Secondary Air Bag Warning
WARNING: This page is about a different car, the 2008 Ford RV Cutaway, 2008 Ford Econoline, 2008 Ford E450 Super Duty, and 2008 Ford Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
The secondary air bag warning is an audible tone that consists of 5 sets of 5 tone bursts, with each set of 5 tone bursts separated by a 5-second quiet period. One tone burst cycle will consist of one-second ON and one-second OFF. The tone pattern will repeat periodically until the problem and warning light are repaired.