Transmission control module is a device that manages automatic transmissions. A TCM usually monitors sensors from the vehicle as well as information given by the engine control unit, to regulate how and when to alternate gears in the vehicle for best perforfmance.
The sensors that TCM reads are: Vehicle Speed Sensor (VSS), Wheel Speed Sensor (WSS), Throtle position sensor(TPS), Turbine input speed sensor (TSS), transmission fluid temperature sensor (TFT), traction control system (TCS), Kick Down Switch, Brake Light Switch, Cruise Control Module (CCM), Inputs from Other Controllers; such as Chrysler CCD bus, etc.
TCM takes all those input, processes them, and as a result it is able to shift gears, up and down as a requirment of the vehicle and driver.
The main component of making those difficult descisions of the up-shifting and down-shifting, is a software inside a microprossesor. It has to take more than a thousand descision per second. We can say the Transmission Control Module is as equally sophisticated as to compete with a robot.
The faliures on those kinds of modules are related with software, hardware. And as we explain on ECM,the faliure could be Present All the time or Intermitent Random. If it happens to be Intermitent Random faliures these are more difficult to diagnose, because if the first signs of faliure occurs now, the next one is a mystery becasue it could show at any time , seconds, minutes, days, weeks, or even in extreme cases months.
