Automatic Transmission/Transaxle: Description and Operation

Notes on the automatic 6-speed transmission 09L, 09L, 6 Spd. A/T AWD

Transmission
The 6-speed automatic transmission 09L (all wheel drive) has six hydraulically activated forward gears. When the lock-up clutch is closed these forward gears become mechanically driven gears by cutting out the torque converter slip.

Torque converter
The torque converter is equipped with a slip-controlled lock-up clutch.

Mechatronics unit
The mechatronics unit incorporates the hydraulic control system, the electronic Transmission Control Module (TCM) J217, the Multi-Function Transmission Range (TR) switch F125 and the sensors and actuators as a complete unit. The mechatronics unit is installed in the transmission within the oil pan.

Transmission Control Module (TCM) J217
The control module is part of the mechatronics unit in the transmission.

The switching point is calculated automatically (depends on driving situation and driving resistance).

Advantages:
^ Gear changes are timed for maximum fuel economy.
^ Maximum engine output is always available
^ Individual adaptation of gear change points in all driving situations
^ Gear change points are infinitely variable

Self-diagnosis
Before performing repairs to the automatic transmission, determine the cause of the fault as precisely as possible using "Guided fault finding".

"Guided fault finding" is performed using the vehicle diagnostic, testing and information system VAS 5051 A.

Gear shift point variations for hills
An additional gear change map automatically selects gear changes for hills depending on accelerator pedal position and driving speed.
^ Gear change map for extreme uphill stretches is matched to engine output
^ Gear change map for extreme downhill stretches is matched to the braking effect of the engine
^ The engine braking effect can also be fully exploited via a specific gear, e.g. on hills when towing a trailer, by directly selecting a gear with the Tiptronic.