Electronically Controlled Transmission (ECT)

On Camry 4-Cylinder and Supra with separate control unit for the ECT, the engine ECU will transmit a signal to the transmission control unit to control overdrive engagement. The ECU uses input from the coolant temperature sensor to prevent a shift into overdrive when the engine is cold.

All other models do not have a separate control unit for the transmission, all shift functions are controlled by the engine ECU.