Automatic Transmission/Transaxle: Description and Operation: Overview

Transmission Description

OVERVIEW
The AW F21 automatic transmission is a 6 speed, electronically controlled unit manufactured by Aisin AW in Japan. The transmission represents the latest in automatic transmission technology for a transverse, AWD (all-wheel drive) unit. The transmission features lock-up slip control, 'CommandShift' functions and automatic and driver selectable modes to give the optimum on and off road performance.
The transmission is controlled by a TCM (transmission control module) which contains software to provide operation as a semi-automatic 'CommandShift' transmission and a Gear Shift Module (GSM). The GSM is a rotary actuator which converts driver selections for P, R, N, D and S on the rotary TCS (transmission control switch) into rotary movement of the transmission selector shaft allowing the system to operate as a 'shift by wire' system, with no mechanical link to the transmission for drive selections.
The TCM (transmission control module) allows the transmission to be operated as a conventional automatic unit by selecting P, R, N, D, S on the TCS (transmission control switch). Rotation of the TCS (transmission control switch) to the 'S' position puts the transmission into electronic 'Sport' mode. Operation of the steering wheel mounted + or - paddle switches puts the transmission into electronic manual 'CommandShift' mode. For additional information, refer to External Controls Component Locations
The transmission system uses an auxiliary battery module which powers a failsafe system to allow the engagement of 'Park' in the event of vehicle power failure.
The AW F21 transmission has the following features:
- Designed to be maintenance free
- Transmission fluid is fill for life
- The torque converter features a controlled slip feature with electronically regulated lock-up control on gears 2 to 6
- Shift programs controlled by the TCM (transmission control module)
- TCM (transmission control module) has an adaptive capability to ensure efficient gear shift quality throughout the service life of the transmission
- Diagnostics available from the TCM (transmission control module) and the GSM via the high speed CAN (controller area network) bus.