General Descriptions

The AW 50-42 is an electronically-controlled four-speed automatic transmission with torque converter lock-up of the three highest gears. Because the transmission is controlled by an electronic control module gear-shifting can be controlled to allow the correct gear to be selected for driving conditions, engine load, driver's wishes, speed, etc. This yields good fuel economy combined with top-class performance and increased comfort by ensuring smoother shifts and lower noise levels.

A control module receives information about the selected gear and driving mode setting required. Together with signals from a number of sensors describing the running conditions of the car, this information is processed by the control module, which calculates optimum shifting and lock-up engagement points, depending on the driving mode selected. The control module then controls shifting and lock-up engagement by acting on the transmission hydraulic system. The control module also affects the quality of gear-changing by instantaneously modifying the hydraulic line pressure when shift is made.

The transmission's electronic control system receives continuous information from a number of sensors, as well as from the engine control system. Unlike a transmission with just a hydraulic control system, this enables the control system to adapt to extremely small changes in operating conditions and to control the various transmission functions so that the correct gear is always selected in accordance with the driving mode selected by the driver.

To facilitate fault-tracing, the control module has a button on-board diagnostic system (OBD 11 system) which records any faults in the control system and transmission, these can be read off via the Data Link Connector (DLC).