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Home >> Mercedes Benz >> 2011 >> GL350 >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Automatic Transmission - 164 Chassis - 2 Of 2 >> Basic Knowledge >> Component description for intelligent servo module for DIRECT SELECT - GF27.19-P-4020AHZ

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

TRANSMISSION 722.902/903/904/906/907 in MODEL 164.1 as of model year 2009/CY 08 Model refinement package 

TRANSMISSION 722.902/903/904 in MODEL 164.8 as of model year 2009/CY 08 

TRANSMISSION 722.902/904/906/999 in MODEL 251.0 as of model year 2009/modification year 08 

TRANSMISSION 722.902/904/906/999 in MODEL 251.1 as of model year 2009/modification year 08 

Fig 1: Identifying Intelligent Servo Module For Direct Select
G10115613Courtesy of MERCEDES-BENZ USA

Location 

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

Task 

The task of the intelligent servo module for DIRECT SELECT is subdivided into the following projects:

General 

The driver's drive stage requirement "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 gear selector switch (S16/13) and the intelligent servo module for DIRECT SELECT. The overall system is called "Shift-by-wire". The intelligent servo module for DIRECT SELECT controls the main motor and the emergency motor.

Input and output signals 

Signal inputs and outputs 

Direct input signals 

IMPORTANT The intelligent servo module for DIRECT SELECT measures the position of the eccentric shaft via the eccentric shaft position sensor and the actual position of the range selector lever via the angle sensor.

Engine compartment CAN (CAN C) input signals 

Engine compartment CAN output signals 

Function 

Shown up to 31.8.08 

Fig 2: Identifying Intelligent Servo Module For Direct Select
G10115614Courtesy of MERCEDES-BENZ USA

Shown as of 1.9.08 

Fig 3: Identifying Intelligent Servo Module For Direct Select
G10115615Courtesy of MERCEDES-BENZ USA

The main motor (30) is actuated and the threaded spindle (33) is turned via the drive gears (39) (up to 31.8.08) or via the drive belts (42) and the two drive pulleys (41) (as of 1.9.08). The slider (32) moves into the required position and the range selector lever (35) assumes the specified nominal position.

The actual position is recorded by the angle sensor (36) and passed on to the fully integrated transmission control unit (VGS) via the engine compartment CAN.

IMPORTANT With "circuit 15 ON" the intelligent servo module for DIRECT SELECT passes the position of the DIRECT SELECT gear selector switch transmitted by the fully integrated transmission control unit (VGS) to the gear indicator (A1p12). With "circuit 15 OFF" the intelligent servo module for DIRECT SELECT forwards the DIRECT SELECT gear selector switch position transmitted by the steering column tube module (N80) to the gear indicator.

IMPORTANT With "circuit 15 OFF" and when the vehicle is stationary the position of DIRECT SELECT gear selector switch "P or N" is engaged as soon as the transmitter key (A8/1) is removed from the EIS (EZS) control unit.

IMPORTANT On vehicles with code (889) Keyless Go the request of the position of the DIRECT SELECT gear selector switch "P", takes place with "circuit 15 OFF" and when the vehicle is stationary, as soon as the driver's door is opened. If the position of the DIRECT SELECT gear selector switch "N" is engaged before "circuit 15 OFF" and the driver's door is opened after "circuit 15 OFF", the position of the DIRECT SELECT gear selector switch "N" remains engaged.

REFER TO SYSTEM WIRING DIAGRAMS Wiring diagram for intelligent servo module (ISM) control unit Model 164 PE27.60-P-2101-99MAA
    Model 251 PE27.60-P-2101-99RAA