GF27.60-P-2000ACM Gear Shift, Function
GF27.60-P-2000ACM Gear shift, function
- TRANSMISSION 722.643/649
- refinement package
- as of model year 09
Function requirements for shift operation, general
^ Circuit 87 ON
^ Circuit 61 (engine running)
^ Motor speed from ME-SFI [ME] control unit (N3/10)
^ Transmission not in limp-home mode
^ Engine compartment CAN (CAN C) signals
Shift operation, general
The electric controller unit (Y3/6) converts the electrical signals coming from the ETC control unit (N15/3) into hydraulic signals. The electronic selector lever module control unit (N15/5) passes on the selector lever positions "P, R, N, D" to the ETC control unit, taking into account various information. The MINUS steering wheel gear shifter (S110/1) and PLUS steering wheel gear shifter (S111/1) (with code (428) Steering wheel shift paddles) enables preselection of the shifting range up to which the transmission can shift.
The shift range is displayed in the instrument cluster (A1). The shift range can be changed in the forward gears while driving, but the ETC control unit prevents a shift at unacceptably high or low engine speeds.
Shift operation, function sequence
The function sequence is subdivided into the following steps:
^ Function sequence for upshift and downshift
^ Function sequence for shift to 1st. gear
^ Function sequence for shift phase
^ Function sequence for shift to 2nd. gear
^ Function sequence for revving up with model 230.479 with code (P99) Special model "AMG Black Series"
Function sequence for upshift and downshift
In the transmission modes Sport "S" and Comfort "C" the driver can select the following functions by operating the selector lever (touch mode (±)) or the MINUS steering wheel gear shifter and the PLUS steering wheel gear shifter (with code (428) Steering wheel shift paddles):
One press towards "-" activates the gear limitation or touchshift 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 direction "+" in gear range "D" sends an upshift request to the transmission (the transmission shifts up depending on the driving situation). Pressing and holding toward cancels the gear limitation function completely (gearshift to "D"). In transmission mode Comfort "C" in comparison with the transmission mode Sport "S" a shorter shift range (shifting at low engine speed) and therefore a lower drive torque is available. This enables a gentler start-off as the gears are not driven to the limit. In the manual "M" transmission mode (except model 230.477 with code (494) USA version) the individual gears "1, 2, 3, 4, 5" can be selected directly using the MINUS and PLUS steering wheel gear shifters (with code (428) Steering wheel shift paddles).
Reverse gear, park position and neutral can only be selected by way of the electronic selector lever module control unit.
The manual "M" transmission mode (except model 230.477 with code (494) USA version) is no longer active after a change of status from "circuit 15 OFF" to "circuit 15 ON". It is always started in the last selected transmission mode "S" or "C".
On model 230.479 with code (P99) Special model "AMG Black Series" the driver in manual "M" transmission mode can choose between the "M1" transmission mode and the "M2" transmission mode using the Standard (M1)/Sport (M2) manual transmission switch (S16/14s1). If the driver uses the transmission mode switch (S16/5) to select the manual "M" transmission mode, then the "M1" transmission mode is always active and the left light-emitting diode (LED) in the Standard (M1)/Sport (M2) manual transmission switch. If the driver now presses the Standard (M1)/Sport (M2) manual transmission switch then the "M2" transmission mode is active and the right LED also lights up. Pressing the Standard (M1)/Sport (M2) manual transmission switch initiates a change to the "M1" transmission mode. Transmission mode "M2" has shorter shift times in comparison to transmission mode "M1 ".
On model 230.479 with code (P99) Special model "AMG Black Series" the shift up instruction in the instrument cluster is used to ask the driver to shift up in the manual "M" transmission mode to the next higher gear.
Function sequence for shift to 1st. gear
The end face of the 1 - 2 or 4 - 5 command valve is kept depressurized via the 1-2 and 4-5 shift solenoid valve. Working pressure is applied via the 1 - 2 or 4 - 5 holding pressure shift valve to the multidisk brake B1 The multidisk clutch K1 is unpressurized.
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.
Function sequence for shift phase
Via the 1-2 and 4-5 shift solenoid valve the shift valve pressure is switched so that it acts on the end face of the 1 - 2 or 4 - 5 command valve. As a result command valve 1 - 2 or 4 - 5 is displaced and the shift pressure coming from the 1 - 2 or 4 - 5 shift pressure shift valve is routed over the 1 - 2 or 4 - 5 command valve to the multidisk clutch K1 Overlap pressure is applied to the multidisk brake B1 at the same time from the 1 - 2 or 4 - 5 overlap regulating valve.
The pressure of the multidisk brake B1, which is applied at the face of the shift pressure shift valve 1 - 2 or 4 - 5, is replaced by the working pressure. The increasing shift pressure at the multidisk clutch K1 acts on the annular surface on the 1 - 2 or 4 - 5 overlap regulating valve and reduces the overlap pressure regulated by the 1 - 2 or 4 - 5 overlap regulating valve. At a corresponding pressure level at the 1 - 2 or 4 - 5 holding pressure shift valve this changes over.
Function sequence for shift to 2nd. gear
Once the gear change is complete via the 1-2 and 4-5 shift solenoid valve the pressure on the end face of the 1 - 2 or 4 - 5 command valve is reduced and this is moved into the basic position. Working pressure now reaches the multidisk clutch via the 1 - 2 or 4 - 5 holding pressure shift valve and the 1 - 2 or 4 - 5 command valve K1.
The multidisk brake B1 is switched off (unpressurized). The spring in the shift pressure shift valve 1 - 2 or 4 - 5 shifts this into the basic position.
Function sequence for revving up with model 230.479 with code (P99) Special model "AMG Black Series"
The revving-up function is active in the "S", "M" ("M1" or "M2") transmission mode.
When shifting down (deceleration fuel shutoff) the revving-up function is responsible for supporting re-synchronization in the subsequent gear on the engine side.
Closing the transmission-internal clutch or brake, which is activated in the subsequent gear, causes the engine speed to increase to a higher speed level.
The electronic transmission control (EGS) control unit sends an increase torque request over the engine compartment-CAN to the ME-SFI [ME] control unit, which then realizes it and therefore briefly increases the engine speed. The engine speed increase however does not rise above the required engine rpm range (target speed in new gear).
The revving-up function serves to guarantee a faster gear change with lower tilting moment.
The vehicle is given greater driving stability through the faster gear changes and lower interference torque on the rear axle.
