General System Description
The AW 30-40 is an electronically controlled four gear automatic transmissions. Because the transmission is controlled by an electronic control module gear shifting can be controlled to allow the correct gear to be selected for driving conditions, engine load, driver's wishes, speed, etc. This yields good fuel economy combined with top-class performance and increased comfort by ensuring smoother shifts and lower noise levels.
The control module receives information about the selected gear and driving mode. Together with signals from a number of sensors describing the running conditions of the car, this information is processed by the control module, which calculates optimum shifting and lock-up engagement points, depending on the driving mode selected.
The gear shift is mechanically connected to the transmission by a control rod. The driver can select a driving mode using the driving mode selector located next to the gear shift.
The AW 30-40 automatic transmissions have four gears and torque converter lock-up which is engaged in top gear under normal conditions. In addition to the gear selector there is a mode selector (1) for selecting between three driving modes. The gearshifting and lock-up functions are both controlled by the Transmission Control Module (TCM) (2), which is supplied with signals by the gear-shift position sensor (3) and mode selector.
The TCM also uses information from the engine electronic management system and the speedometer.
The total information flow is processed by the TCM which calculates gear shifting and lock-up engagement points depending on the driving mode selected.
The TCM then controls gear shifting and lock-engagement electronically using the solenoids (S1, S2, SL and STH) built in to the transmission. The solenoids control the transmission hydraulic system in the same way as earlier types of mechanical hydraulically controlled automatic transmissions.
To facilitate fault-tracing, the control module has an On-Board Diagnostic (OBD II) system which records any faults in the control module so that these can be read off using the Data Link Connector (DLC) located at the side of the paring brake (4).
If a serious malfunction occurs in the transmission there are special Emergency Programs which ensure that the car can be driven to the nearest available workshops for repair. At the same time a warning light (5) flashes on the combined instrument panel.
The gear selector mechanism is equipped with an electronic Park/Neutral Position (PNP) switch to prevent accidental engagement of the wrong gear. This prevents the gear selector from being moved out of the P (Park) position unless the foot brake has been depressed and the ignition is switched on.
This function is only available in certain markets.
The mechanical and hydraulic transmission components are enclosed in the torque converter housing (8), the transmission housing (9), rear extension housing (10) and oil pan (11).
The transmission speed sensor (12) in the front transmission housing, temperature sensor (13) in the oil cooler outlet, gear-shift position sensor (5) on the gear selector (14) and the solenoid valves in the control system are connected to three connectors (15).
The gear-shift position sensor incorporates a back-up (reversing) light switch and PNP switch which prevents the engine being started unless the gear shift is in position P or N.
Oil returning from the oil cooler passes to the transmission through inlet (17). The oil cooler is integrated into the engine coolant radiator and cannot be replaced as a separate unit.
The TCM receives information about front planetary train sun wheel speed via a sensor (12) located at the front of the transmission.
The transmission oil level is checked and topped up through the dipstick tube (18).