Transmission Control Module: Notes

WARNING: This page is about a different car, the 2018 Jaguar XE and 2017 Jaguar XE. However, it is still accessible from the selected car via links, so may be relevant.

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

The TCM processes signals from the following:

Transmission speed sensors
Transmission temperature sensors
Transmission Control Switch (TCS)
Powertrain Control Module (PCM)
other vehicle systems.

The PCM supplies the engine management data over the FlexRay systems bus. The TCM requires engine data to efficiently control the transmission operation, for example drive plate torque, engine speed, accelerator pedal angle, engine temperature. The steering angle sensor and the Anti-lock Brake System (ABS) control module also supply data to the TCM on the FlexRay systems bus. The TCM uses data from these systems to suspend gear changes when the vehicle is cornering and/or the ABS control module is controlling braking or traction control.

The paddle switches are hardwired to the right steering wheel switchpack. Operation of the paddle switch completes a ground path to the switchpack. The switchpack converts the completed ground signal into a Local Interconnect Network (LIN) bus signal which is passed via the Clockspring (CLKSPG) and the Steering Wheel Module (SWM) to the Body Control Module/Gateway Module (BCM/GWM) assembly. The BCM/GWM converts the signal into a FlexRay bus signal to the Transmission Control Module (TCM).

Using the signal inputs and the pre-programmed data, the TCM control program calculates the correct gear and torque converter lockup clutch setting. The optimum pressure settings for gear shift and lock-up clutch control are also controlled by the TCM. Special output-side modules (power output stages, current regulator circuits), allow the TCM to control the solenoid valves and pressure regulators and consequently precisely control the hydraulics of the automatic transmission. In addition, the amount and duration of engine interventions are supplied to the engine management by way of the FlexRay systems bus.