Over drive light flases on and off..what is the cause? on 2002 Ford Escape

Have a problem with overdrive flashing on and off. this has occurred for awhile now. Once you shut ignition off and restart, it doesnt flash until driving for awhile. 2 days ago it stopped pulling in drive. but works in low 2 and low 1 and reverse. what could be the problem. have been told could be coil packs in transmission..

Asked by for the 2002 Ford Escape
the flashing indicates trans issues. i rec you get a free diag at aamco but shop there findings
1 more answer
Its a malfuntion being detected most likely. Transmission sets fault codes simular to engine. could be detecting slippage or over heat condition etc.