GM Service Manual Online
For 1990-2009 cars only

The roof mast antenna can fold down. Fold the antenna by pushing the antenna at the hinge making the antenna flat against the roof. Fold the antenna when going through car washes to avoid damage.

You may experience poor reception when the antenna is folded flat. To eliminate this problem, make sure that the antenna is in its upright position.

Check occasionally to be sure the mast is still tightened to the roof mount. If tightening is required, tighten it by hand.