp while you increase the engine speed past 75 percent of the programmed overspeed setpoint. B. Disconnect the wires that are connected to the coil of the air shutoff solenoid.