Every so often my overdrive light on the end of my shifter blinks saying that overdrive is off, and does not stop no matter how much you hit the button regardless of whether overdrive is on or off.

 

First make sure that your tranny fluid level is where it needs to be, thenconsult the manual to see if it gives you an indication of what could be wrong, and finally see if you have your coades read to see if the computer is giving any codes that may point you in the right direction. You can have this done for free at a place like Auto Zone.