Ford Mercury Villager 1997 Owner's Manual page 153

Inflated passenger side air bag
Determining If System Is Operational
The Air Bag Supplemental Restraint System uses a readiness light
to indicate the condition of the system. The readiness light is in
the instrument cluster. When you turn the ignition key to ON, this
light will illuminate for approximately six (6) seconds and then
turn off. This indicates that the system is operating normally.
NOTE: Routine maintenance of the air bag system is not
required.
A problem with the system is indicated by one or more of the
following:
the readiness light will either flash or stay lit,
the readiness light will not light immediately after ignition is
turned on.
Seating and Safety Restraints
149