GM Service Manual Online
For 1990-2009 cars only
  1. Run water through a hose without the nozzle attached.
  2. Begin testing at the base of the window or windshield.

  3. Object Number: 95572  Size: SH
  4. Slowly move the hose upward and across the top of the window.
  5. Have a second person sit in the vehicle in order to watch for leaks.