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Home >> GMC >> 2018 >> Acadia Denali, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 135 (Engine Controls And Fuel - 3.6L (LF4 LGX) - DTC P0010 To DTC P0121 LGX) >> Diagnostic Information and Procedures >> DTC P00C4 or P2261: Turbocharger Bypass Valve Stuck >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2016 Cadillac ATS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Verify the conditions listed below do not exist:
    • Vacuum leaks
    • Vacuum line restrictions
    • Improper routing or connecting of the vacuum hoses on the Q40 Bypass Solenoid Valves, bypass valves, Q42 Turbocharger Wastegate solenoid valves, wastegate valve actuators, vacuum pump and the vacuum tank.
    • If a condition exists 

      Repair or replace the component as necessary.

    • If none of the conditions exist 
  2. Ignition Off, disconnect the vacuum supply hose at the turbocharger vacuum pump.
  3. Connect the GE 23738-A  to the pump outlet.
    4. NOTE:

    To determine the vacuum value, subtract the absolute value of the vacuum gauge reading from the barometric pressure.

  4. Engine Idling, verify the vacuum value is less than or equal to 15 kPa (4.4 inches Hg).
    • If not within the specified range 

      Repair or replace the vacuum pump.

    • If within the specified range 
  5. Ignition Off, disconnect all vacuum hoses at the appropriate turbocharger vacuum tank and cap or plug the valve outlet ports.
  6. Connect the GE 23738-A  to the vacuum tank inlet port and apply 5 kPa (1.5 inches Hg) of vacuum.
  7. Verify the tank holds vacuum for at least 10 s.
    • If the vacuum is not held for at least 10 s 

      Replace the vacuum tank.

    • If the vacuum is held for at least 10 s 
  8. Connect the vacuum hoses to the tank.
  9. Disconnect the Q40 Turbocharger Bypass Solenoid Valve output to mechanical bypass valve input vacuum hose at the bypass valve and connect the GE 23738-A  to the hose.
  10. Engine idling.
    11. NOTE:

    To determine the vacuum value, subtract the vacuum gauge reading from the barometric pressure.

  11. Verify the vacuum value toggles between 0 kPa (0 inches Hg) to less than or equal to 15 kPa (4.4 inches Hg), when commanding the Turbocharger Bypass Solenoid Valve between Active and Inactive with a scan tool.
    • If not within the specified range 

      Replace the Q40 Turbocharger Bypass Solenoid Valve.

    • If within the specified range 
  12. Connect any hoses that were disconnected during previous steps.
  13. Verify the conditions listed below do not exist with the mechanical turbocharger bypass valve assembly:
    • Damage
    • Leaks
    • Restrictions
    • If a condition exists 

      Repair or replace the mechanical turbocharger bypass valve as necessary.

    • If none of the conditions exist 
  14. Replace the B111B Turbocharger Boost/Intake Air Temperature Sensor.
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