Function
Function
Controlling the shift solenoids when shifting
The solenoids are activated in a specific pattern to control shifting and the lock-up function. Solenoids S1-S5 determine which gear is to be used. Solenoids SLS, SLU and SLT determine engagement by adjusting the hydraulic line pressure. The basic parameters for the different shifting points are the accelerator pedal (AP) position and the vehicle speed. The shift quality is decided by controlling the torque.
The pressurization of the clutches and the brakes is adjusted by reading the changes in speed of the transmission input shaft during the shifting process and comparing them to the values calculated in the transmission control module (TCM).
Two different shift patterns are available: normal mode and winter mode (selected using the "W" button).
In normal conditions, shifting and lock-up occur at relatively low engine speeds to reduce fuel consumption. In the event of rapid accelerator pedal movements, the transmission control module (TCM) automatically shifts to sport mode.
Gearshift program
Economy mode
When driving at normal acceleration, the transmission control module (TCM) uses a pre-set shifting program, optimized to shift for economy driving. This shifting program is suitable for "normal" driving which provides earlier up shifts and lock-up. In addition the transmission oil pressure is adjusted to provide smooth gear engagement.
Sport mode
The transmission switches from economy mode to sport mode if the accelerator pedal (AP) is pressed down quickly. The conditions are that the throttle opens and the vehicle speed exceeds 50 km/h. As soon as the accelerator pedal (AP) is moved less quickly economy mode is resumed. In the sport mode shifting program the shifting points are adjusted to provide the best possible performance. Down shifting occurs at lower engine speed (RPM).
Extreme mode
At wide open throttle (WOT) the kick-down function is engaged and the transmission shifts to the lowest possible gear. In this way a boost of power is achieved when overtaking for example.
Winter mode (-2007)
Winter mode is selected using the (W) button on the top panel of the gear selector assembly. Winter mode enables starting off in a high gear to prevent the wheels from spinning on a slippery surface. This mode can also be used in other difficult situations in which the driver needs more direct control over gear selection. When D is selected, the car starts in 3rd gear. There is automatic shifting between 3rd, 4th and 5th gears.
When winter mode is selected a W lights on the dashboard.
If kick-down is activated in Winter mode, the transmission uses all gears for maximum performance.
Other modes
Adaptation
The transmission control module (TCM) monitors each shift during all driving conditions to fulfill consistent and smooth shifting. This is carried out by the control module either lowering or increasing the hydraulic line pressure used during the shift itself. The changed pressure levels are stored in the control module memory when the car has been switched off and are retrieved on start-up. This provides improved shifting comfort and increased service life.
Complete adaptation occurs when the following conditions have been met:
- throttle opening is steady
- oil temperature between 65 °C and 110 °C.
Temperature controlled lock-up
If the transmission temperature increases abnormally as a result of heavy load under high ambient temperature conditions, the torque converter lock-up function is activated as often as possible (temperature controlled lock-up). This reduces slippage and the generation of heat in the transmission. The lock-up function will not be used if the temperature drops below +20 °C.
Slipping lock-up
This function ensures smoother engagement with reduced vibration and decreased noise when a gear is engaged. In this mode, the torque converter clutch is engaged, but not fully locked.
The following conditions must be met in order for the function to activate:
- the gear selector in position D or M
- gear 3, 4 or 5
- the transmission input speed is 1100 rpm or more and the throttle opening is 20 - 35% depending on the engine version
- the transmission oil temperature is 40 - 120 °C.
Due to the torque converter slipping between 50-200 rpm, the friction properties of the transmission fluid are very important. The transmission fluid differs from conventional ATF oil properties. Always use the specified fluid for this transmission. Failure to do so may compromise the function and set a diagnostic trouble code (DTC).
The engine coolant must reach a certain temperature before the function engages.
Driving uphill
The Transmission Control Module (TCM) can change the gearshift pattern slightly when driving uphill. This is to avoid close gearshifts.
