Plain and simple the overdrive switch is pmost definitely bad take to a professional if you don't know what your doing,go to a shop that specializes in electrical work NOT THE DEALER,they will tell...
It makes the car have that "extra gear" which allows you to cruise the roads with a 4th gear rather than have only 3 gears without overdrive THERE IS A BUTTON ON THE SHIFTER, UNDER THE "t" HANDLE....
Located on the carb look at your throttle linkage. Under the throttle linkage but on the same plate you will see another rod that runs down behind the engine. This rod also is used for your passing...