Gear Shift, Function - GF27.60-P-2000RR

Model 190 With Transmission 700.4 

Function requirements for shift operation, general 

• Circuit 30, drive train CAN (CAN C1) active
• Engine running
• Transmission not in limp-home mode
• Engine not in limp-home mode
• Complete and fault-free signal transmission via drive train CAN and chassis CAN 1 (CAN E1)

Shift operation, general 

To check the function requirements, the dual clutch transmission control unit (N15/13) reads in the following signals via the drive train CAN:

• Combustion engine running, from the ME-SFI control unit (N3/10) via the drive train CAN
• Engine running, signal from the ME-SFI control unit via the drive train CAN

The dual clutch transmission control unit determines the actual gear and the required target gear on the basis of the following information:

• Clutch pressure sensor K1 (Y3/11b1)
• Clutch pressure sensor K2 (Y3/11b2)
• System pressure sensor (Y3/11b3)
• Temperature sensor module (Y3/11b5)
• Dual clutch transmission output shaft RPM sensor (Y3/13n1)
• Dual clutch transmission hollow shaft RPM sensor (Y3/13n2)
• Dual clutch transmission internal shaft RPM sensor (Y3/13n3)
• Engine speed sensor (Y3/13n4)
• Shift fork position sensor 1 (Y3/12s1)
• Shift fork position sensor 2 (Y3/12s2)
• Shift fork position sensor 3 (Y3/12s3)
• Shift fork position sensor 4 (Y3/12s4)
• Pressure distributor position sensor (Y3/12s6)
• Gear set group oil temperature sensor (Y3/13b2)
• Accelerator pedal position from the ME-SFI control unit
• Selector lever position from the DIRECT SELECT INTERFACE (N150)
• Complete and fault-free transmission messages as well as the status of the Electronic Stability Program (ESP®), from the Electronic Stability Program control unit (N30/4)
• Wheel speed from the Electronic Stability Program control unit
• Transmission mode selected at the transmission mode rotary switch (S192), from the AMG gateway control unit (N93/9)
• Status of "M" transmission mode (S16/15), from AMG gateway control unit
• Status of steering wheel downshift button (S110/1) and steering wheel upshift button (S111/1), via steering wheel electronics (N135) from steering column tube module control unit (N80)
• Status of AMG ESP Sport Off button (S193/1) to Electronic Stability Program control unit

The dual clutch transmission control unit checks and actuates the following components:

• Shift rods regulation valve A (Y3/12y1)
• Shift rods regulation valve B (Y3/12y2)
• Shift rods regulation valve C (Y3/12y3)
• Shift rods regulation valve D (Y3/12y4)
• System pressure regulation valve (Y3/11y3)
• Clutch regulation valve K1 (Y3/11y4)
• Clutch regulation valve K2 (Y3/11y5)
• Clutch cooling regulation valve K1 (Y3/11y6)
• Clutch cooling regulation valve K2 (Y3/11y10)
• Clutch emergency shift switchover valve K1 (Y3/11y7)
• Clutch emergency shift switchover valve K2 (Y3/11y8)
• Pressure distributor switchover valve (Y3/12y5)
• Park pawl switchover valve (Y3/12y6)
• Park pawl locking solenoid (Y3/13b1)

Shifts, which could result in non-permissible high or low engine speeds, are not performed.

The DIRECT SELECT INTERFACE sends the selector lever position via the drive train CAN to the dual clutch transmission control unit. The dual clutch transmission control unit sends this via the drive train CAN to the ME-SFI control unit and to the Electronic Stability Program control unit via the drive train CAN, powertrain control unit and chassis CAN 1.

Reverse gear and neutral can only be engaged via the DIRECT SELECT INTERFACE.

The park pawl can be engaged by pressing the "P" button only when the vehicle is at a standstill.

On vehicles without CODE 498 (Japan version) or CODE 494 (USA version), the selected transmission mode remains active for 4 hours after the ignition cycle. After the 4 hours have expired, the vehicle is automatically started in transmission mode "C".

On vehicles with CODE 494 (USA version) or CODE 498 (Japan version), the "C" transmission mode is preset automatically after every ignition cycle.