Alternative driving programs
There are driving programs that are implemented in the transmission but that only are active on certain variants.
Kick-down
When the accelerator pedal is pressed down past a certain point, the Kickdown function is activated. This means that downshifting takes place to get faster acceleration. The pedal position for Kickdown is designated as 110%.
Quick step
Quick step makes the gearshifting function sportier when the driver is more aggressive on the pedal. Lower gears are used for better acceleration.
Fast Off
Fast Off is used to reduce the number of shifts due to heavy traffic in, e.g., city traffic.
The function is activated at fast releases of the accelerator pedal. Even the vehicle's speed, brake pedal, and curve detection affect its function. By keeping a lower gear than normally, unnecessary shifts are avoided. For aborted passing, a lower gear is maintained to be able to take the initiative for future passing.
Gearshifting with Geartronic
When the gear selector is moved to the Geartronic position (M) the automatic transmission remains in hydraulic position D. When the gear selector is moved upwards (+) the gear selector module (GSM) transmits a signal to the transmission control module (TCM) to shift up. When the gear selector is moved downwards (-), a signal is transmitted to the transmission control module (TCM) to shift down. The driver information module (DIM) switches the symbol in the combined instrument panel from D to the current gear, for example 3, when the gear selector is in M mode. The transmission control module (TCM) transmits a signal to the gear selector module (GSM) to light the M LED and switch off the other LEDs. The transmission control module (TCM) determines if the shift can take place. If shifting is permitted the solenoids are activated according to each specific gear pattern.
However, in certain situations the transmission control module (TCM) takes over responsibility for determining shifting. The follow applies:
- When stationary only 1st, 2nd and 3rd gears can be selected. 4th gear can be selected at speeds in excess 30 km/h and 5th at speeds in excess of 40 km/h
- The kick down function is only available in the D position.
- Automatic down shifting occurs for all gears below a certain speed. Example: 2nd gear is selected. Automatic down shifting occurs when shifting from 2nd gear to 1st at 2 km/h if the speed, before this, has exceeded 25 km/h. Otherwise 2nd gear is maintained. For example, there may be situations when 2nd or 3rd gear is engaged despite the car being stationary. Manual up shifting is required after automatic down shifting
- The permitted engine speeds for manual down shifting corresponds to those for kick-down up shifting, i.e. engine speeds of approximately 6,000 rpm
- If transmission temperature becomes too high then the Transmission Control Module (TCM) takes over the gearshift decisions. The purpose of this is to engage a gear where lock-up is possible at the current speed.
- Lock-up is possible in 3rd, 4th and 5th gears. (1st and 2nd gears do not have lock-up).
Other
In position M, the signal indicating the position of the lever to the gear selector module (GSM) is generated as follows: For each of the three gear selector positions there is a Hall sensor on the printed circuit board for the gear selector control module (GSM). A permanent magnet on the cover in the gear selector lever affects the output signals from the sensors to the control module. The control module can read off the position of the lever through the differences in the signal characteristics.
Shift-lock
To avoid any chance of the gear selector inadvertently moving from the P or N position, the car is also equipped with an electrically operated shift-lock function. This locks the interlock pin in the gear selector lever in the shift-lock section, locking the selector lever in the P- or N position.
From P to another gear position
To move the gear selector from the P position, the ignition must be switched on and the brake pedal depressed. (The stop lamp switch is activated.). The transmission control module (TCM) retrieves the brake pedal position via the CAN network and the currently selected gear from the internal gear-shift position sensor. The signal is then transmitted from the transmission control module (TCM) to the gear selector module (GSM) to control the solenoid (electro magnet) in the gear selector assembly. When the gear selector is in position P, the solenoid is activated and the lock pin slides in. The gear selector lock button can be pressed down as usual to select another gear. There is a Hall sensor in the gear selector assembly which is affected by a permanent magnet on the cover of the assembly. The Hall sensor is deactivated when the gear selector is moved from position P. The shift-lock solenoid is disengaged at the same time. This prevents the gear selector from sticking in position N. When the ignition is in position "I" or "0" the solenoid is deactivated. The gear selector is mechanically locked in position P by breaking the power supply to the solenoid.
