Ford 1998 Windstar Owner's Manual page 15

If the driver fastens the safety belt before the ignition is
turned to ON, the chime will not sound and the light will
not illuminate.
If the safety belt is buckled while the light is on and the
chime is sounding, both the light and the chime turn off.
The safety belt warning light
Service Engine Soon Warning Light
This light illuminates when the engine's Emission Control
System requires service. It will also illuminate when the ignition
key is in the ON position and the engine is off.
The service engine soon warning light
Modifications or additions to the vehicle may cause incorrect
operation of the OBD II system. Additions such as burglar
alarms, cellular phones, and CB radios must be carefully
installed. Do not install these devices by tapping into or running
wires close to powertrain control system wires or components.
Instrumentation
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