See also:

Safety belt warning light and indicator chime
The safety belt warning light illuminates in the instrument cluster and a chime sounds to remind the occupants to fasten their safety belts. ...

Second generation (2003–2006)
The Navigator was updated in 2003, along with the Ford Expedition, on the new Ford U platform. The interior was also substantially revised to bring it up to the level expected by luxury buyers. So ...

Determining if the system is operational
The supplemental restraint system uses a warning indicator light in the instrument cluster or a backup tone to indicate the condition of the system. Refer to the Warning lights and chimes section ...