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Home >> Buick >> 2015 >> Verano Leather >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 6 (Engine Controls And Fuel - 2.0L (LHU) - DTC P025A To DTC P2635 Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P2261: Turbocharger Bypass Valve Stuck >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
  1. Verify the conditions listed below do not exist:
    • Vacuum leaks
    • Vacuum line restrictions
    • Improper routing or connecting of the vacuum hoses on the turbocharger bypass valve solenoid, the bypass valve, and the bypass valve vacuum tank
    • If a condition is found, repair or replace the affected component as necessary.
  2. Ignition OFF, disconnect the vacuum supply hose from the Q40 turbocharger bypass solenoid valve and connect the J-23738-A  or a suitable vacuum gauge to the hose.
    3. NOTE:
    • Engine temperature, accessory load, and elevation level will affect engine vacuum.
    • Vacuum readings will decrease by approximately 2.7 kPa (0.8 in Hg) for every 305 m (1, 000 ft) of elevation above sea level.
  3. Engine Idling, the gauge should read between 47-68 kPa (14-20 in Hg).
    • If not within the specified range, inspect and repair the vacuum source or the vacuum leak in the areas listed below:
    • The vacuum hose between the Q40 turbocharger bypass solenoid valve and the turbocharger bypass valve vacuum tank
    • The turbocharger bypass valve vacuum tank
    • The vacuum hose between the turbocharger bypass valve vacuum tank and the intake manifold
  4. Ignition OFF, disconnect the J-23738-A  or vacuum gauge and reconnect the hose to the Q40 turbocharger bypass solenoid valve
  5. Disconnect the vacuum hose from the turbocharger bypass valve and connect the J-23738-A  or a suitable vacuum gauge to the hose.
  6. Engine Idling, command the turbocharger bypass solenoid valve between Active and Inactive with a scan tool while observing the vacuum gauge. The gauge should read between 47-68 kPa (14-20 in Hg) when commanded Active and 0 kPa (0 in Hg) when commanded Inactive.
    • If not within the specified range, inspect the vacuum hose for a leak or restriction. If a condition is found, replace the hose. If a condition is not found, replace the Q40 turbocharger bypass solenoid valve.
  7. Ignition OFF, inspect the turbocharger bypass valve assembly for damage. Refer to Turbocharger Cleaning and Inspection (LDK, LHU) .
  8. Disconnect the vacuum hose that runs from the turbocharger bypass valve vacuum tank to the Q40 turbocharger bypass solenoid valve at the tank.
  9. Connect the J-23738-A  to the turbocharger bypass valve vacuum tank.
  10. Apply 51 kPa (15 inches Hg) of vacuum to the tank. Verify the tank maintains vacuum without decay.
    • If the tank does not maintain vacuum, replace the turbocharger bypass valve vacuum tank.
  11. If all components test normal, replace the charge air bypass valve.
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