Ford 1996 Windstar Manual page 88

Check Engine Warning Light
The Powertrain On-Board Diagnostic II (OBD II) system consists
of the hardware and software necessary to monitor the
operation of the powetrain. The OBD II system is designed to
check the function of the vehicle's powertrain control system
during normal operation. If an emission problem is detected, the
Check Engine Warning Light (in the cluster) is turned on.
The check engine warning light
Modification 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.
The light comes on briefly when you turn the ignition key to
ON, but it should turn off when the engine starts. If the light
does not come on when you turn the ignition to ON or if it
comes on and stays on when you are driving, have your vehicle
serviced as soon as possible. This indicates a possible problem
with one of the vehicle's emission control systems. You do not
need to have your vehicle towed in.
If the light turns on and off at one (1) second intervals while
you are driving the vehicle, it means that the engine is
misfiring. If this condition persists, damage could occur to the
engine or catalytic convertor. Have your vehicle serviced at the
first opportunity. You do not need to have your vehicle towed
in.
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