This document describes the structure and working principle of BMW automatic transmission, maintenance and repair contents
This document serves as a technical training manual for BMW automatic transmissions. It covers fundamental concepts such as the comparison between standard and automatic transmissions, the evolution from hydraulic to electro-hydraulic control systems (EGS/TCM), and the basic operation of planetary gear sets and torque converters. The manual is designed to help technicians understand transmission advantages, identification codes, and basic power flow.
| Control System Acronym | EGS |
|---|---|
| Control System Full Name | Electronic Transmission Control |
| Control Module Name | TCM |
| Fluid Function | Lubricates mechanical components |
| Fluid Function | Removes heat |
| Fluid Function | Provides a transfer of kinetic energy |
| Impeller Connection | Rigidly connected to torque converter housing |
| Turbine Connection | Splined to the input shaft |
The acronym EGS is used by BMW for its electronic transmission control system.
EGS stands for "Electronic Transmission Control" which comes from the German words "Elektronisch Getriebe Steurung".
In order to comply with SAE terminology we will refer to the EGS control module as the TCM "Transmission Control Module".
An excessively high fluid level can cause the rotating mechanical components to paddle in the oil, producing foam which introduces air into the hydraulic system.