Automatic transmission (AT), function - GF27.10-P-0001AHL

TRANSMISSION 722.9 (except 722.930/931) in MODEL 212 

Automatic transmission (AT), general 

Transmission 722.9 is an electronically controlled automatic transmission with 7 forward gears and 2 reverse gears. The gear ratios for the gear ranges are achieved by planetary gear sets. All the transmission functions and components for this transmission are combined in one assembly module.

Integration of the fully integrated transmission control controller unit (Y3/8) in the transmission minimizes the number of interfaces to the wiring harness.

As of model year 2013 / YoM AEJ12, the fully integrated transmission control 4 (VGS4-0) will be introduced.

The advantages of this are:

• Improvement in electromagnetic compatibility (EMC problem)
• Faster current control as well as compensation for on-board electrical system fluctuations, which leads to increased shift quality
• A more exact determination of shifting-relevant measurement values as well as a faster evaluation of the determined values

Service life can be increased, fuel consumption reduced, gearshift comfort improved and maintenance intervals revised by using optimized transmission components and a new automatic transmission fluid and by reducing working pressure and implementing software modifications.

• Model 212.0/1/2 with engine 272 and 273 as of 07/2010
• Model 212.0/2 with engine 274 as of 03/2013
• Model 212.0/2 with engine 276 and 278 as of 06/2011
• Model 212.1 with engine 276 as of 06/2013
• Model 212.0/2 with engine 271.8 as of 03/2011
• Model 212.0/2 with engine 642.8 as of 07/2010
• Model 212.0/2 with engine 651.9 as of 12/2010

Depending on the model, fuel-efficient and comfort-enhancing measures may be implemented at a later date.

The transmission can be subdivided into the following assemblies:

• Torque converter with torsional damper and torque converter lockup clutch
• Torque converter with integral centrifugal pendulum and torque converter lockup clutch (278.9, 642.8 and 651.9)
• Oil pump for producing the necessary oil pressure and for safe lubrication of actuators and bearing points
• Electrical transmission oil pump (M42) (with code (B03) ECO start/stop function) for generating required oil pressure and for reliable lubrication of the actuators and bearing points at engine OFF
• Transmission housing with mechanical transmission components (planetary gear sets, parking lock, multidisk clutches and multidisk brakes) and fully integrated transmission control controller unit

Data is exchanged with the following control units via the drivetrain CAN (CAN C):

• DIRECT SELECT intelligent servo module (A80)
• CDI control unit (N3/9) (for diesel engines)
• ME-SFI [ME] control unit (N3/10) (for gasoline engines)
• Transmission oil auxiliary pump control unit (N89) (with code (B03) ECO start/stop function)

For vehicles up to model refinement package 13 

Data is exchanged with the following control units via the chassis CAN (CAN E) with the interface of the CDI or motor electronics control units:

• Instrument cluster (A1)
• Electronic Stability Program control unit (N30/4) or Premium Electronic Stability Program control unit (with code (233) DISTRONIC PLUS) (N30/7)
• Front SAM control unit with fuse and relay module (N10/1)
• Electronic ignition lock control unit (N73)
• Steering column tube module control unit (N80)

As of model refinement 13, the existing chassis CAN will be replaced by chassis CAN 1 (CAN E1). An additional chassis CAN 2 (CAN E2) will be used between the instrument cluster and the front SAM control unit with fuse and relay module. The ME-SFI [ME] control unit or the CDI control unit is the interface between the drivetrain CAN and chassis CAN 1. The interface between chassis CAN 1 and chassis CAN 2 is formed by the front SAM control unit with fuse and relay module.

Further subfunctions are described separately:

• Transmission control, function 
• Key-P function 
• Shift operation, function 
• Power transmission, function