ETC [EGS] control unit, component description - GF27.19-P-4018CW

TRANSMISSION 722.6 in MODEL 204.0 up to Model Year 2008 

The electronic transmission control control unit determines the current operating condition of the vehicle and controls all the gear change sequences taking into account the shift comfort and driving situation.

It receives operating data as internal transmission input signals from the:

• Starter lockout contact
• Transmission oil temperature sensor (Y3/6b1)
• Rpm sensor 2 (Y3/6n2)
• Rpm sensor 3 (Y3/6n3)

The electronic transmission control control unit takes over the actuation of the solenoid valves for the modulating pressure and shift pressure and the gear change.

The required pressure, matched to the torque to be transmitted, is calculated from all input signals.

In addition a connection exists to the following control units:

• Instrument cluster (A1)
• Electronic selector lever module control unit (N15/5), via the drive train CAN
• CDI control unit (N3/9), via the drive train CAN
• Electronic Stability Program control unit (N30/4), via the chassis CAN
• Electronic ignition lock control unit (N73), via the chassis CAN
• Steering column module control unit (N80), via the chassis CAN
• Front SAM control unit with fuse and relay module (N10/1), via the chassis CAN

The CDI control unit (N3/9) is the interface between the drive train CAN and the chassis CAN, the front SAM control unit with fuse and relay module is amongst others the interface between the chassis CAN and the interior CAN and the Electronic Stability Program control unit is the interface to the vehicle dynamics CAN.

Information supplied from other systems: 

Electronic selector lever module control unit 

• The selector lever position

Electronic Stability Program control unit 

• The cruise control regulates a special shift strategy which for cruise control mode is stored in the electronic transmission control control unit.
• Electronic Stability Program (Electronic-Stability-Program) (ESP) desired shift operation in "N" (neutral), power flow interruption of rear axle gear
• Adjusted braking torque, change in shift strategy, brake the vehicle, the electronic transmission control (EGS) shifts down sooner
• Vehicle lateral acceleration at center of gravity, adaptation of shift strategy, detection of dynamic driving style
• Wheel speeds and direction of rotation, substitute values in the event of failure of RPM sensor 3
• Signal from BAS release switch (A7/7s1), change in shift strategy, brake the vehicle, the electronic (EGS) transmission control shifts down sooner

CDI control unit 

• Active downshift for heating up the catalytic converter (TWC)
• Specified gear, and lower/upper limit for heating up the catalytic converter
• Emergency operation of the Common-Rail Diesel Injection (CDI), the pedal value is limited to approx. 20 %, the driveability of the vehicle is ensured
• Shift curve offset for heating up the catalytic converter

• Engine coolant temperature is used as a substitute value in the event of the failure of the transmission oil temperature sensor
• Starting off in 1st gear to heat up the catalytic converter
• Engine oil temperature, shift limitation is canceled
• Selected torque ESP, torque reduction or increase taking directional stability and road adhesion into account
• Request for torque converter lockup clutch "Open" in the heating up phase of the catalytic converter, to increase engine speed
• Engine idle specified speed for the actuation of the torque converter lockup clutch
• Rpm limitation function active, adaptations in the electronic transmission control control unit are switched off
• Kickdown
• Engine speed, for slip calculation of the torque converter lockup clutch and for the start of pressure calculation by the electronic transmission control control unit
• Pedal value
• Engine torque

Electronic ignition switch control unit 

• Enable of stage 3 drive authorization system (DAS 3)
• Request of Key-P function
• Circuit 50, influencing fault memory

Steering column module control unit 

• Signal from steering wheel downshift button (S110/1), with code (428) Steering wheel shift buttons
• Signal from steering wheel upshift button (S111/1), with code (428) Steering wheel shift buttons

Front SAM control unit with fuse and relay module 

• Diagnosis

Information output to other systems: 

Instrument cluster 

• Selector lever position and selected shift range for the gear indicator (A1p12)
• Transmission mode selection for the transmission mode display (A1p16)

Electronic selector lever module control unit 

• Selector lever position of driver
• Specified position of the automatic transmission transmission mode button (S16/12)

Electronic Stability Program control unit 

• Wheel torque factor, overall gear ratio
• Actual gear engaged/target gear, i.e. engaged gear, gear to be shifted, can be shown via STAR DIAGNOSIS
• Transmission variant, recognition of basic variants, difference in gear ratios

CDI control unit 

• Engine torque requests, engine intervention when shifting
• ETC limp-home mode
• Starter enable in gear selector lever position "P", "N"
• Transmission variant, recognition of basic variants, difference in gear ratios
• Actual gear engaged/target gear, i.e. engaged gear, gear to be shifted, can be shown via STAR DIAGNOSIS
• Status of torque converter lockup clutch

Front SAM control unit with fuse and relay module 

• Diagnosis