GF27.10-P-0001RT Automatic Transmission (AT), Function

GF27.10-P-0001RT Automatic transmission (AT), function
- TRANSMISSION 722.9
- up to model year 08

Component Identification:

Transmission 722.9 is an electronically controlled automatic transmission with 7 forward gears and 2 reverse gears. All the transmission functions and transmission components for this automatic transmission are combined in one assembly module. Integrating the electrohydraulic controller unit in transmission 722.9 minimizes the number of interfaces to the wiring harness. The electrohydraulic controller unit is installed below the transmission housing; the transmission oil is continuously flushed around the outside of the controller unit, which amongst other things, ensures the controller unit is cooled.

Transmission 722.9 can be roughly divided into the following component groups:
^ Torque converter with torsional damper and torque converter lockup clutch.
^ Oil pump to produce the necessary oil pressure and for reliable lubrication of the actuators and bearing points.
^ The transmission housing for the mechanical transmission components and electrohydraulic controller unit. The transmission housing is made of a light alloy.
^ The mechanical transmission components, consisting of a Ravigneaux gear set, front single planetary gear set, rear single planetary gear set and a park pawl. Additionally, a multi-disk clutch K1, multi-disk clutch K2, multi-disk clutch K3, multi-disk brake B1, multi-disk brake B2, multi-disk brake B3 and the BR multi-disk brake are also integrated. Single-sided disks are used on multidisk clutch K1, on multidisk clutch K2 and on multidisk clutch K3 Single-sided disks are also used on multidisk brake B1 and on multidisk brake B3
On this type of lamella the friction lining is only applied on one side. Among other things, this improves heat distribution in the disk pack, the design of the disk pack is more compact, the load-bearing capacity is increased and the mass is reduced.
For the multi-disk brake B2 and BR multi-disk brake disks coated on both sides are also used.
^ Electrohydraulic controller unit consisting of the electric controller unit VGS (Y3/8), valve body and valve housing.

The following information are taken into account when shifting the drive positions:
^ Vehicle speed
^ Vehicle load
^ Driving resistance
^ Position and operating speed of accelerator pedal
^ Selected drive position and engaged gear
^ Selected transmission mode
^ Oil temperature and other information about the status of the transmission
^ Further signals which are available via the Controller Area Network bus class C (engine compartment) (CAN-C)

Data is exchanged with the following control units via CAN-C:
^ Instrument cluster
^ Intelligent servo module for DIRECT SELECT
^ CDI control unit (N3/9)
^ ME control unit
^ ESP control unit
^ Upper control panel control unit
^ EIS [EZS] control unit
^ Steering column module
^ Central gateway control unit

This involves the processing of the following data from other systems:

Intelligent servo module for DIRECT SELECT
^ Actual position of range selector lever

CDI control unit (with engine 642)
^ Start-off in 1st gear, aids engine warm-up
^ Shift line displacement, aids engine warm-up
^ Specified gear, lower and upper limit, aids engine warm-up
^ Shift line displacement, dependent on load condition of diesel particulate filter (DPF), a heavily loaded DPF results in slightly lower upshift speed for full-load and kick-down upshifts
^ Emergency operation of the common rail diesel injection, the pedal value is limited to approx. 20 %, the driveability of the vehicle is assured
^ Engine coolant temperature, used as substitute value in event of malfunction in transmission oil temperature sensor (VGS) (Y3/8s2)
^ Engine oil temperature, shift limitation is canceled
^ Requirement torque for Electronic Stability Program (Electronic-Stability-Program) (ESP), torque reduction or torque increase taking into account directional stability and road adhesion
^ Kickdown
^ Request "Torque converter lockup clutch OPEN" to increase the engine speed in the warm-up phase of the engine
^ Pedal value
^ Engine torque
^ Engine idle specified speed for the actuation of the torque converter lockup clutch
^ Engine-speed limitation function active, adaptations are deactivated in the fully integrated transmission control (VGS) control unit
^ Engine speed, for slip calculation of torque converter lockup clutch and for start of pressure calculation by fully integrated transmission control (VGS) control unit

