Design

Design

Control module




The Transmission Control Module (TCM) is integrated with the gear position indicator as one unit. The unit is fitted in the top side of the transmission housing, on the gear selector shaft. The control module's connector is directly connected to the transmission.

Gear position indicator
The gear position indicator is integrated with the Transmission Control Module (TCM) as one unit.
The gear position indicator informs the Transmission Control Module (TCM) on the gear selected, and whether reverse gear is engaged to light the reversing lamp. The gear position indicator contains a permanent magnet and a linear Hall sensor. The gear position indicator creates a signal voltage of between 0 and 5 V which equates to current gear selector lever position.
The gear position indicator can be diagnosed.

Voltage level for the different gear positions
P approximately 0,65 V
R approximately 1,64 V
N approximately 2,12 V
D approximately 2,49 V

Solenoid S1 and S2




The solenoids S1 and S S2 are located in the transmission control system, which is fitted on the front edge of the transmission. The solenoids are the on/off type and consist of an electrical coil that controls a hydraulic valve. The solenoids are supplied 12 V via the transmission control module (TCM) and are grounded in the control system. The solenoids control shifting and the transmission control module (TCM) activates the solenoids with engine braking for 1st gear.
The solenoids can be diagnosed.

Lock-up solenoid, SLU




The lock-up solenoid ( SLU) is located on the transmission control system, which is fitted on the front edge of the transmission. The lock-up solenoid ( SLU) consists of an electrical coil that controls a hydraulic valve. The solenoid is controlled with a pulse width modulated (PWM) voltage and is grounded via the transmission control module (TCM). The control module regulates the lock-up engagement of the torque converter. During lock-up, the solenoid is pulsed in, which makes lock-up engagement gentle. The solenoid allows the torque converter to work in one of three modes: "open", "controlled slippage" and "locked". The solenoid has a linear hydraulic function.
The solenoid can be diagnosed.

Linear pressure solenoid, SLT




The linear pressure solenoid, SLT, is located in the transmission control system, which is fitted on the front edge of the transmission. The linear pressure solenoid, SLT, consists of an electrical coil that controls a hydraulic valve. The solenoid is controlled with a pulse width modulated (PWM) voltage and is grounded via the transmission control module (TCM). The solenoid has a linear hydraulic function. The hydraulic valve is controlled by the varying current resulting from the current pulse ratio. With a high pulse ratio, i.e. high current strength (approx. 1 A), the system pressure is low. With a low pulse ratio, i.e. low current strength, the system pressure is high. In the event of an open circuit the system pressure is at a maximum, resulting in hard shifting. The hydraulic valve is then fully open.
The solenoid can be diagnosed.

Linear pressure solenoid SLC1, SLC2, SLC3 and SLB1




The linear pressure solenoids SLC1, SLC2, SLC3 and SLB1 are located in the transmission control system, which is fitted on the front edge of the transmission. The designation of the solenoid is linked to the component (clutch/brake band) that the solenoid controls. The linear pressure solenoids consist of an electrical coil that controls a hydraulic valve. The solenoids are controlled with a pulse width modulated (PWM) voltage and are grounded via the transmission control module (TCM). The solenoids have a linear hydraulic function. The hydraulic valves are controlled by the varying current resulting from the current pulse ratio. With a high pulse ratio, i.e. high current strength (approx. 1 A), the system pressure is low. With a low pulse ratio, i.e. low current strength, the system pressure is high. In the event of an open circuit the system pressure is at a maximum, resulting in hard shifting. Here, the hydraulic valve is fully open.
The solenoids can be diagnosed.

Speed sensor, input shaft




The speed sensor for the input shaft is located inside the gearbox. The sensor is a so-called "active sensor" (Hall sensor) and is supplied with 12 V power. When the pulse wheel on clutch C2 rotates the sensor generates a pulsed current (square wave), where the strength of the current depends on the position of the pulse wheel. The signals from the coil in the sensor are then acted on by magnetic-sensitive resistance, which means that the output signal is a current which fluctuates between 7 mA and 14 mA, and whose frequency increases with speed. The Transmission Control Module (TCM) calculates transmission speed using the signal from the sensor.
The Transmission Control Module (TCM) uses information on input shaft speed for:
- calculating how much torque reduction shall be requested from the Engine Control Module (ECM) with gearshifting
- comparing engine speed with input shaft speed to calculate the slipping speed of the torque converter
- calculating gearshift timing
- calculating engagement and disengagement of the lock-up function
- comparing the signal with the signal from the transmission speed sensor for the output shaft, for calculating the current gear ratio. This is performed to identify whether the value corresponds with the expected gear ratio.
The speed sensor for the input shaft can be diagnosed.

