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

TRANSMISSION 722.931 in MODEL 221.074/174, 216.374

Automatic transmission viewed from left

Location

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

Fig 1: Identifying Intelligent Servo Module Components For Direct Select

Courtesy of MERCEDES-BENZ USA

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 gear selector switch (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 complete software for the intelligent servo module for DIRECT SELECT can be replaced (re-installed).

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

CAN data bus

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

The BAS release switch (A7/7s1) on Model 221 is replaced as of 2.6.09 and on model 216 as of 1.9.10 by the brake light switch (S9/1). With code (233) DISTRONIC PLUS and code (239) ART Plus Light, the BAS release switch is still used.

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

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

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

ESP control unit (N47-5)

Wheel speeds
Position of BAS release switch or brake light switch (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)

Gear selector switch position

The central gateway control unit (N93) is the interface between the chassis CAN (CAN E) and the central CAN (CAN F).

Shown in range selector lever position "N"

Fig 2: Identifying Integrated Transmission Control Unit 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 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 for DIRECT SELECT forwards the gear selector switch position sent by the fully integrated transmission control unit (VGS) over the drive train CAN to the ME-SFI [ME] control unit (N3/10). The ME-SFI [ME] control unit sends a signal over the chassis CAN to the central gateway control unit and forwards it over the central CAN to the instrument cluster, which then actuates the gear indicator (A1p12). With "Circuit 15 OFF" the intelligent servo module for DIRECT SELECT routes it through the steering column tube module over the chassis CAN and on routes the gear selector switch position over the drive train CAN to the instrument cluster, which then actuates 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 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.

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

Designation		Unit	Value	Remarks
Intelligent servo module for DIRECT SELECT (A80)
Power supply		VV	13.5
Voltage limit:	minimum	VV	9.0
Voltage limit:	maximum	VV	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	Model 216	PE27.60-P-2101-97CAA
			Model 221	PE27.60-P-2101-97SAA