Detailed Description FA 57: Notes

The FA 57 automatic transmission is an electronically-controlled 5-speed automatic gearbox with lock-up. The transmission casing constitutes one unit integrated with the engine, which is mounted transversely in the engine bay and drives the front wheels. The different gear positions, P-R-N-D-M+,M-, can be selected with gear selector mounted on a floor console between the front seats. Manual shifting can also be achieved using the buttons on the steering wheel (certain models).

The FA 57 is principally constructed around 4 planetary gear units, disc clutches, brakes, torque converter with lock-up coupling, which can be locked or allowed to slip in certain operating conditions, hydraulic and electronic control systems.

The transmission hydraulic system is controlled by a Control module TCM 502, which continuously processes information from its own sensors and other control modules.

The FA 57 has the following advantages over conventional hydraulic transmissions: 

• Improved shifting performance and smoother shifting as torque is reduced when shifting takes place.
• Reduced mechanical stresses on the entire drive train due to torque limitation.
• Improved fuel economy through a consumption-optimized driving program and lock-up on 3rd, 4th and 5th gears. To further save on fuel, a certain slip is allowed in the lock-up clutch. This means that a difference in speed of 50-200 RPM is allowed between the engine speed and the speed of the input shaft. This results in the engine pulling longer with lock-up engaged (although slipping) so that the transmission need not engage an open gear (power through the torque converter) or shift down.

  If the gearbox fluid temperature rises, a temperature-dependent program that protects the gearbox from heat damage is selected automatically. See "GEARBOX FLUID TEMPERATURE  " below.

• Possibility to change gear manually between 1st and 5th gears.
• Self-diagnosis and storage of diagnostic trouble codes.
• TCM sends and receives information from other control modules in the car through analogue signals and bus communication.

The transmission control module (TCM) controls principally: 

• Shift points
• System pressure
• Engagement of lock-up (fixed engagement or slip)

Transmission functions can be divided into three main groups: 

• Electronic control system
• Hydraulic control system
• Mechanical