Gearbox is not shifting properly and the D light is blinking?

Hello, I'm Danny.

Having the transmission "D" indicator light flashing means there is a transmission fault code or codes stored in your vehicles computer that can be causing this issue. The best thing to do is perform a CAN scan- controller area network that will check any transmission codes as well as other systems on your vehicle. Here is a tutorial showing how to perform a CAN scan:

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

After performing this CAN scan get back to us with any code information on the transmission or other systems and we can the properly diagnose the issue on your car. Hope this helps and thanks for using 2CarPros.