You just sold a shop a remanufactured transmission, and now they are saying it's not working. After installing it in the vehicle, what questions should you ask before they remove the transmission for a return? Simple. Did you program the transmission control module? Most remanufactured transmissions do not come. This is because the remanufacturer does not know the vehicle the transmission is going into. Most transmissions require that the control module is programmed on the vehicle. Some shops may not realize they need to perform this critical last step. A modern transmission is connected to multiple modules on the vehicle. It communicates with the engine and the a BS on the high speed network. The protocols or language of the network uses OEM and vehicle specific data like the VIN and vehicle configuration for options. This data or firmware is written specifically for the vehicle by the OEM. Another task programming the transmission does is clearing existing adaptations for the old transmission.