GM Service Manual Online
For 1990-2009 cars only
  1. Perform a visual inspection. Refer to Air/Wind Noise .
  2. Mask off the body pressure relief valve.
  3. The pressure relief valve is accessed from inside the vehicle by repositioning the rear compartment trim panel.

  4. Close any vehicle openings, such as the doors and the windows.
  5. Pressurize the vehicle interior.
  6. Turn on the ventilation fan or pressurize the vehicle interior with an air hose.

    Specification
    Pressurization (maximum): 105 kPa (30 psi)

  7. Apply a soapy solution to any potential leak areas on the outside of the vehicle.
  8. Watch for bubbles at the areas where the soapy solution was applied.