Component Description For Intelligent Servo Module For Direct Select - GF27.19-P-4020AHE

TRANSMISSION 722.9 (except 722.930) in MODEL 205 

Automatic transmission viewed from left 

Fig 1: Intelligent Gear Selector Servo Module (Direct Select) Component Location - Transmission 722.9 (Except 722.930) In Model 205 (Left Side View Of Transmission Shown)

Courtesy of MERCEDES-BENZ USA

Location 

The intelligent servo module for DIRECT SELECT is mounted on the left of the transmission housing.

Task 

General 

The driver's gear range request "P", "R", "N", "D" is not transmitted from the control to the transmission via a rod (mechanical connection) but by means of an electronic connection ("wire"). This electronic connection consists of the DIRECT SELECT lever (S16/13) and the intelligent servo module for DIRECT SELECT. The overall system is called "Shift-by-wire".

Basic functions 

The intelligent servo module for DIRECT SELECT receives the signals from the angle sensor which records the actual position of the range selector lever and eccentric shaft. The intelligent servo module for DIRECT SELECT controls the main motor and the emergency motor.

Flash programming 

The intelligent servo module for DIRECT SELECT is flashable, i.e., the control unit's complete software can be exchanged (replaced) with Xentry Diagnostics.

The software required for control unit programming can be found on the Star Diagnosis software DVD.

CAN bus 

The intelligent servo module for DIRECT SELECT is connected to the CAN network of the vehicle via the drive train CAN (CAN C1) and exchanges data with other control units.

Input and output signals 

The intelligent servo module for DIRECT SELECT evaluates the following input signals and outputs the appropriate output signals:

Evaluation of input factors 

The read-in input factors are evaluated by the fully integrated transmission control unit (Y3/8n4).

Direct line 

• Terminal 30
• Circuit 31
• Power supply for emergency motor as emergency path

Drive train CAN 

Signals from

• Fully integrated transmission control unit
• CDI control unit (N3/9) or ME-SFI [ME] control unit (N3/10)
• Powertrain control unit (N127)

Actuation of components 

The actuation of the components takes place via the following connections:

• Direct line 
• Drive train CAN 

Direct line 

• None

Drive train CAN 

Signal to

• Fully integrated transmission control unit
• CDI control unit or ME-SFI control unit
• Drivetrain control unit

The powertrain control unit and the electronic ignition lock control unit (N73) are interfaces (Gateway) for the exchange of function-relevant data for control units that are connected to the various Controller Area Network (CAN) bus systems.

Shown in range selector lever position "N" 

Courtesy of MERCEDES-BENZ USA

Function 

The main motor is actuated and the worm shaft is turned via the drive belt and the two drive pulleys. The carriage moves to the required position and the range selector lever assumes the specified position selected.

The actual position is detected by the angle sensor and sent via the drive train CAN to the fully integrated transmission control unit.

With "circuit 15 ON", the intelligent servo module for DIRECT SELECT sends the signal for the currently engaged gear range to the CDI control unit or ME-SFI [ME] control unit, to the fully integrated transmission control unit and to the powertrain control unit.

With "circuit 15 OFF" and vehicle standstill, selector lever position "P" or "N" is engaged, as soon as the transmitter key (A8/1) is removed from the electronic ignition lock control unit.

On vehicles with CODE 889 (Keyless Go), the request for selector lever position "P", with "circuit 15 OFF" and the vehicle at a standstill is made as soon as the driver door is opened.

If selector lever position "N" is engaged before "Circuit 15 OFF" and the driver door is opened after "Circuit 15 OFF", selector lever position "N" remains engaged.