GF27.60-P-2002GGA Transmission Control, Function
GF27.60-P-2002GGA Transmission Control, Function
TRANSMISSION 722.902 in MODEL 463.306 /336 /346 up to 31.5.12 as of Model Year 2011 /YoM 10
TRANSMISSION 722.904 in MODEL 463.202 /222 /236 /237 up to 31.5.12 as of Model Year 2009 /YoM 08
TRANSMISSION 722.902 in MODEL 463.303 /340 /341 up to 31.5.12 as of Model Year 2009 /YoM 08
1 Speed signal
2 Selector lever position
3 Touch shift signal
4 Engine load and speed
5 Accelerator pedal signal value
6 Kick-down signal
7 Actuation of control solenoid valves
8 Gear and transmission mode display signal
9 Fault message
10 Engine torque adaptation request
A1 Instrument cluster
B37 Accelerator pedal sensor
N3/9 CDI control unit (with diesel engine)
N3/10 ME-SFI [ME] control unit (with gasoline engine)
N15/5 Electronic selector lever module control unit
Y3/8n4 Fully integrated transmission control (VGS) control unit
Y3/8y1 Control solenoid valve Working pressure (VGS)
Y3/8y2 Control solenoid valve Clutch K1 (VGS)
Y3/8y3 Control solenoid valve Clutch K2 (VGS)
Y3/8y4 Control solenoid valve Clutch K3 (VGS)
Y3/8y5 B1 brake control solenoid valve (VGS)
Y3/8y6 B2 brake control solenoid valve (VGS)
Y3/8y7 B3 brake control solenoid valve (VGS)
Y3/8y8 Torque converter lockup clutch control solenoid valve (VGS)
CAN C Drive train CAN
Function requirements for transmission control, general
^ Circuit 87 ON
^ Function test of fully integrated transmission control unit (VGS) carried out
Transmission control, general
The transmission control system electronically actuates the actuators (control solenoid valves). The valves are positioned on the electric controller unit (VGS). This implements the hydraulic functions. The function of the electric controller unit (VGS) is primarily to evaluate various input signals that are relevant to transmission operation. Based on this, eight electromechanical hydraulic valves are actuated which determine the gear ratio of the transmission (gear selection), the working pressure and the torque converter lockup.
Transmission control function sequence
The function sequence for the transmission control is split up into the following points:
^ Basic shift program
^ Electronic and hydraulic transmission control function sequence
^ Kick-down function sequence
^ Limp-home mode function sequence
Basic shift program
The basic shift program includes upshift and downshift characteristics for all 7 gears, designed for:
- Empty vehicle
- Operating temperature
- Level road
- Sea level
The fully integrated transmission control unit (VGS) monitors and shifts depending on:
- Vehicle speed
- Selector lever position
- Accelerator pedal position
- Signals over the drive train CAN (CAN C)
Slow accelerator release:
- Undesired downshifts in the upper vehicle speed range are prevented
Rapid accelerator release:
- Upshifting to the next gear up is prevented and only permitted again when the vehicle accelerates slowly
Electronic and hydraulic transmission control function sequence
Whilst the electronic transmission control takes over the gear selection and adaptation of pressures to the torque to be transmitted, the power supply of the transmission is controlled via the hydraulic elements of the electric controller unit (VGS). The oil supply to the hydraulic elements, such as the torque converter, the shift elements and the hydraulic transmission control, is provided by way of an oil pump connected to the torque converter. The transmission control system makes possible a precise adaptation of pressures to the respective operating conditions and to the engine output during the gearshift phase, resulting in a significant improvement in shift quality. It is possible to reach the engine rpm limit in the individual gears using full throttle and kickdown.
The transmission control system prevents impermissibly high engine speeds with a downshift lockout device. Furthermore, the transmission control system offers the advantage of a flexible adaptation to various vehicle and engine versions.
Kick-down function sequence
The driver's wish for maximum acceleration is met by the kickdown function.
The kickdown function is activated as of a pedal travel > 90 %.
The "kick-down" signal is routed from the CDI control unit or ME-SFI [ME] control unit to the fully integrated transmission control unit via the drive CAN
Based on this information the fully integrated transmission control (VGS) control unit actuates the control solenoid valves so that the upshifts and downshifts take place at higher engine speeds in order to achieve maximum performance.
Limp-home mode function sequence
If the signals are implausible, the transmission control system is only partially operational and switches to the programmed emergency performance map.
The electronic selector lever module control unit enables the driver to select the required gear ranges "P, R, N, D".
The driver can choose been forward and reverse travel, engage the park pawl or interrupt the power flow between torque converter and transmission in the neutral position.