Downshifts, which would result in a rotational speed which damages the engine, are stopped. This is indicated visually in the multifunction display (A1p13) of the instrument cluster.

Function sequence for manual gearshift mode 

The "M" transmission mode button can be used to select manual gearshift mode. The AMG gateway control unit receives the status of the "M" transmission mode button and forwards it over the drive train CAN to the dual clutch transmission control unit as well as over the user interface CAN to the instrument cluster. The activated manual gearshift mode is indicated indicator lamp in the "M" transmission mode button lighting up and "M" being shown on the multifunction display. In manual gearshift mode, the gears can be permanently manually selected using the steering wheel downshift button or the steering wheel upshift button. The response times match the previously active transmission mode.

The transmission only shifts back at low engine speeds, dependent on each gear.

Shifts, which could result in non-permissible high or low engine speeds, are not performed.

Function sequence, shifting from 1st gear to 2nd gear 

If 1st gear is engaged and the vehicle drives in 1st gear, then the following components are involved at the same time:

• Clutch K1 is engaged, the clutch K1 regulation valve and the clutch K1 emergency shift switchover valve are actuated by the dual clutch transmission control unit
• The park pawl is unlocked, i.e. the park pawl switchover valve is actuated by the dual clutch transmission control unit, the park pawl main valve supplies the hydraulic cylinder of the park pawl with oil pressure and the lock pawl is lifted out of the park pawl gearing, the locking finger of the park pawl locking solenoid keeps the lock pawl in the release position
• The pressure distributor is in the basic position, i.e. the pressure distributor switchover valve is not energized
• The shift rods A control valve is actuated by the dual clutch transmission control unit and the 1st to 3rd gear shift rod is slid hydraulically toward 1st gear

If now the shift into 2nd gear takes place, the following components are involved at the same time:

• The pressure distributor moves into the end position, i.e. the pressure distributor switchover valve is energized by the dual clutch transmission (DKG) control unit
• The control valve A shift rods remain actuated by the dual clutch transmission (DKG) control unit
• The 1st to 3rd gear shift fork is pushed hydraulically to the center position and 1st gear is disengaged. The 2nd to 6th gear shift fork is pushed hydraulically towards 2nd gear and 2nd gear is engaged
• Clutch K2 is engaged, the clutch K2 regulation valve is actuated by the dual clutch transmission control unit (the clutch K2 regulation valve is proportionally energized for reduction of control current at the clutch K1 regulation valve so that a smooth gear change is ensured), the clutch K2 emergency running mode switchover valve is permanently energized
• The clutch K1 regulation valve is now de-energized, the vehicle moves in 2nd gear

To conduct a shift operation in a higher gear or a gear lower than the currently engaged gear, the engaged gear has to be disengaged first.

The park pawl remains unlocked.

The shift function is divided up into the following function sequences:

• Function sequence for shifting up and down 
• Function sequence for manual gearshift mode 
• Function sequence, shifting from 1st gear to 2nd gear 
• Function sequence of revving up 
• Function sequence for "no power" in gear range "D" Plus when driving 

Function sequence for shifting up and down 

The status of the steering wheel downshift button or steering wheel upshift button is forwarded via the steering wheel electronics, steering LIN (LIN E1), steering column tube module control unit, chassis CAN 1, powertrain control unit (N127) and drive train CAN to the dual clutch transmission control unit and the ME-SFI control unit. In the transmission modes Sport "S", Sport Plus "S+" and comfort "C" the driver can select the following functions by operating the downshift steering wheel gearshift button or the upshift steering wheel gearshift button:

• Pressing the downshift steering wheel gearshift button once activates the gear limitation function or triggers the downshift function which, if the engine speed permits, causes the transmission to shift down to the gear that is one gear below the gear currently engaged. The function "Shift into optimum gear" is selected by pressing and holding the downshift steering wheel gearshift button. The gear is selected which permits the best acceleration of the vehicle depending on the transmission mode selected.
• Pressing the steering wheel upshift button once with gear limitation selected increases gearshift limitation by one gear (e.g. from 3rd gear to 4th gear).
• Pressing the upshift steering wheel gearshift button in gear range "D" once sends a request to upshift to the dual clutch transmission (DKG) control unit. This shifts up depending on the driving situation.
• Pressing and holding down the upshift steering wheel gearshift button cancels the gear limitation function completely (gearshift to "D").

