Originally, automatic transmissions were controlled solely by hydraulic pressure. But modern transmissions benefit from the transmission control module, which is a computer that works in tandem with the engine control unit/ECU. By using data provided by a bevy of sensors, the TCU can execute shift strategies that maximize both performance and economy. So let’s take a closer look and answer the question; what is a transmission control module?
What Transmission Do I Have?
What is the transmission control module?
The TCM, or transmission control module is a computer that uses input from sensors around the vehicle to perform a number of different tasks related to the transmission. It’s in constant communication with the ECU, or engine control unit to ensure that each gear change is appropriate to what the engine is doing. This little brain box is typically located on or near the transmission. However in some cases, it can be located inside of the transmission.
Different auto manufacturers call the TCM other things. Like for example; Toyota calls it the powertrain control module, GM refers to it as the transmission controller, and other manufacturers call it the transmission control unit/TCU.
Some manufacturers like General Motors and Mercedes combine the TCM with other components such as valve body solenoids, temperature switches, and speed sensors to create a single unit that is installed inside of the transmission. The General Motors TEHCM and Mercedes conductor plate can be prone to failure due to their complex design. If you are having problems with these and would like more information on the benefits of installing a remanufactured GM TEHCM or remanufactured Mercedes conductor plate, click the appropriate link below.
Remanufactured 6L80 & 6L90 TEHCM
Remanufactured 722.9 Mercedes Conductor Plate
What does a transmission control module do?
One of the main jobs of the transmission control module is to control shift timing by activating the appropriate shift solenoids, which then actuate a gear change. In order to do this, the TCM has to process data from a number of sensors, including the throttle position sensor/TPS, the vehicle speed sensor/VSS, the wheel speed sensors/WSS, the kick down switch, the turbine speed sensor/TSS, the transmission fluid temperature sensor/TFT, the traction and stability control systems, and even the cruise control module and brake light switch. Adding all of this data together allows the transmission control module to create a shift program that is appropriate for the way the vehicle is being driven.
What Transmission Do I Have?
Symptoms of a failed transmission control module
If your transmission control module is failing, you’ll notice a significant reduction in vehicle/transmission performance. The transmission may hesitate to shift, completely refuse to shift or even go into gear. If you are experiencing problems with your TCM and would like more information on the benefits of a remanufactured transmission control module, click here.
