Q: Transmission not shifting into overdrive

Hello. If the transmission is shifting fine but will not go into overdrive, then it may have a solenoid failure or a pressure problem. A bad brake light switch can also cause this. I would typically start by checking to see if the brake light works. If they don’t or if they remain on, then I would replace the switch. If any of the previous issues mentioned are no the cause, then the transmission would need to be diagnosed. I would get some help from a certified mechanic, like one from yourMechanic, toreplace the brake light switchand inspect any other possible issues.