Transmission problem. Take it to a professional.
Pressing it will disable the overdrive.
The Overdrive Light flashing indicates an internal transmission problem which could be caused by anthiny inside the transmission. Most likely the transmission would have to be removed and taken apart to find the problem.
The overdrive is "ON" when the light is "OFF". Notice the light for the overdrive has a slash through it.
Bad ignition coil
The overdrive in the Windstar could have an internal problem, or the control from the overdrive button may not work. Run a check of computer codes to see if a problem shows up.
The light will flash if the vehicle senses that you should be in overdrive (based on speed) but aren't. There should be a button on the end of your gearshift lever to turn overdrive back on. The only time you should turn that off is, for example, if you are pulling a trailer in the mountains. Turn OD back on and the light will stop flashing. If it doesn't stop then there is a problem with the transmission going into overdrive.
The overdrive ON / OFF switch is located on the end of your gearshift lever ( P R N etc. )
On a 1999 Ford Windstar : The warning light that looks like the shape of an engine is the " check engine " warning light . That means that something has been detected that is effecting the emissions of the vehicle The one that shows " O/D OFF " means that the overdrive has been switched off or if it is flashing that means that a problem has been detected
Easier to say when NOT to use overdrive - which is basically when pulling heavy loads and traveling in very hilly / mountainous areas.
green light whit key flashing and not star
there is a button on the end of th gear shift that you simply push in..
default is of course 'on', does your overdrive switch not work? Overdrive should be saving on gas mileage...To change, you would likely need some way to access the cars computer. Goodluck with that.