99 f250 blinking overdrive switch?
Do you mean automatic signal cancel?
Check the switch on the end of your shift lever; it may be loose. Try turning it on/off a couple times. (My next step requires interaction between your wallet and a dealer))
Overdrive is the normally allowed position It won't shift into overdrive until the speed is higher anyway ( such as the highway / freeway ) If you are towing something or if you are driving in hilly country where the transmission is constantly shifting between overdrive and drive , then you want to shut the overdrive off using the switch on the end of your gear selector lever ( P R N etcetera , O/D…