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-optimised 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 lockup 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, see BUS AND DIAGNOSTICS 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