ME-SFI [ME] control unit (except engine 642)
^ Active downshift for heating up the catalytic converter (TWC)
^ Shift line displacement to heat up the catalytic converter
^ Emergency operation of ME gasoline injection and ignition system (motor electronics) (ME), the pedal value is restricted to approx. 20 %, the vehicle driveability is thus assured
^ Engine torque
^ Start-up in 1st gear for warming up catalytic converter
^ Engine coolant temperature, used as substitute value in event of malfunction in transmission oil temperature sensor (VGS)
^ Engine oil temperature, shift limitation is canceled
^ Request "Torque converter lockup clutch OPEN" to increase engine speed in the warm-up phase of the engine
^ Engine idle specified speed for the actuation of the torque converter lockup clutch
^ Engine speed, for slip calculation of torque converter lockup clutch and for start of pressure calculation by fully integrated transmission control (VGS) control unit
^ Engine-speed limitation function active, adaptations are deactivated in the fully integrated transmission control (VGS) control unit
^ Kickdown
^ Selected torque ESP, torque reduction or increase taking directional stability and road adhesion into account
^ Specified gear, lower and upper limit to heat up the catalytic converter
^ Pedal value

ESP control unit
^ BAS release switch (A7/7s1), change of shift strategy, brake the vehicle, the fully integrated transmission control (VGS) shifts down earlier
^ Set brake torque, change of shift strategy, brake the vehicle, the fully integrated transmission control (VGS) shifts down earlier
^ Wheel speeds and direction of rotation, substitute values in event of malfunction of output speed sensor (VGS) (Y3/8n3)
^ ESP request shift into "N" (neutral), power flow interruption, transmission/rear axle
^ Vehicle lateral acceleration at center of gravity, adaptation of shift strategy, detection of dynamic driving style
^ Cruise control controls, a special shifting strategy for cruise control mode is filed in the fully integrated transmission control (VGS) control unit

Upper control panel control unit
^ Transmission mode switch

EIS [EZS] control unit
^ Refrigerant compressor (A9) ON
^ Circuit 50, influencing fault memory
^ Torque requirement of refrigerant compressor, torque correction

Steering column module
^ Signal from steering wheel gear shifter MINUS (S110/1), on model 251.077/177
^ Signal from steering wheel gear shifter PLUS (S111/1), on model 251.077/177
^ Signal from left steering wheel gear shifter (S110/2), except model 251.077/177
^ Signal from right steering wheel gear shifter (S111/2), except model 251.077/177
^ Signal from DIRECT SELECT gear selector switch (S16/13)

Central gateway control unit
^ Diagnosis

The following information is passed to other systems:

Instrument cluster
^ Gear selector switch position for multifunction display (A1p13)
^ Transmission mode selection for multifunction display
^ Pre-selected shift range for multifunction display

Intelligent servo module for DIRECT SELECT
^ Driver selected gear selector position
^ Actual position of transmission
^ Specified position of range selector lever

CDI control unit (with engine 642)
^ Engine torque requests, engine intervention when shifting
^ Limp-home of fully integrated transmission control (VGS)
^ Starter lockout release in selector lever position "P", "N"
^ Transmission variant, recognition of basic variants, difference in gear ratios
^ Status of torque converter lockup clutch
^ Actual gear and target gear, gear engaged, gear to be shifted, can be shown using STAR DIAGNOSIS

ME-SFI [ME] control unit (except engine 642)
^ Starter lockout release in gear selector switch position "P", "N"
^ Status of torque converter lockup clutch
^ Actual gear engaged and target gear, i.e. engaged gear, gear to be engaged, can be shown via STAR DIAGNOSIS
^ Transmission variant, recognition of basic variants, difference in gear ratios
^ Engine torque requests, engine intervention when shifting
^ Limp-home of fully integrated transmission control (VGS)

ESP control unit
^ Wheel torque factor, overall gear ratio
^ Transmission variant, recognition of basic variants, difference in gear ratios
^ Actual gear engaged and target gear, i.e. engaged gear, gear to be engaged, can be shown via STAR DIAGNOSIS

Central gateway control unit
^ Gear selector switch position for actuation of backup lamp function
^ Diagnosis