Gear shift, function - GF27.60-P-2000AHL

TRANSMISSION 722.9 (except 722.930/931) in MODEL 212 

Function requirements for shift operation, general 

• Circuit 87 ON
• Circuit 61 "ON" (engine running)
• Engine speed from CDI control unit (N3/9) or ME-SFI [ME] control unit (N3/10)
• Vehicle speed
• Transmission not in limp-home mode
• Drive train CAN (CAN C) signals

General shift operation for vehicles up to facelift 13 

The fully integrated transmission control controller unit (Y3/8) converts the electrical signals coming from the fully integrated transmission control unit (Y3/8n4) into hydraulic signals. The selector lever positions "P", "R", "N", "D" of the DIRECT SELECT lever (S16/13) are sent by the steering column tube module control unit (N80) to the chassis CAN (CAN E). The CDI control unit or ME-SFI control unit transfers the information to the drive train CAN. The intelligent servo module for DIRECT SELECT (A80) passes on the selector lever positions, taking into account various information, to the fully integrated transmission control unit.

The CDI control unit or ME-SFI control unit transfers the information to the drive train CAN. The intelligent servo module for DIRECT SELECT (A80) passes on the selector lever positions, taking into account various information, to the fully integrated transmission control unit.

The intelligent servo module changes the position of the selection range lever which is passed on to the selection range sensor (Y3/8s1). The shift range is displayed in the instrument cluster (A1).

Although the shift range can be changed in the forward gears while driving, the fully integrated transmission control unit prevents a shift operation if the engine speeds are too high or too low.

For vehicles as of facelift 13 the current chassis CAN will be replaced by the chassis CAN 1 (CAN E1). A second chassis CAN 2 (CAN E2) is networked between the instrument cluster and the front SAM control unit with fuse and relay module (N10/1).

Function sequence for shift operation 

The function sequence is described in the following steps:

• Function sequence for shifting up and down 
• Function sequence of gearshift 1 to 2 

Function sequence for shifting up and down 

In the Sport "S" and Comfort "C" or Economy "E" transmission modes, the driver can select the following functions by operating the downshift steering wheel gearshift button (S110/1) or the upshift steering wheel button (S111/1) with code (428) steering wheel shift paddles:

For vehicles up to facelift 13 

One press toward "-" activates the gear limitation function (a downshift is made to the gear that lies exactly one below the currently selected one if the engine speed allows).

Pressing and holding towards "-" selects the "Shift to optimal gear" function (the gear which allows the best vehicle acceleration is selected).

One press toward "+" with the gear limitation function selected increases gearshift limitation by one gear (e.g. from 3 to 4).

One press toward "+" in gear range "D" sends an upshift request to the transmission (the transmission shifts up if the driving situation allows).

Pressing and holding toward "+" cancels the gear limitation function completely (gearshift to "D").

As of model year 11/AEJ 10, the labeling on the automatic transmission mode button (S16/12) and the display in the instrument cluster will be changed from Comfort ("C") transmission mode to Economy ("E") transmission mode.

The gear limitation is replaced by the function "Short-term M mode". The short-term M program is a temporary program that is activated when the steering wheel gearshift buttons or the DIRECT SELECT lever are operated. Pressing in the positive (+) direction triggers an upshift and pressing in the negative (-) direction triggers a downshift, insofar as this is permissible. If not, the current gear is maintained. After a specified time window, this function deactivates again automatically. The activated time can be extended by a minimum speed being dropped below (e.g. stopping), where lateral acceleration is detected by the yaw rate sensor for lateral and longitudinal acceleration (B24/15) or if the vehicle is in a deceleration phase. If none of the stated criteria are active anymore, the M mode remains active for a prescribed remaining time. After this remaining time expires, the initial shift mode is returned to.

The driver can prematurely cancel the short-term M program through specific actions, e.g. if he/she operates and holds the upshift steering wheel gearshift button or the DIRECT SELECT lever in the "positive" direction, changes the gear range or changes the transmission mode. If one of these preconditions is met, a switch is made back to the initial shift program.

Compared to the Sport ("S") transmission mode, the Comfort ("C") / Economy ("E") transmission mode has a shorter shift range (shifting at low engine speed) and therefore a lower torque is available when starting off forwards and starting off in reverse.

This enables a gentler start-off as the gears are not driven to the limit. In the Manual ("M") transmission mode with code 950 (Sport package) except code 494 (USA version) the individual gears "1", "2", "3", "4", "5", "6", "7" can be selected directly using the steering wheel downshift or upshift buttons.

Reverse gear, park position and neutral can only be shifted via the DIRECT SELECT lever.

Manual transmission mode with code 950 (Sport package) The Manual "M" transmission mode is no longer active after ignition "OFF" "ON". The vehicle then always starts off in the transmission mode last selected ("S" or "C" / "E").

Transmission mode "M" is only available with code 950 (Sport package). In vehicles without the sport package, transmission mode "M" is not available. In these vehicles, transmission mode "M" is replaced by the "short term mode M".

Function sequence of gearshift 1 to 2 

Multidisk brake B2, multidisk brake B3 and multidisk clutch K3 are engaged in 1st gear. When shifting from 1st gear to 2nd gear, multidisk brake B3 is disengaged and multidisk brake B1 is engaged.

The shift operation can be started by the fully integrated transmission control unit. Here, the multidisk brake B1 is filled and the pressure in multidisk brake B1 is increased continuously. Simultaneously the pressure in multidisk brake B3 is reduced.

This involves a flowing transition. When the 2nd gear torque is reached, the engine speed must be adapted to the 2nd gear level (elevation phase).

This speed adjustment is achieved by the pressure in the multidisk brake B1 being increased and, if necessary, engine torque being reduced via the CDI control unit or ME-SFI control unit.

A forced downshift occurs at excessively low rpm and a forced upshift occurs at an excessively high rpm.

When the vehicle is stationary the transmission automatically shifts into 1st gear. It is possible to start off both in 1st or 2nd gear.