Safety Belt Warning Chime
WARNING: This page is about a different car, the 2004 Mercury Monterey and 2004 Ford Freestar. However, it is still accessible from the selected car via links, so may be relevant.
The safety belt warning chime is activated when the ignition switch is in the RUN position and the restraint control module (RCM) detects an unbuckled driver or front passenger safety belt. The instrument cluster generates the chime. The duration of the chime is 6 seconds or until the safety belt is buckled.