Yes, the transmission control unit (TCU) will need to be reprogrammed after removing and reinstalling the transmission on a 2006 Sienna. The TCU stores information about the transmission's gear ratios and shift points, and this information must be reprogrammed after the transmission has been removed and reinstalled in order for the transmission to function properly.
The TCU can be reprogrammed using a diagnostic tool that is compatible with the Sienna's CANBUS system. The diagnostic tool will be used to access the TCU and input the necessary information about the transmission's gear ratios and shift points.
