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

TRANSMISSION 722.931 in MODEL 218

Automatic transmission viewed from left

Fig 1: Identifying Intelligent Servo Module For Direct Select

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 INTERFACE (N150) 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 complete control unit software can be exchanged (replaced) with Xentry Diagnostics.

The software required for control unit programming can be found on the STAR DIAGNOSIS update DVD.

CAN data bus

The intelligent servo module for DIRECT SELECT is connected to the CAN connection of the vehicle over the drive train CAN (CAN C) 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:

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

Direct input signals

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

Direct output signals

None

CAN input signals

Electronic Stability Program control unit (N30/4) (except code (233) DISTRONIC PLUS) or Electronic Stability Program Premium control unit (N30/7) (with code (233) DISTRONIC PLUS)

Wheel speeds
Status of service brake

Electronic ignition lock control unit (N73)

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

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

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

Control unit for fully integrated transmission control (Y3/8n4)

Specified position of range selector lever

CAN output signals

Control unit for fully integrated transmission control (Y3/8n4)

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

Instrument cluster (A1)

Selector lever position

The ME-SFI [ME] control unit (N3/10) is the interface between the drive train CAN and chassis CAN (CAN E).

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 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 routes the selector lever position sent by the fully integrated transmission control unit over the drive train CAN to the ME-SFI [ME] control unit. The ME-SFI [ME] control unit sent a signal over the chassis CAN to instrument cluster (A1), which actuates the gear indicator (A1p12).

At "circuit 15 OFF" the intelligent servo module for DIRECT SELECT routes the selector lever position sent by the DIRECT SELECT INTERFACE over the drive train CAN to the gear indicator. The signal path from the intelligent servo module for DIRECT SELECT to the gear indicator acts in this case just as with "Circuit 15 ON".

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.

Designation		Unit	Value	Remarks
Intelligent servo module for DIRECT SELECT (A80)
Power supply		V	13.5
Voltage limit:	minimum	V	9.0
Voltage limit:	maximum	V	16.0
Power consumption:	Stand-by	mA	200
	Operation	A	< 30
	Extended operation	A	40	Maximum 300 ms
Quiescent current		mA	0.2
Reverse polarity protection				No
Operating temperature range		°C	-40 - 140
Adjustment times between gear ranges		ms	300	"P and D"
		ms	< 150	"N and R"
		ms	< 150	"N and P"
		ms	< 150	"N and D"
Flash capability/coding capability				Yes/yes

Wiring diagram for intelligent servo module (ISM) control unit

A80

PE27.60-P-2101-97XAA