It looks like the issue is the switch itself. Overdrive on/off light is only controlled by this switch. So if it is coming on and staying on or flashing there maybe an issue with the transmission. Refer to your owner manual for more information on the overdrive switch.
It's possible that a cleaning solution sprayed onto the switch could causing erractic operation of the O/D switch. Have you tried to press the button harder than usual to switch off over drive?
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Monday, January 13th, 2014 AT 9:29 PM