Transmission Control, Function - GF27.60-D-2002HAG
TRANSMISSION 722.9 in MODEL 906
Function requirements for transmission control, general
- "Circuit 87 ON"
- Function test of control unit (Y3/8n4) completed
Transmission control, general
The transmission control actuates the following actuators electronically:
- Working pressure control solenoid valve (Y3/8y1)
- Clutch control solenoid valve K1 (Y3/8y2)
- Clutch control solenoid valve K2 (Y3/8y3)
- Clutch control solenoid valve K3 (Y3/8y4)
- Brake control solenoid valve B1 (Y3/8y5)
- Brake control solenoid valve B2 (Y3/8y6)
- Brake control solenoid valve B3 (Y3/8y7)
- Torque converter lockup clutch control solenoid valve (Y3/8y8)
The control solenoid valves are located in the hydraulic valve body assembly. This implements the hydraulic functions.
The function of the electric controller unit (Y3/8) basically consists in the evaluation of various input signals relevant to the transmission function. Depending on this the control solenoid valves are actuated which for their part determine the working pressure, the gear ratio of the transmission (gear selection), and the torque converter lockup.
Transmission control function sequence
The function sequence is described in the following steps:
- Function sequence for basic shift program
- Function sequence for electronic and hydraulic transmission control
- Function sequence for kickdown
- Function sequence for limp-home mode
Function sequence for basic shift program
The basic shift program includes upshift and downshift characteristics for all 7 gears, designed for:
- Empty vehicle
- Warm operating condition
- Smooth road
- Sea level
The shift programs are adapted by offsetting the characteristics, depending on:
- Vehicle load
- Change in driving resistance
- Pedal movement
The control unit monitors and shifts depending on:
- Vehicle speed
- Selector lever position
- Accelerator pedal position
- Signals on the engine compartment 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
Function sequence for electronic and hydraulic transmission control
Whilst the electronic transmission control takes over the gear selection and adaptation of pressures to the torque to be transmitted, the power supply control of the transmission takes place via the hydraulic elements of the electric controller unit. The oil supply for the hydraulic elements such as actuators, torque converters and hydraulic transmission control is provided through an oil pump (primary pump) connected to the torque converter or through the electric transmission oil pump (M42) (with code (MJ7) ECO start). The transmission control system makes possible a precise adaptation of pressures to the respective operating states 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.
With code (MJ7) ECO start, the electric transmission oil pump ensures that the hydraulic system is supplied with oil when the internal combustion engine is switched off. It also supports the primary pump when the combustion engine is operating in the low speed range. This is actuated through the transmission oil auxiliary pump control unit (N89).
Function sequence for kickdown
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 sent by the CDI control unit (N3/28) (with engine 651) or the CDI control unit (N3/30) (with engine 642) over the engine compartment-CAN to the control unit.
Based on this information the control unit actuates the control solenoid valve so that the upshifts and downshifts take place at increased engine speed in order to achieve maximum performance. The forced downshift into the next lower gear is performed when transmission temperatures are too high and lower vehicle speed.
Function sequence for limp-home mode
If the signals are implausible, the transmission control system is only partially operational and switches to the programmed emergency performance map.
The driver can use the ESM control unit (N15/5) selector lever to select the desired gear ranges "P, R, N, and D".
The driver can choose been forward and reverse travel, engage the park pawl or, when in neutral, interrupt the power flow between torque converter and transmission.
| CDI control unit, component description | N3/28 Engine 651.9 |
GF07.16-D-6000HD |
| N3/30 ENGINE 642.898 in MODEL 906 with CODE (MG5) Engine OM 642 DE 30 LA, 140 kw (190 hp) 3800 RPM with CODE (MH1) Low-pollutant engine EPA 10/CARB with CODE (ZU7) Canada national version ENGINE 642.898 in MODEL 906 with CODE (MG5) Engine OM 642 DE 30 LA, 140 kw (190 hp) 3800 RPM with CODE (MH1) Low-pollutant engine EPA 10/CARB with CODE (ZU8) USA national version * Only for USA, Canada, Mexico |
GF07.16-D-6000HU | |
| N3/30 ENGINE 642.8 in MODEL 906 with CODE (MG5) Engine OM 642 DE 30 LA, 140 KW (190HP) 3800 RPM except CODE (ZU7) Canada national version except CODE (ZU8) USA national version |
GF07.16-S-6000SA | |
| Electronic selector lever module control unit, component description | N15/5 | GF27.19-D-5300H |
| Transmission oil auxiliary pump control unit, component description | N89 With code (MJ7) ECO start |
GF27.19-D-4030HAG |
| Fully integrated transmission control unit, component description | Y3/8n4 | GF27.60-D-5165HAG |
| Electric transmission oil pump component description | M42 With code (MJ7) ECO start |
GF27.57-D-1020HAG |
| Electric controller unit, component description | Y3/8 | GF27.19-D-5145HAG |
| Working pressure control solenoid valve, component description | Y3/8y1 | GF27.19-D-5170HAG |
| K1 clutch control solenoid valve, component description | Y3/8y2 | GF27.19-D-5171HAG |
| K2 Clutch control solenoid valve, component description | Y3/8y3 | GF27.19-D-5172HAG |
| K3 Clutch control solenoid valve, component description | Y3/8y4 | GF27.19-D-5173HAG |
| B1 Multidisk brake control solenoid valve, component description | Y3/8y5 | GF27.19-D-5174HAG |
| B2 multidisk brake control solenoid valve, component description | Y3/8y6 | GF27.19-D-5175HAG |
| B3 Multidisk brake control solenoid valve, component description | Y3/8y7 | GF27.19-D-5176HAG |
| Torque converter lockup clutch control solenoid valve, component description | Y3/8y8 | GF27.19-D-5177HAG |