The overdrive solenoid is malfunctioning.
The overdrive solenoid is a small electrical component that is responsible for engaging and disengaging the overdrive gear. If the solenoid is malfunctioning, it can cause the overdrive light to blink.
The overdrive switch is malfunctioning.
Another potential cause of a blinking overdrive light is a malfunctioning overdrive switch. The overdrive switch is the button that you press to turn the overdrive on and off. If the switch is malfunctioning, it can cause the overdrive light to blink.
There is a problem with the transmission.
The overdrive light can also blink if there is a problem with the transmission. Some common transmission problems that can cause the overdrive light to blink include low fluid levels, worn gears, and leaks.