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Home >> Isuzu >> 2008 >> Ascender LS, RWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System & Fuel System - 4.2L - DTC P0366 To DTC P2444 >> DTC P0411 >> Circuit/System Testing
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Circuit/System Testing

IMPORTANT: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
  1. Inspect the AIR solenoid outlet pipe for leaks.
  2. Ignition ON, observe that the AIR pump is not activated.
    • If the AIR pump is activated, test the AIR pump voltage supply circuit for a short to voltage. If the circuit tests normal, test the AIR pump relay control circuit for a short to ground. If the circuits test normal, test the AIR pump relay. If the relay and circuits test normal, replace the ECM.
  3. Ignition ON, enable the AIR pump with a scan tool and observe that the AIR pump is activated.
    • If the AIR pump is not activated, test the AIR pump voltage supply and ground circuits for more than 2 ohms of resistance. If the circuits test normal, test both AIR pump relay voltage supply circuits for an open/high resistance or a short to ground. If the circuits test normal, test the AIR pump relay control circuit for an open/high resistance or a short to voltage. If the circuits test normal, test the AIR pump relay. If the relay and circuits test normal, test the AIR pump. If the relay, pump, and circuits test normal, replace the ECM.
  4. Disconnect the AIR solenoid.
  5. Connect a test lamp between the AIR solenoid voltage supply circuit terminal 6 and ground circuit terminal 4.
  6. Ignition ON, observe that the test lamp is not illuminated.
    • If the test lamp is illuminated, test the AIR solenoid valve voltage supply circuit for a short to voltage. If the circuit tests normal, test the AIR solenoid valve relay control circuit for a short to ground. If the circuits test normal, test the AIR solenoid valve relay. If the relay and circuits test normal, replace the ECM.
  7. Enable the AIR solenoid with a scan tool and observe that the test lamp is illuminated.
    • If the test lamp is not illuminated, test the AIR solenoid voltage supply circuit and both AIR solenoid relay voltage supply circuits for an open/high resistance or a short to ground. If the circuits test normal, test the AIR solenoid ground circuit for an open/high resistance. If the circuits test normal, test both AIR solenoid relay control circuits for and open/high resistance or a short to voltage. If the circuits test normal, test the AIR solenoid relay. If the relay and circuits test normal, replace the ECM.
  8. Connect all electrical connectors.
  9. Engine RUNNING, enable the AIR solenoid valve with a scan tool and observe that the AIR Pressure Sensor parameter equals approximately 8-10 kPa above BARO.
    • If not within the specified range, continue with this procedure.
  10. Remove the AIR inlet hose from the AIR pump.
  11. Engine RUNNING, enable the AIR solenoid valve with a scan tool and observe that the AIR Pressure Sensor parameter increases to 8-10 kPa above BARO.
    • If within the specified range, the AIR pump inlet hoses/pipes are restricted. Remove the restriction or replace the hose/pipe.
    • If not within the specified range, continue with this procedure.
  12. Disconnect the hose from the AIR pump outlet.
  13. Disconnect the hose quick-connect from the AIR solenoid valve inlet.
  14. Install a length of standard 1 inch I.D. (25.4 mm) hose from the AIR pump outlet to the AIR solenoid valve inlet.
  15. Engine RUNNING, enable the AIR solenoid valve with a scan tool and observe that the AIR Pressure Sensor parameter increases to 8-10 kPa above BARO.
    • If within the specified range, the AIR pump outlet hoses/pipes are restricted or leaking. Remove the restriction or replace the hose/pipe.
    • If less than the specified range, replace the AIR pump.
    • If more than the specified range, continue with this procedure.
  16. Remove the AIR solenoid valve.
  17. Leave the standard hose and harness connector connected.
  18. Engine RUNNING, enable the AIR solenoid valve with a scan tool and observe that the AIR Pressure Sensor parameter increases to approximately 7 kPa above BARO.
    • If more than the specified range, replace the AIR solenoid valve.
    • If within the specified range, test/inspect the cylinder head for restriction.
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