[Traylaw]

Need more information, a flashing D is like the check engine light for the transmission. There will be one or more error codes stored in the cpu concerning the transmission. You need to contact your dad's transmission guy and find out what those codes are. We might be able to help with this information.

 

[Traylaw]

Is he taking you for a ride? Maybe or there is some confusion as to the issues. The torque converter is part of the transmission. As previously mentioned it is normally replaced without replacing the entire transmission. The throttle body is part of the engine which controls the amount of air going into the engine's air intake. When you step on the gas you are opening up the throttle body to allow more air into the engine. The throttle body and torque converter are two unrelated parts of the car.

The flashing D is letting you know there is a problem with the transmission and there is a pending error code describing the issue. So there is definitely and issue there.

As to the throttle body, maybe your dad's mechanic also saw something else going on. But you normally don't replace the entire throttle body. You might replace the electric actuator module on the throttle which is what opens/closes the air valve (aka throttle plate) when you press and release the gas pedal.

I would at least get a second opinion here and ask lots of questions. Good mechanics have no problem answering questions and explaining why they believe something is wrong. Bad mechanic tend to get irritated when confronted with questions.