Transmission Control Module

The Transmission Control Module (TCM) outputs signals to control the hydraulic operation of the transmission. The signals are sent to the shift control solenoid valves and the Electronic Pressure Regulating Solenoids (EPRSs).

The TCM processes signals from the transmission speed and temperature sensors, the Transmission Control Switch (TCS), the Powertrain Control Module (PCM) and other vehicle systems. From the received signal inputs and pre-programmed data, the TCM calculates the:

• Correct gear.
• Torque converter clutch setting.
• Optimum pressure settings for gear shift and lock-up clutch control.

The PCM supplies the engine management data over the FlexRay. The TCM requires engine data to efficiently control the transmission operation, for example:

• Flywheel torque
• Accelerator pedal angle
• Engine temperature.

The steering angle sensor and the Anti-lock Brake System (ABS) control module also supply signal to the TCM. The signal is transmitted to the TCM through the Body Control Module/Gateway Module (BCM/GWM) and the Transfer Case Control Module (TCCM) on the FlexRay. The TCM uses the signals to suspend gear changes when the vehicle is cornering and/or the ABS control module is controlling braking or traction control.

The Body Control Module/Gateway Module (BCM/GWM) supplies paddle switches data to the TCM on the High Speed (HS) Controller Area Network (CAN) powertrain systems bus. The TCM uses the signals to schedule driver requested upshifts and downshifts.

The TCM control program computes the correct gear and disconnect and launch clutch settings by using the signal inputs and the memorized data. The TCM also computes the optimum pressure settings for gear shift and clutch control. Special output side modules (power output stages, current regulator circuits), allow the TCM to control the solenoid valves and pressure regulators. This allows the TCM to precisely control the hydraulics of the automatic transmission. In addition, the amount and duration of engine interventions are supplied to the PCM through the FlexRay.

The TCM determines the position of the TCS using signals from the TCS on the HS CAN powertrain systems bus.

The TCM transmits the position of the TCS and any manual gear selected on the FlexRay to the Transfer Case Control Module (TCCM). Then the TCCM transmits the information to the Body Control Module/Gateway Module (BCM/GWM) through the FlexRay. The information is shown in the gear selector display in the Instrument Cluster (IC) from the BCM/GWM.