Function
Function
Controlling the shift solenoids when shifting
Shifting and the lock-up function is controlled by activating the solenoids in a specific pattern. The solenoids S1-S5 determine which gear is to be used and the SLS, SLU and SLT solenoids determine engagement by adjusting 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 the control of torque.
The pressurization of the clutches and the brakes are adjusted by reading the changes of the speed of the transmission input shaft during the shifting process and comparing them to the values calculated in the transmission control module (TCM).
Two shifting patterns can be selected, normal conditions and winter mode (selected using the button).
In normal mode shifting and lock-up occur at relatively low speeds to reduce fuel consumption. In the event of rapid accelerator pedal movements, the transmission control module (TCM) automatically shifts to sport mode.
Shifting patterns
Shifting 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
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. Depending on the gear position, the following combinations can be obtained:
- D The car starts in 3rd gear. Automatic shifting between 3rd, 4th and 5th gears
- 4 The car starts in 3rd gear. Automatic shifting between 3rd and 4th gears occurs earlier than in economy mode, D position. 5th gear is locked out
- 3 The car starts in 3rd gear. There is no upshifting or downshifting
- L The car starts in 2nd gear. There is no upshifting or downshifting.
The warning lamp on the dashboard lights when winter mode is selected.
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 optimal 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.
Adaptation occurs when the following conditions have been met:
- Throttle opening is steady
- Oil temperature between 65° C and 110° C.
Catalytic converter start
Shifting occurs differently during engine warm up. This function is used to help the engine reach its operating temperature by preventing torque converter lock-up and by delaying up shifts. This function works in the D-position but not in the winter mode (W). Because of this function, it is normal for the 1-2 and 2-3 shift to be noticeably delayed when the car engine is cold. This is a normal consequence of this function.
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. If the temperature drops below +20° C the lock-up function will not be used.
Slipping lock-up
The slipping lock-up function provides 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 must be met in order for the function to activate:
- Gear selector in position D, 4 or 3
- Gear 3, 4 or 5
- The transmission input speed is 1100 rpm or more and the throttle opening is 35% or less
- 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) may change the gear shift pattern slightly when driving uphill. This is to avoid busy shifting.
Neutral control (only available on certain models)
This function is activated when the driver stops the car and the car is stationary, at traffic lights for example. The transmission control module (TCM) then disengages the C1 clutch which releases the forward drive of the transmission and reduces the load on the engine. The function improves fuel consumption and reduces vibrations at idle speed. When the driver releases the brake, the C1 clutch engages and drive is resumed.
The following conditions must be met for the Neutral control function to be activated:
- Gear selector in position D, 4, or 3 when Winter mode and Geartronic are not selected
- Oil temperature above + 10° C
- Throttle position < 3%
- Brake pedal depressed
- Speed 0 km/h
- Engine speed < 1500 rpm.
There are two time factors for engagement: There is a 2 second delay in position D when stationary and a 5 second delay at N to D.
Shifting using Geartronic
When the gear selector is moved to the Geartronic position (MAN) the automatic transmission remains in hydraulic position D, but 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 the MAN position. A signal is sent to the gear selector module (GSM) to light the M LED and switches off the other LEDs. The transmission control module (TCM) determines if shifting can be carried out and the driver information module (DIM) indicates the current gear. If shifting is permitted the solenoids are activated according to each specific gear pattern.
However, in certain situations the transmission control module (TCM) assumes the shifting decision. The following 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
- Automatic down shifting occurs 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 then, exceeds 25 km/h. in other cases 2nd gear is retained. For example, when 3rd gear is engaged despite the car being stationary
- Manual up shifting is required after automatic down shifting. Kick-down is not available in the Geartronic-position (MAN)
- The permitted speed for manual down shifting corresponds to those for kick-down downshifting, i.e. engine speed at approximately 6 000 rpm
- If the transmission temperature becomes too high the transmission control module (TCM) determines the shift position. The purpose is to maintain 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 MAN the lever position signal to the gear selector module (GSM) is generated as follows:
For each of the three gear selector positions a hall sensor is mounted on the printed circuit board for the gear selector control module (GSM). A permanent magnet on the 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 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 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 central electronic module (CEM) reads the position of the brake pedal via direct connection to the brake pedal sensor and transmits a signal to the gear selector control module (GSM) to deactivate the solenoid in the gear lever selector. The solenoid lock pin is pushed in and the gear selector lock button can be pressed down as usual to select another gear. When the ignition is in position "0", the solenoid is deactivated. In this position the shifter is mechanically locked by the key lock cable.
Ignition switch interlock
An interlock and security feature (ignition switch interlock) is mechanically connected to the ignition switch by a cable. The ignition switch interlock is controlled by the position of the lock cylinder in the ignition switch and by the position of the gear selector. This means that the gear selector must be in the P-position for the ignition key to be removed from the ignition switch. The ignition key must be turned to position I or II before the lever can be moved from the P-position. The ignition switch interlock is used only in combination with shift-lock.
Park/neutral position (PNP) function
The gear-shift position sensor has a park/neutral position (PNP) function to prevent the engine being started with a gear selected.
This function prevents the engine being started unless the P or N positions are selected. This prevents the car from lurching forwards when started.
For further information, see Design and Function, central electronic module (CEM).
Adaptation data
There are two functions for adaptation in the transmission control module (TCM) software which can be activated:
- Resetting adaptation - carried out after replacing internal components or the entire transmission
- Adaptation function - This function helps the mechanic to adapt the transmission. It 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
- the 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
- Neutral Control engagement and disengagement, if equipped.
While the car is in this mode, the orange/yellow warning lamp in the center of the combined instrument panel is used to indicate when each shift has been adapted to its target value.
When the orange/yellow warning lamp (triangle) flashes after each of the listed shifts, the adaptation is complete.
Note! The function is only available in certain software versions.
Adaptation of the transmission is activated via the VIDA vehicle communication socket.
Counter for transmission fluid 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). If the transmission control module (TCM) detects a permanent fault, an emergency mode is activated. The transmission control module (TCM) then implements corrective action 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 mode
- Limp-home mode.
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.
Emergency mode
The warning lamp in the combined instrument panel comes on and a or text message is displayed for diagnostic trouble codes (DTCs) stored in the transmission control module (TCM).
The transmission shifts in all gears but transmits no signal to the lock-up solenoid. This means that lock-up is not available.
Limp-home mode
The warning lamp in the combined instrument panel comes on or a text message is displayed for diagnostic trouble codes (DTCs) stored in the transmission control module (TCM).
The transmission control module (TCM) interrupts the activation of all solenoids. This means that no shifting is possible. The transmission operates only in 3rd gear in positions 3 and L, 4th gear in position D and reverse in position R. Shifting can only be carried out manually between 3rd and 4th gear and reverse gear.
No control of line pressure solenoids SLS and SLT. Maximum system pressure constantly which results in harsh upshifting and downshifting and harsher shifts when engaging P-R, N-R and N-D.