Engage gear range, function - GF27.60-P-3009AHS

TRANSMISSION 722.9 in MODEL 216.3 as of model year 2009 

/ YoM 08 

TRANSMISSION 722.9 in MODEL 216.3 (except 216.374) as of model year 2011 

/YoM 10 model refinement package 

TRANSMISSION 722.9 in MODEL 221.0 as of model year 2009 

/ YoM 08 

TRANSMISSION 722.9 in MODEL 221.0 (except 221.095) 

TRANSMISSION 722.9 in MODEL 221.0 (except 221.074) as of model year 2011 

/YoM 10 

TRANSMISSION 722.9 in MODEL 221.1 as of model year 2009 

/ YoM 08 

TRANSMISSION 722.9 in MODEL 221.1 (except 221.195) 

TRANSMISSION 722.9 in MODEL 221.1 (except 221.174) as of model year 2011 

/YoM 10 

Function requirements for engage gear range, general 

• Circuit 87 ON
• Circuit 61 ON

Engage gear range, general 

Each gear change is triggered by the fully integrated transmission control (VGS). In the process one component group is assigned to each shift operation.

One component group consists of the respective control solenoid valve, the regulating valve involved, the responsible shift valve and the required multidisk brake or multidisk clutch.

The pressure in the multidisk brake or multidisk clutch to be engaged is increased constantly while at the same time the pressure in the multidisk brake or multidisk clutch to be disengaged is reduced. The process is a smooth transition and the components affected are actuated directly. This makes it possible to downshift, even through several gears.

Function sequence for engage gear range 

Shift operation N to D (1st gear) 

In position "N" of the DIRECT SELECT gear selector switch (S16/13), multidisk brake B3 and multidisk clutch K3 are engaged. Shifting from position "N" to position "D" of the intelligent servo module for DIRECT SELECT (A80) means that the feed to the multidisk brake B2 is enabled by the selector valve. The fully integrated transmission control unit (VGS) (Y3/8n4) actuates brake B2 control solenoid valve (VGS) (Y3/8y6) and multidisk brake B2 is filled with oil.

The fully integrated transmission control unit (VGS) uses the RPM difference (actual slip) between the engine speed and turbine speed to detect whether multidisk brake B2 is full.

The brake B2 control solenoid valve (VGS) actuates the B2 and BR regulating valve which converts the present working pressure into shift pressure and passes it on to multidisk brake B2

In the fully integrated transmission control unit (VGS), the required slip (specified slip) is stored for the respective gear. Depending on the specified slip, the control pressure at the B2 and BR regulating valves is changed via the brake B2 control solenoid valve (VGS). The pressure in multidisk brake B2 is changed until the specified slip stored in the fully integrated transmission control unit (VGS) is reached.

The shift pressure produced by the regulating valve B2 and BR depends on the geometry of the regulating valve B2 and BR.

The BAS release switch (A7/7s1) will be replaced by the brake light switch (S9/1) in model 221 as of 2.6.09 and in model 216 as of 1.9.10. In vehicles with code (233) DISTRONIC PLUS and code (239) Adaptive cruise control Plus Light, the BAS release switch is still used.

No power in gear range "D" on model 221 as of model year 2011 /YoM 10 with engine 276.9, 642.8 

Function requirements 

• The vehicle speed v = approx. 15 km/h must be exceeded once after engaging gear selector switch position "D".
• The function sequence of "no power" in gear range "D" is activated in gear selector switch position "D" if the following conditions are met:

• The driver has braked the vehicle to a standstill
• Transmission temperature in range from 10°C to 110°C
• Coolant temperature in the range from 0°C to 120°C
• Accelerator pedal not applied
• Engine speed in range of 570 RPM to 1000 RPM
• Braking torque is at least 250 Nm and the brake light switch or the BAS release switch is actuated
• Transmission-internal uphill slope calculation value < 18 %
• Transmission mode "C" or "S" selected
• 1st gear engaged by the fully integrated transmission control
• Fully integrated transmission control is working faultlessly

Vehicle standstill can be reached via one of the following conditions:

• The driver has braked the vehicle to a standstill
• "HOLD function" (Hill Start Assist) is active

Function sequence 

The fully integrated transmission control reduces the flow at the brake B2 control solenoid valve (VGS) such that the shift pressure is reduced to the return spring level by regulating valve B2 and BR, bringing the multidisk brake B2 to a regulated slip. This leads to a reduction in transmission output torque when the vehicle is stationary and to a reduction in fuel consumption.

The function sequence of "no power" in gear range "D" is deactivated when at least one of the following conditions is met:

• Vehicle speed > 0 km/h
• Transmission oil temperature > 110°C
• Coolant temperature > 120°C
• Accelerator pedal applied
• Engine speed < 570/min or > 1000/min
• Braking torque < 250 Nm or brake light switch/BAS release switch is not actuated
• Transmission-internal uphill slope calculation value > 25 %
• A touch shift was detected or the gear selector switch was shifted out of gear selector switch position "D" to "N", "R" or "P"
• A system error in the fully integrated transmission control was detected

Overview of system components for automatic transmission (AT)

GF27.10-P-9992AHS