You are asking that normally if u press o/d off button on gear shift selector, it does nothing means no o/d off light in the odo meter. Its seems weird because didn't happened for once in all these 4-5 years of my vitz ownership period. I doubt if your gear shifting is smooth or jerky. If it is jerky (i.e. you feel jerk while gear is being shifted) then you will need to replace the gear shifter sensor, it is located on the gear opposite to radiator fan.
