GF27.60-P-2000ACW Gear Shift, Function
GF27.60-P-2000ACW Gear shift, function
- TRANSMISSION 722.618/640/646/695/699
Function requirements for chill operation general
^ Circuit 87 ON
^ Circuit 61 (engine running)
^ Engine speed from CDI control unit (N3/9) or ME-SFI control unit (N3/10)
^ Transmission not in limp-home mode
^ Drive train CAN (CAN C) signals
Shift operation, general
The automatic transmission electric controller unit (Y3/6) converts the electrical signals from the electronic transmission-control control unit (N15/3) into hydraulic signals.
The electronic selector lever module control unit (N15/5) routes the selector lever positions "P, R, N, D" to the electronic transmission-control control unit, taking different information into consideration. The steering wheel gearshift downshift button (S110/1) and steering wheel gearshift upshift button (S111/1) with code (428) Steering wheel shift paddles preselects the shift range up to which the transmission can shift up. The shift range is displayed in the instrument cluster (A1).
Although the shift range can be changed in the forward gears while driving, the electronic transmission-control control unit prevents a shift operation if the engine speed is too high or too low.
Shift operation, function sequence
The function sequence is subdivided into the following steps:
^ Upshifting and downshifting
^ Shifting, 1st gear
^ Shift phase
^ Shift in 2nd. gear
Upshifting and downshifting
In the transmission modes Sport "S" and Comfort "C" the driver can operate the selector lever (touch mode (+/-)) or the steering wheel gearshift downshift button or the steering wheel gearshift upshift button to select the following functions:
One press towards "2 activates the gear limitation or touch shift 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 "2 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").
In transmission mode Comfort "C", the available shift range (shifting at low engine speed) is shorter than in transmission mode "S" resulting in a lower drive torque when starting off in the forward or reverse direction.
This enables a gentler start-off as the gears are not driven to the limit.
In transmission mode Manual "M" (except code (494) USA version) the individual gears "1, 2, 3, 4, 5" can be engaged directly using the steering wheel shift upshift and downshift buttons.
Reverse gear, park position and neutral can only be selected by way of the electronic selector lever module control unit.
Manual transmission mode
Transmission mode Manual "M" is no longer active after ignition "OFF" -> "ON". The transmission always starts in the last selected transmission mode. ("S" or "C").
Shifting, 1st gear
The face of the command valve 1 - 2 or 4 - 5 (31a) is kept depressurized by gearshift solenoid valve 1-2 and 4-5 (Y3/6y3). Working pressure (p-A) is applied to multidisk brake B1 (21) through holding pressure shift valve 1 - 2 or 4 - 5 (28a).
The multi-disk clutch K1 (24) 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. possible due to the lack of excess force limitation.
Shift phase
Via the 1-2 and 4-5 gearshift solenoid valve the shift valve pressure is switched so that it acts on the end face of the command valve 1 - 2 or 4 - 5 (31a). This shifts the command valve 1 - 2 or 4 - 5 (31a) and the shift pressure (p-S), (coming from shift pressure shift valve 1 - 2 or 4 - 5 (29a) via command valve 1 - 2 or 4 - 5 (31a)), is routed to the multidisk clutch K1 (24). At the same time, the multi-disk brake B1 (21) is subjected to overlap pressure from the overlap regulating valve 1 - 2 or 4 - 5 (30a).
The pressure acting at the face of shift pressure shift valve 1 - 2 or 4 - 5 (29a) from multidisk brake B1 (21) is relieved by working pressure (p-A). The increasing shift pressure (p-S) at the multi-disk clutch K1 (24) acts on the annular surface of the overlap regulating valve 1 - 2 or 4 - 5 (30a) and reduces the overlap pressure regulated by the overlap regulating valve 1 - 2 or 4 - 5 (30a). With an appropriate pressure level at the 1 - 2 or 4 - 5 holding pressure shift valve (28a) this valve switches over.
Shift in 2nd. gear
After a successful gear change the pressure at the face of the command valve 1 - 2 or 4 - 5 (31a) is reduced via the gearshift solenoid valve 1-2 and 4-5 and this is set back to its original position. The working pressure (p-A) is routed via holding pressure shift valve 1 - 2 or 4 - 5 (28a) and command valve 1 - 2 or 4 - 5 (31a) to the multidisk clutch K1 (24).
The multi-disk brake B1 (21) is disengaged (unpressurized). The spring in shift pressure shift valve 1 - 2 or 4 - 5 (29a) pushes this to its basic position.
