Gear lever
Pic. 3.69. gear lever
The shift lever consists of the following components: shift lever position sensor, main switch for transmission modes, shift lock solenoid, shift lever assembly.
The multimodal manual transmission is an electromechanical system in which gear shifting is performed by actuators acting on the command of the electronic control unit of the transmission, in accordance with the position of the shift lever, which is determined by the lever position sensor, and in accordance with the position of the main switch of the transmission modes.
The electromagnetic shift lock mechanism serves to prevent accidental shifting.
Shift lever position sensor and main shift switch
Pic. 3.70. Gear Lever Position Sensor
Pic. 3.71. Sectional shift lever position sensor
The shift lever position sensor consists of a Shift Lever 1 circuit that monitors shift lever positions R, N, E, and M, and a Shift Lever 2 circuit that monitors shift lever positions «+» and «–». There are connectors for these electrical circuits on the shift lever mechanism. Switch contacts (6-pin switch for Lever 1 and 2-pin switch for Lever 2) close and open with longitudinal movements of the gear lever. The electronic control unit of the transmission determines the position of the shift lever by a combination of closed and open switch contacts.
The main transmission mode switch monitors the lateral movement of the shift lever. When the gear lever is set to positions R, N, E, it is turned off, and when set to positions M, «+», «–» - included.
The shift lever position sensor and the main transmission mode switch convert the shift lever movements into electrical signals and transmit them to the electronic control unit of the transmission. The electronic control unit of the gearbox uses these signals to determine the position of the shift lever and actuates the gear shift actuators.
Sport gearshift mode switch
Pic. 3.72. Sport Shift Switch
In automatic shift mode (mode E) the driver can choose one of two switching modes (normal (E) or sports (Es), by pressing the Es switch located on the shift lever trim.
When starting the engine, the gearshift is always set to normal (E).
Shift Lock Mechanism
Pic. 3.73. Block diagram of the shift lock mechanism
The shift lock mechanism is activated in the following situations.
- When the engine is turned off (the switch is moved from the ON position to the OFF position) the mechanism fixes the gear lever in the current position (R, N, E or M). This prevents the shift lever from moving when the engine is off and the shift actuator is not working. This eliminates the possibility of a discrepancy between the position of the gear lever and the actual gear engaged, resulting from accidental movement of the gear lever.
- If the brake pedal is not pressed within 2 seconds and the following three conditions are met at the same time, the mechanism locks the gear lever in the neutral position:
- the gear lever is in the neutral position;
- vehicle speed does not exceed 9 km/h (6 mph);
- the engine is running.
This prevents the vehicle from jerking off as a result of accidental movement of the shift lever.
Turning the engine stop switch to the ON position and depressing the brake pedal will disengage the shift lock mechanism, allowing the shift lever to be moved.
The lock mechanism can be forcibly deactivated with the lock off button.
Gearbox control when starting the car
Pic. 3.74. Block diagram of the control of the gearbox when starting the car from a place
When engaging 1st or 2nd gear (shift lever in position E or M) or reverse (shift lever in R) the electronic control unit of the gearbox partially engages the clutch. In order to prevent the engine from stalling, the transmission electronic control unit sends a signal to the engine electronic control unit for the intelligent electronic throttle control system. This ensures smooth starting of the car without pressing the accelerator pedal. If the driver presses the accelerator pedal in such a situation, the electronic transmission control unit will fully engage the clutch.
To prevent clutch failure, the transmission's ECM will sound a warning signal if the clutch is partially engaged for an extended period of time, as is typical when driving in hilly terrain.
If the gear lever is moved from N to E, M or R at high engine speeds*, the transmission's electronic control unit warns the driver with a buzzer. At the same time, the electronic control unit of the gearbox reduces the speed of the clutch travel (switching speed), preventing the vehicle from jerking away.
* The transmission ECM detects this condition from the signals from the following sensors: transmission input speed sensor, crankshaft position sensor, accelerator pedal position sensor.
Shift control
Pic. 3.75. Shift Control Block Diagram
This transmission has two shift modes: E mode, which shifts gears automatically depending on driving conditions, and M mode, which allows the driver to manually shift gears using the lever without using the clutch. In E mode, the driver can choose between two shift modes by moving the shift lever to the appropriate position: normal mode (E) (better fuel economy than many manual transmission car models) or sport mode (Es) (dynamic sporty driving style).
The electronic transmission control unit shifts gears in accordance with the position of the shift lever and driving conditions using the clutch actuator and gear shift actuator. At the same time, it sends a signal to the engine electronic control unit to turn on the intelligent electronic throttle control system. This achieves smooth gear shifting.
In position M, the gear lever can move in the direction of the signs «+» and «–», commanding the transmission's electronic control unit to shift gears.
When the gear lever is set to position E, the electronic control unit of the gearbox automatically selects the gear that is optimal for driving conditions.
Switching to a higher gear (mode M)
When the driver moves the gear lever from the M position towards the sign «+», the transmission electronic control unit disengages the clutch by controlling the clutch actuator. If the driver depresses the accelerator pedal at this time, the transmission electronic control unit prevents a sudden increase in engine speed by sending a signal to the engine electronic control unit to activate the intelligent electronic throttle control system, which closes the throttle valve.
With the clutch fully disengaged, the transmission's electronic control unit shifts gears by controlling the gearshift actuator.
After changing gear, the electronic control unit of the gearbox engages the clutch.
Downshifting (mode M)
When the driver moves the gear lever from the M position towards the sign «–», the transmission electronic control unit disengages the clutch by controlling the clutch actuator.
In M gearshift mode, the system will automatically downshift depending on vehicle speed according to driving conditions, preventing the engine from stalling.
