How many of you out there know what a TCU is? How about if I asked about the transmission Control Unit? Now how many hands do we have?
The Transmission Control Unit is a device that controls modern electronic automatic transmissions. It is really the brains of the modern automatic transmission. It gets its information from sensors inside the engine and also from data provided by the engine control unit (ECU), and uses that information to calculate how and when to change gears for optimum performance, fuel economy and shift quality.
This is not new technology. The TCU has been in development since the late 1980s and transmission manufacturers have been slowly moving away from hydromechanical controls to electronic controls.
A modern TCU is made up of the following components:
- Vehicle speed sensor which determines the current speed of the vehicle
- Wheel speed sensor which measures the true speed of the vehicle and also determines whether it is going uphill or downhill.
- Throttle position sensor determines engine load and optimum time and characteristics for a gear change.
- Turbine speed sensor measures the rotational speed of the input shaft or torque converter.
- Transmission fluid temperature sensor, the purpose of which is obvious, but it is used to determine if the transmission is running too hot and if downshifting is needed.
- Kick down switch determines if the accelerator pedal has been depressed past full throttle.
- Brake light switch determines whether to activate the shift lock solenoid to keep the driver from shifting without a foot on the brake.
- Traction control system which detects unfavorable road conditions.
- Cruise control module takes into account the fact that the driver is not using the throttle.
- Shift lock prevents shifting without the brake pedal being depressed.
- Shift solenoids are activated to change gears.
- Pressure control solenoids control the amount of hydraulic pressure used for shifting.
- Torque converter clutch solenoid regulates the torque converter electronically.
It should be obvious even to a novice that the TCU is crucial to the proper performance of a modern automatic transmission, and only a professional should be working on one, and that brings us to PDQ transmission parts, a place operated by nothing but professionals in the field of automatic transmissions.
For something as important as your vehicle’s transmission, who are you going to trust? PDQ Transmission Parts is the trusted leaders in the transmission world.