Speed sensor, output shaft




The speed sensor for the output shaft is located inside the gearbox. The sensor provides a signal to the Transmission Control Module (TCM) on vehicle speed. The sensor is a so-called "active sensor" (Hall sensor) and is supplied with 12 V power. When the pulse wheel rotates (the wheel for shiftlock), the sensor generates a pulsed current (square wave), where the strength of the current depends on the position of the pulse wheel. The signals from the coil in the sensor are then acted on by magnetic-sensitive resistance, which means that the output signal is a current which fluctuates between 7 mA and 14 mA, and whose frequency increases with speed. The Transmission Control Module (TCM) uses information on output shaft speed for:
- calculating how much torque reduction shall be requested from the Engine Control Module (ECM) with gearshifting
- comparing engine speed with output shaft speed to calculate the slipping speed of the torque converter
- calculating gearshift timing
- calculating engagement and disengagement of the lock-up function
- comparing the signal with the signal from the transmission speed sensor for the input shaft, for calculating the current gear ratio. This is performed to identify whether the value corresponds with the expected gear ratio.
The speed sensor for the output shaft can be diagnosed.

Oil temperature sensor




The temperature sensor is the NTC type. The temperature sensor is located on the transmission control system inside the side cover and measures the temperature of the transmission oil in the sump. The temperature sensor is an integrated part of the cable harness. The temperature sensor is supplied with 5 V and is grounded via the Transmission Control Module (TCM). By measuring the voltage drop over the sensor's NTC resistor the control module can determine the temperature of the transmission oil. The Transmission Control Module (TCM) uses the information on transmission oil temperature for:
- calculating transmission gearshift timing
- calculating engagement and disengagement of the lock-up function.
The Transmission Control Module (TCM) stores the time for which the temperature has been within a certain temperature range and if a certain temperature and time has been exceeded, then a diagnostic trouble codes (DTC) is generated to indicated that an oil change is necessary.
The temperature sensor can be diagnosed.

Gear Selector Module (GSM)




The gear selector assembly is located in the tunnel console and is mechanically connected to the transmission by a cable which moves the shuttle valve in the transmission control system. The Gear Selector Module (GSM) is located on the top panel of the gear selector assembly. The Gear Selector Module (GSM) is supplied with power from the Central Electronic Module (CEM). The Gear Selector Module (GSM) communicates with the Transmission Control Module (TCM) via serial communication, to light up gear position indication amongst other things. Gear position indication consists of a row of LEDs in the top panel of the gear selector assembly.
The Central Electronic module (CEM) has a cable which is directly connected to the Gear Selector Module (GSM) to control the shiftlock solenoid. The supply of power and ground for the solenoid are directly connected to the Gear Selector Module (GSM).
The switch for winter program (W) is located on the top panel of the gear selector assembly. Upon activation the switch sends a request to activate the winter program (Winter mode) to the Transmission Control Module (TCM). The Transmission Control Module (TCM) then determines whether or not the winter program is possible.
The Gear Selector Module (GSM) can be diagnosed. In the event of a fault a signal on fault status is sent to the Transmission Control Module (TCM) which then stores any diagnostic trouble codes (DTC).

Shiftlock




To prevent the gear selector from being unintentionally shifted out of P, the vehicle is equipped with an electronic shiftlock. This blocks the gear selector lever's retaining pin in the lock segment, holding the gear selector in the P position. The gear selector can only be moved from P to another gear position when the ignition is on (key position II) and the brake pedal is depressed (brake light switch actuated). The central electronic module (CEM) detects the brake pedal position via a direct connection to the brake pedal sensor. It then sends a signal to the gear selector module (GSM) to deactivate the electromagnetic solenoid in the gear selector assembly. The solenoid lock pin is pulled in and it is possible to depress the catch in the gear selector lever to select another gear. If the ignition key is in "0", the solenoid is deactivated. In this position, the gear selector is manually locked via the keylock function.

Keylock




A lock and safety function (keylock) is mechanically linked to the ignition switch by a cable. The keylock is controlled by the lock piston position in the ignition switch and by the gear selector lever position. This means that the ignition key can only be removed from the ignition switch if the gear selector lever is in P. This also means that the gear selector lever can only be moved from P if the ignition key has been turned to position I. The keylock is only available in combination with shiftlock. In order to prevent the gear selector from moving, the central electronic module (CEM) electrically locks the shiftlock solenoid between key positions I and II since the transmission control module (TCM) is not supplied power until key position II.

Gear selector assembly

Gear selector assembly with Geartronic function




The gear selector assembly of Geartronic has a unique design and function. In addition to the lever positions P/R/N/D it also has a mode for "manual" (MAN) shifting.

The gear selector lever for Geartronic has the following functions:
- P: Park.
- R: Reverse.
- N: Neutral
- D: Automatic shifting between all gears (unless Winter mode is engaged ( W)). For more information, see Function/ Shift program/ Winter mode.
- MAN: Manual shifting. Three Hall sensors are fitted on the gear selector module (GSM). A permanent magnet on the gear selector lever acts on the sensor output signals to the gear selector module (GSM)