With the clutch fully disengaged, the transmission's electronic control unit shifts gears by controlling the gearshift actuator. At the same time, it sends a signal to the engine electronic control unit to turn on the intelligent electronic throttle control system.
After changing gear, the electronic control unit of the gearbox engages the clutch.
Automatic upshifting or downshifting (mode E)
When the driver moves the shift lever to position E, the transmission's electronic control unit calculates the optimum gear for the given driving conditions (accelerator pedal position, vehicle speed, etc.), and switches to the desired gear (from 1st to 5th), controlling the clutch actuator, shift actuator and intelligent electronic throttle control system. The actuators and intelligent electronic throttle control during upshifting and downshifting are the same as in M mode.
The electronic control unit of the transmission recognizes the driver's command to accelerate the car from the signal from the accelerator pedal position sensor and provides the required speed, if necessary, downshifting. Thus, even in E mode, the car can accelerate at the request of the driver. In addition, left-hand drive models have a function «kick-down». This function allows the transmission electronic control unit to shift into a lower gear (according to the actual vehicle speed), when the driver presses the accelerator pedal all the way down.
Shift control on climbs and descents (mode E)
The system simplifies driving on winding roads with frequent ups and downs, minimizing gear changes.
Climb shift control
When the electronic control unit of the transmission detects the vehicle is moving uphill, it prohibits upshifting until the uphill is completed. The prohibition is applied before the transmission attempts to upshift or after it has completed downshifting according to the set shift delay.
Downhill shift control
Pic. 3.76. Downhill shift control
When the electronic control unit of the transmission detects the vehicle is going downhill, it shifts to a lower gear (from 5th to 4th) in accordance with the braking signal received when the driver presses the brake pedal. When the transmission electronic control unit detects the vehicle is moving on a steeper descent and a second brake signal is received, it shifts down another gear (from 4th to 3rd).
Ascent or descent recognition
Recognition of the steepness of the ascent or descent is made by comparing the actual acceleration, calculated from the speed sensor signal, and the nominal acceleration value, memorized by the electronic control unit of the gearbox.
DTA function (gearbox control during braking and acceleration)
Pic. 3.77. Block diagram of the DTA function
DTA control function available in both automatic and manual shift modes (modes E and M), acts like this:
During hard acceleration: When the transmission control unit (ECU) detects a sudden depressing of the accelerator pedal to accelerate the vehicle from the position sensor signal, the system shortens the downshift time.
During hard deceleration, the electronic control unit of the transmission detects a sharp release of the accelerator pedal from the signal of the position sensor to reduce the speed of the vehicle. In this case, the system does not allow you to shift to higher gears, thereby providing engine braking and creating a prerequisite for subsequent intensive acceleration of the car.
Gearbox control when the car is stopped
When the shift lever is in E, M, or R and the vehicle speed drops below the set limit*, the transmission's ECM disengages the clutch, preventing the engine from stalling due to reduced RPM.
* Due to the fact that the operation of the electronic transmission control unit is based on the readings of the input shaft speed sensor, the speed limit depends on which gear is engaged.
In addition, when the vehicle is stopped in the E or M shift mode, 1st gear is automatically engaged so that the vehicle can subsequently start off normally. If the vehicle is stopped and the gearshift lever is in position R, automatic gear shifting does not take place.
When the driver's door is opened with the engine running and the gear lever in position E, the transmission's electronic control unit warns the driver with a buzzer located in the instrument panel.
Parking gearbox control
Pic. 3.78. Parking transmission control flow diagram
To park the vehicle, the driver applies the parking brake, shifts the shift lever to E, M, or R, checks that the gear is engaged correctly by checking the warning light, and turns the engine switch to the OFF position. When the engine switch is turned to the OFF position, the selector lock mechanism locks the shift lever. After about 1 s, the electronic control unit of the gearbox engages the clutch. As a result, the parking mode of the gearbox is activated, in which the gears are engaged.
The car can be parked in any position of the gear lever (E, M, R or N). However, when the shift lever is in the N position, the parking mode described above is not possible because the transmission gears are disengaged. In addition, when parking the vehicle in gear, turn the engine switch to the OFF position after the shift indicator lamp indicates position 1 or R.
Approximately 5 seconds after the engine switch is turned to the OFF position, the driver can check which gear is engaged by checking the indicator lamp, which is turned on by the instrument panel electronic control unit.
Diagnostics
If a malfunction is detected, the electronic control unit of the gearbox performs diagnostics and registers the faulty unit or system in memory. In addition, the transmission warning light and the Chk Eng* check engine light alert the driver to malfunctions.
DTCs are stored in the transmission ECM memory (electronic codes). DTCs can be read by the number of flashes of the transmission warning light when the SST scan tool is connected (09843–18040) to the Tc and CC contacts of the DLC3 diagnostic connector. In addition, electronic codes can be read using the microprocessor tester II.
Electronic DTCs cannot be cleared from memory by simply disconnecting the battery terminals. to clear the electronic DTCs, you must connect a smart tester II to the DLC3 diagnostic connector or initialize the transmission electronic control unit using the SST diagnostic tool (09843-18040). Detailed description of the procedure for initializing the electronic control unit of the gearbox.
* When some malfunctions are detected, the check engine lamp Chk Eng lights up.
Table 3.6 lists the new electronic DTCs that the previous models did not have.
Emergency operation
If a malfunction of sensors or actuators is detected, the electronic control unit of the M-MT system goes into emergency mode to reduce the impact of the malfunction on the vehicle's performance.
Adjustment and initialization
After removing and installing parts or assemblies of a multimodal manual transmission, 4 basic maintenance procedures must be performed («clutch preload», «initialization of the electronic control unit of the gearbox», «multimodal manual transmission system learning» and «synchronization positions calibration»).