The transmission mode selection is set via the transmission mode rotary switch. The status is sent via the AMG DRIVE UNIT LIN (LIN B11), AMG gateway control unit and drive train CAN to the dual clutch transmission control unit. To display the transmission mode, the status of the transmission mode rotary switch is sent via the AMG DRIVE UNIT LIN, AMG gateway control unit and user interface CAN (CAN HMI) to the instrument cluster (A1). In comparison with transmission mode "S", "S+" and "Race", the "C" transmission mode has a shorter shift range (shifting at low engine speed) and therefore a lower drive torque when starting off in a forward or reverse direction. Depending on how the accelerator pedal is operated it is possible to move off smoother, because the gears are not driven to maximum revs.

Suspension adjustment

To adjust the suspension, the status of the transmission mode rotary switch is sent via the AMG DRIVE UNIT LIN, AMG gateway control unit, drive train CAN, powertrain control unit and chassis CAN 1 to the Electronic Stability Program control unit.

Wheel speed

The dual clutch transmission control unit receives the wheel speed via the Electronic Stability Program control unit, chassis CAN 1, powertrain control unit and drive train CAN.

Short-term M program

The short-term M mode is a temporary mode that is activated when the steering wheel gearshift buttons 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 undershooting a minimum speed (e.g. stopping), upon recognition of a lateral acceleration or if the vehicle is in a deceleration phase. If none of the stated criteria are active anymore, the short-term M mode remains active for a specified period of time. After this remaining time has elapsed, a switch is made back to the initial shift program. In addition, the driver is shown a recommended shift operation in the instrument cluster. This is part of the gearshift recommendation that is also integrated. The driver can prematurely cancel the short-term M mode through specific actions, e.g. if he/she presses and holds the steering wheel upshift button, if the gear range changes or if he/she changes the transmission mode. If one of these preconditions is met, a switch is made back to the initial shift program.

The clutch emergency running mode switchover valve K1 and the clutch emergency running mode switchover valveK2 remain energized when the clutch control valveK1 or clutch control valve K2 are intact. If, for example, the clutch K1 regulation valve is defective (e.g. it sticks), the clutch K1 emergency running mode switchover valve is de-energized, the pressure in clutch K1 is reduced and the power flow is interrupted.

Function sequence of revving up 

The double-clutching function is active in all transmission modes.

When shifting down, the task of the double-clutching function is to support the synchronization work at the dual clutch and to adjust the engine speed to the target engine speed of the target gear.

The DKG control unit transmits an increasing torque request via the drive train CAN to the ME-SFI control unit which this converts.

However, the motor speed does not rise above the required speed range (target engine speed of the target gear).

The double-clutching function ensures a faster gear change with low reaction torque.

The vehicle receives more driving stability when shifting down due to the quicker shifts and lower disturbing torque on the rear axle.

No power in gear range "D" Plus (KID+) in Comfort ("C") Transmission mode 

Function sequence for "no power" in gear range "D" Plus when driving 

• Vehicle between slight downhill gradient and slight uphill gradient
• Vehicle speed in extended "intercity range" (between approx. 60 km/h and 160 km/h)
• No power in gear range "D" Plus (KID+), selected transmission mode "C" and active ECO LED
• Transmission oil temperature > 40°C
• Accelerator pedal release not too fast
• Distance to vehicle in front adequate
• No trailer operation
• Lateral acceleration not too great

The function sequence of "no power" in gear range "D" Plus is deactivated when the vehicle is driving, if the following conditions are met:

• Brake applied more heavily
• Accelerator pedal position > 0
• Selector lever or steering wheel buttons actuated
• Distance to vehicle in front too small

The dual clutch transmission control unit receives the braking torque via the Electronic Stability Program control unit, chassis CAN 1, powertrain control unit and drive train CAN

Oil cooling

The powertrain control unit actuates the transmission cooling coolant circulation pump (M13/7) via the drive train LIN (LIN C3). This ensures that the oil is circulated.

	Electrical function schematic for shift operation		PE27.19-P-2057-97HBA
	Overview of system components for dual clutch transmission		GF27.10-P-9994RR