From N to another gear position
To move the gear selector from the N position, the ignition must be switched on and the brake pedal depressed. (The stop lamp switch is activated.). The transmission control module (TCM) retrieves the brake pedal position via the CAN network and the currently selected gear from the internal gear-shift position sensor. The signal is then transmitted from the transmission control module (TCM) to the gear selector module (GSM) to control the solenoid (electro magnet) in the gear selector assembly.
With the gear selector in N the solenoid deactivates and the lock pin is drawn in and the gear selector can be shifted to position D and M normally. However the lock button on the gear selector must be pressed before R or P can be selected. When the ignition is in position "I" or "0", the solenoid is deactivated.
Shift-lock override
The mechanical lock mechanism in the gear selector assembly can be overridden so that the gear selector can be moved when the power is off or in the event of an electrical fault. A small tool can be inserted under a cover on the gear selector assembly panel to release the gear selector.
Park / neutral position (PNP) function
The car has a park/neutral position (PNP) function to prevent the starter motor from turning when a gear is selected. This function is controlled by the transmission control module (TCM), which receives a signal from the gear selector module (GSM) indicating that the gear selector is in position P or N. The park / neutral position (PNP) function ensures that the starter motor can only be activated when the gear selector is in position P- or N. This prevents the car from lurching forwards when started.
Adaptation data
There are two functions for adaptation in the transmission control module (TCM) software which can be activated:
- Resetting adaptation - should be performed after replacing an internal component or the whole transmission.
- Adaptation function - This function helps the mechanic to adapt the transmission. This makes it easier to reset the function of the transmission after repair or replacement of, for example:
- the transmission control system
- the transmission fluid
- the entire transmission
- transmission control module (TCM).
When the adaptation function has been activated, the test drive instructions must be followed. The following shifts can be adapted:
- 1-2
- 2-3
- 3-4
- 4-5
- N-D
- 5-4
- 4-3
- 3-2
- 2-1
- N-R.
While the function is activated, the general warning lamp in the combined instrument panel indicates when each shift has been adapted to its target value.
When the general warning lamp (triangle) flashes after each shift, the adaptation is complete.
Adaptation of the transmission is activated via the VIDA vehicle communication socket.
Gauge for transmission oil data
A counter for transmission oil quality is built into the software for the transmission control module (TCM). The counter counts up the amount of time the oil is above a certain temperature. When the counter has reached the maximum value, the diagnostic trouble code (DTC) for an oil change is stored in the control module. When replacing transmission fluid, the counter must be reset to prevent a diagnostic trouble code (DTC) being stored incorrectly. This applies when the transmission fluid is changed and when the fluid is changed during a repair.
The reset function is activated via the VIDA vehicle communication socket.
Emergency mode in the event of a fault
An emergency program is activated to deal with the fault when the transmission control module (TCM) detects a transmission fault (permanent fault). The transmission control module (TCM) then implements certain corrective actions to protect the transmission, while leaving the car in the best possible drivable condition. Minor malfunctions do not activate an emergency program. There are different programs depending on the type of fault.
- Emergency/limp-home mode
- Fail-safe action (temporary action)
The fail-safe action is indicated as soon as the fault is detected. Normal function is resumed if the fault disappears. Emergency mode is activated for minor faults and the Limp home mode for the most serious faults. If the malfunction is intermittent, the transmission control module (TCM) returns to normal operation the next time the ignition is switched on.
The warning lamp in the combined instrument panel lights and a text message appears in the display in the combined instrument panel if emergency/limp home mode is engaged. No text is displayed until the fault has been detected when the ignition is switched on.