over drive light blinking on 1998 Ford Mustang

I drive the car once it goes through one shift sequence the over drive light starts blinking and does not stop until i turn off the car when it is shifting (automatic) it shifts very hard I have checked the transmission fluid level and it seems perfect.

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1 answer
it sounds like something has gone wrong and your transmission has gone into default mode
is it shifting hard? and at a slightly higher rpm?