GM Service Manual Online
For 1990-2009 cars only
  1. Clean away any dirt that is around the reservoir cap.
  2. Remove the cap.
  3. Inspect the fluid level.
  4. The fluid level should be even with the bottom of the filler neck when the brake is applied.
  5. Add Dexron® III transmission fluid if the fluid is low.
  6. Install the cap.