CM850 Electronic Control System – Air Shutoff Valve will not Deactivate

Symptom Tree  t165

This is symptom tree t165
Cause Correction

Active air shutoff valve fault code(s)

Troubleshoot any active air shutoff valve fault codes first.


Air shutoff lamp stays illuminated

Troubleshoot the air shutoff lamp circuit. Verify the proximity switch operation. The switch is normally open. The circuit is closed when the valve is in the closed position.


Turn the keyswitch OFF and back ON

Verify the air shutoff valve has reset by checking the solenoid shaft position. Attempt to start the engine.


Use INSITE™ electronic service tool to verify the engine rpm reading is zero

Connect INSITE™ electronic service tool and open the data monitor/logger. Monitor the rpm parameter. Verify the ECM rpm reading is zero with the engine off.


Verify the shutoff solenoid resistance

Disconnect the air shutoff valve from the engine harness and check the resistance of the air shutoff valve solenoid. The resistance should be between 15 and 25 ohms. Replace the air shutoff solenoid if not within specification.


Verify the diagnostic voltage from the OEM connector at the air shutoff solenoid

Disconnect the air shutoff solenoid from the engine harness. Verify the diagnostic voltage from the signal pin is 0-VDC.


Verify the diagnostic voltage from the ECM connector

Disconnect the OEM harness from the ECM and verify the diagnostic voltage. Replace the ECM if 5-VDC is present. Refer to Procedure 019-031 in Section 19. If 5-VDC is not present, troubleshoot the OEM harness. Refer to Procedure 019-043 in Section 19.

Last Modified:  03-Mar-2010