Fully Integrated Transmission Control Unit, Component Description - GF27.60-D-5165HAG

TRANSMISSION 722.9 in MODEL 906 

Top view of electric controller unit (Y3/8) 

Courtesy of MERCEDES-BENZ USA

Location 

The control unit is integrated in the electric controller unit which is located in the bottom of the transmission.

Task 

General 

The control unit determines the current operating condition of the vehicle and actuates all gear change sequences taking shifting comfort and the driving situation into consideration.

Flash programming 

The transmission control in the control unit is flashable, i.e. the complete software of the control unit can be changed (updated). The software required to program the control units is stored on the Star Diagnosis software DVD.

CAN data bus 

The control unit is connected to the CAN system of the vehicle via the engine compartment CAN (CAN C) and exchanges data with other control units.

Input and output signals 

The control unit evaluates the following input signals and outputs the corresponding output signals:

• Direct input signals 
• Direct output signals 
• CAN input signals 
• CAN output signals 

Direct input signals 

• Circuit 31
• Circuit 87
• Turbine wheel RPM sensor (Y3/8n1)
• Internal transmission speed RPM sensor (Y3/8n2)
• Output speed sensor (Y3/8n3)
• Selection range sensor (Y3/8s1)
• Transmission oil temperature sensor (Y3/8s2) (integrated in control unit)

Direct output signals 

• Working pressure control solenoid valve (Y3/8y1)
• Clutch K1 control solenoid valve (Y3/8y2)
• Clutch K2 control solenoid valve (Y3/8y3)
• Clutch K3 control solenoid valve (Y3/8y4)
• Brake B1 control solenoid valve (Y3/8y5)
• Brake B2 control solenoid valve (Y3/8y6)
• Brake B3 control solenoid valve (Y3/8y7)
• Torque converter lockup clutch control solenoid valve (Y3/8y8)

CAN input signals 

ESM [EWM] control unit (N15/5) 

• Selector lever position

EZS control unit (N73) 

• Drive authorization system (DAS) enable
• Circuit 50 signal, influence on fault storage

ESP control unit (N30/4) 

• Wheel speeds and direction of rotation, substitute values in the event of failure of the output speed sensor
• Adjusted braking torque, change of shift strategy, brake the vehicle, transmission shifts down earlier
• Vehicle lateral acceleration at center of gravity, adaptation of shift strategy, detection of dynamic driving style
• Cruise control operation, special shifting strategy
• Electronic Stability Program (ESP) request to shift to "N", power flow interruption
• Stop lamp switch (S9/1), change of shift strategy, brake the vehicle, transmission shifts down earlier
• ESP specified torque, torque reduction or torque increase

CDI control unit (N3/28) (with engine 651) and CDI control unit (N3/30) (with engine 642) 

Requests for catalytic converter heating

Switching request

• Engine torque
• Engine coolant temperature
• Engine speed
• Engine load
• Kickdown
• Engine speed limitation active
• Limp-home mode engine control

Trailer connection unit [AAG] control unit (N28/1) 

• Trailer recognition signal

Transmission oil auxiliary pump control unit (N89) (with code (MJ7) ECO start) 

• Actual value of duty cycle (applied actual current value)
• Diagnostic data

CAN output signals 

Instrument cluster (A1) 

• Selector lever position for display (A1p1)
• Display
• Actuation of EOBD indicator lamp (A1e17)

CDI control unit (with engine 651) and (with engine 642) 

• Drive position
• Actual gear, target gear Engine torque reduction request
• Starter enable in selector lever position "P" and "N"
• Engine idle specified speed (for actuation of the torque converter lockup clutch)
• Status of torque converter lockup clutch
• Emergency operation transmission control

Transmission oil auxiliary pump control unit (with code (MJ7) ECO start) 

• Specified value of duty cycle (applied current specification value)

ESP control unit 

• Wheel torque factor, overall gear ratio
• Actual gear, target gear
• Transmission variant, recognition of basic variants, difference in gear ratios