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 valves.
  3. The pressure relief valves are located in the door (coupe) or rear door (sedan) openings.

  4. Close any vehicle openings, such as the doors and the windows.
  5. Pressurize the vehicle interior.
  6. Turn on the vehicles 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.