Transmission control unit (TCU) is the core component of automatic transmission control. Is the carrier of control logic, used to process various sensor signals, drive the actuator action, thus forming a control closed loop..Like other vehicle controllers, the TCU typically has two microprocessors, one for computing control logic and the other for troubleshooting and processing. The two microprocessors exchange information with each other via the internal bus.. In addition to the microprocessor, TCU also includes power management module, sensor signal input module, solenoid valve driver module, various indicator light interface and CAN bus communication interface.