System Overview, Automatic Transmission

The AF 22 (B204L/B234i/B258i) is an electronically controlled 4-speed automatic transmission which, in combination with different engine versions, is fitted in the Saab 900.

The transmission is controlled by an electronic system in which a transmission control module continually processes input signals and information received from a number of sensors. On the basis of the results obtained, it controls the automatic transmission's hydraulic system.Compared with conventional hydraulically controlled transmissions, the AF22 has the following advantages:

^ Improved shifting performance and smoother shifting as torque is reduced when shifting takes place.

^ Lower fuel consumption through a drive program designed to optimize consumption.

^ Option of selecting different drive programs: NORMAL, SPORT, WINTER.

^ Reduced mechanical stresses on the entire drivetrain.

^ Self-diagnosis and storage of diagnostic trouble codes