Overdrive is like 5th gear for cruising in most automatic transmissions, the common place for the on and off button is on the gear selector.
overdrive shut off
Light being on means overdrive is inactive
If the overdrive's off light is on that means it's off. If it is off then the overdrive is on.
When the overdrive light blinks that means a malfunction has been detected - get it checked out
OD means Overdrive. The light is on because you have disengaged the Overdrive. The button is on the shift lever on the side. Push that button to engage the overdrive.
it means the overdrive is not on.
There is a problem with the transmission.
That means you are either in overdrive or you have a defect in the dash lights that is turning on your overdrive light. Wiki can explain what overdrive is better than I can, but it's not a bad thing. You should probably just leave your vehicle in overdrive for better fuel economy.
If the light says off then your overdrive is turned off, push the button again and the light will turn off and overdrive will be on again.
It's informing you that the overdrive button (which is located on the side of the gearshift) has been switched off...just press it to turn it back on, which would be more economical.
Problem with the Overdrive system or the Transmission.
The overdrive off light will flash in your gauge cluster when a malfunction has been detected by the powertrain control module