Intelligent Servo Module (ISM) Control Unit For Direct Select, Component Description - GF27.19-S-4025TRA
Transmission 722.9 in model 447
Transmission 722.9 in model 448
Automatic transmission viewed from left
Location
The intelligent servo module (ISM) for DIRECT SELECT control unit (A80) is mounted on the left of the transmission housing.
Task
The gear request P, R, N, D of the driver is not sent via a rod (mechanical connection) from the control to the automatic transmission but rather by means of an electronic connection. This electronic connection consists of the DIRECT SELECT selector lever (S16/13) and the intelligent servo module (ISM) for DIRECT SELECT control unit (A80). The overall system is called "Shift-by-wire".
Basic functions
The intelligent servo module (ISM) for DIRECT SELECT control unit (A80) receives the signals from the angle sensor (35) which detects the actual position of the range selector lever (35) and of the eccentric shaft (34). The intelligent servo module (ISM) for DIRECT SELECT control unit (A80) controls the main motor (30) and the emergency motor (31).
Flash programming
The intelligent servo module (ISM) for DIRECT SELECT control unit (A80) is flashable, i.e. the control unit's complete software can be exchanged (replaced).
The software required to program the control units is stored on the Xentry diagnostics update DVD.
CAN bus
The intelligent servo module (ISM) for DIRECT SELECT control unit (A80) is connected to the CAN network of the vehicle via the drive train CAN (CAN C) and exchanges data with other control units.
Input and output signals
The intelligent servo module (ISM) for DIRECT SELECT control unit (A80) evaluates the following input signals and issues the corresponding output signals:
Evaluation of input factors
The read-in input factors are evaluated by the fully integrated transmission control (VGS) control unit (N15/11n4).
Direct line
- Circuit 30
- Circuit 31
- Power supply for emergency motor (31) as emergency path
Drive train CAN
Signals from
- Fully integrated transmission control unit (VGS) (N15/11n4):
- CDI control unit (N3/33) (with engine 651)
- ME-SFI [ME] control unit (N3/34) (with engine 274)
Actuation of components
The actuation of the components takes place via the following connections:
- Direct line
- Drive train CAN (CAN C)
Direct line
- None
Drive train CAN
Signal to
- Fully integrated transmission control unit (VGS) (N15/11n4):
- CDI control unit (N3/33) (with engine 651)
- ME-SFI [ME] control unit (N3/34) (with engine 274)
The gateway for user interface CAN control unit (N93/4) (only model 447.8), the CDI control unit (N3/33) (with engine 651) or ME-SFI control unit (N3/34) (with engine 274), the electronic ignition lock (EIS) control unit (N73) and the radio (Audio/COMAND) (N87/6) (only model 447.8) are interfaces (gateways) for the exchange of function-relevant data of the control units which are connected to the various CAN bus systems.
Shown in range selector lever position "N"
Function
The main motor (30) is actuated and the threaded rod (33) is turned by the drive belt (42) and the two drive pulleys (41). The carriage (32) moves to the required position and the range selector lever (35) assumes the specified position selected.
The actual position is detected by the angle sensor (35) and forwarded via the drive train CAN (CAN C) to the fully integrated transmission control (VGS) control unit (N15/11n4).
With "circuit 15 ON", the intelligent servo module (ISM) for DIRECT SELECT control unit (A80) sends the signal for the currently engaged gear range to the CDI control unit (N3/33) (with engine 651) or ME-SFI control unit (N3/34) and to the fully integrated transmission control (VGS) control unit (N15/11n4).
With "circuit 15 OFF" and the vehicle stationary, the selector lever position P or N is engaged as soon as the transmitter key (A8/1) is removed from the electronic ignition lock (EIS) control unit (N73).
| Wiring diagram for intelligent servo module (ISM) control unit | Transmission 722.9 in model 448 | PE27.60-S-2101-97VDA | |
| Transmission 722.9 in model 447.6/7 | PE27.60-S-2101-97VVB | ||
| Transmission 722.9 in model 447.8 | PE27.60-S-2101-97VVA |