Transmission Control Module (TCM)

WARNING: This page is about a different car, the 2018 Land Rover Discovery Sport. However, it is still accessible from the selected car via links, so may be relevant.

The TCM is located on the top of the automatic transmission casing and is connected on the high speed CAN powertrain systems bus to send and receive information to and from other system modules.

The TCM outputs signals to operate the transmission solenoid valves to control the hydraulic operation of the transmission.

The ECM (engine control module) supplies the engine management data on the high speed CAN powertrain systems bus. The TCM requires engine data to efficiently control the automatic transmission operation, using for example; crankshaft torque, engine speed, accelerator pedal angle, engine temperature etc.

The TCM processes signals from the transmission speed and temperature sensors, ECM and other vehicle systems. From the received signal inputs and pre-programmed data, the TCM calculates the correct gear, torque converter clutch setting and optimum settings for gear shift and lock-up clutch control.

The steering angle sensor and the ABS (anti-lock brake system) module also supply data to the TCM on the high speed CAN powertrain systems bus. The TCM uses data from these systems to suspend gear changes when the vehicle is cornering and/or the ABS module is controlling braking or traction control.

The transmission is controlled by a 'shift by wire' system. The TCS is connected to the TCM on the high speed CAN powertrain systems bus. Driver selections made on the TCS are passed via CAN messages to the TCM.

If the TCM, the transmission or the valve block is replaced, a diagnostic routine using an approved Land Rover diagnostic system will be required to calibrate the TCM to learn the Touchpoint Adaptions. Refer to 'Touchpoint Adaptions' and 'Clutch Adaptions' later in this article.