Component description for intelligent servo module for DIRECT SELECT - GF27.19-P-4020LEH

TRANSMISSION 722.950 in MODEL 221.095

TRANSMISSION 722.950 in MODEL 221.195

Automatic transmission viewed from left

Location

The intelligent servo module is located on the left of the transmission housing.

Fig 1: Identifying Intelligent Servo Module For Direct Select Component

Courtesy of MERCEDES-BENZ USA

Task

General

The gear selected by the driver "P, R, N, D" is not transferred via a rod (mechanical connection) from the control to the transmission but over an electronic connection ("wire"). This electronic connection consists of the DIRECT SELECT gear selector switch (S16/13) and the intelligent servo module. The overall system is called "Shift-by-wire".

Basic functions

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

Flash programming

The intelligent servo module is flashable, i.e. the complete software in the control unit can be changed (replaced) using the Diagnosis Assistance System (DAS).

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

CAN data bus

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

Input and output signals

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

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

Direct input signals

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

Direct output signals

None

CAN input signals

Front SAM control unit with fuse and relay module (N10/1)

Feedback "Circuit 54 ON" (additional information for park pawl)

Regenerative braking system control unit (N30/6)

Wheel speeds
Hybrid brake light switch position (S9/3) (for park pawl)

EIS [EZS] control unit (N73)

Request to engage selector lever position "P" or "N"

Fully integrated transmission control unit (VGS) (Y3/8n4)

Specified position of range selector lever

CAN output signals

Fully integrated transmission control unit (VGS) (Y3/8n4)

Actual position of range selector lever (with "Circuit 15 ON")

Instrument cluster (A1)

Selector lever position

Design

Shown in range selector lever position "N"

Fig 2: Identifying Range Selector Lever Position N

Courtesy of MERCEDES-BENZ USA

Function

The main motor is actuated and the drive gears induce the threaded spindle to rotate. The carriage moves to the required position and the range selector lever assumes the specified position selected. The actual position is recorded by the angle sensor and passed on to fully integrated transmission control unit (VGS) via the drive train CAN.

With "Circuit 15 ON" the intelligent servo module supplies the selector lever position transmitted by the fully integrated transmission control unit (VGS) to the gear indicator (A1p12). With "Circuit 15 OFF", the intelligent servo module transfers the selector lever position transmitted by the steering column tube module (N80) to the gear indicator.

With "Circuit 15 OFF" and the vehicle at a standstill, selector lever position "P" or "N" is engaged as soon as the transmitter key (A8/1) is pulled out of the EZS 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.

	Wiring diagram for intelligent servo module (ISM) control unit	A80	PE27.60-P-2101-97SAA
	Wiring diagram for fully integrated transmission control unit	Y3/8	PE27.19-P-2103-97SAA