AUTOMATIC TRANSAXLE SYSTEM


  1. FUNCTION OF MAIN COMPONENTS

    Component Function
    ATF Cooler (Oil Cooler Assembly) Cools down the ATF.
    Torque Converter Assembly

    • Transmits engine power to the transaxle.

    • Increases engine torque.
    Oil Pump Assembly Provides oil pressure necessary for the transaxle operation.
    No. 1 Clutch (C1) Connects the intermediate shaft and the Ravigneaux planetary rear sun gear.
    No. 2 Clutch (C2) Connects the intermediate shaft and the Ravigneaux planetary ring gear.
    No. 1 Brake (B1) Prevents the Ravigneaux planetary front sun gear and the underdrive planetary carrier from turningclockwise or counterclockwise.
    No. 2 Brake (B2) Prevents the Ravigneaux planetary ring gear from turning clockwise or counterclockwise.
    No. 3 Brake (B3) Prevents the underdrive planetary ring gear from turning clockwise or counterclockwise.
    No. 1 1-way Clutch (F1) Prevents the Ravigneaux planetary ring gear from turning counterclockwise.
    Planetary Gears Change the route through which driving force is transmitted in accordance with the operation of each clutch and brake in order to increase or reduce the input and output speed.
    Shift Solenoid Valve SL1 Controls the No. 1 clutch (C1) pressure.
    Shift Solenoid Valve SL2 Controls the No. 2 clutch (C2) pressure.
    Shift Solenoid Valve SL3 Controls the No. 1 brake (B1) pressure.
    Shift Solenoid Valve SL4 Controls the No. 3 brake (B3) pressure.
    Shift Solenoid Valve SLU

    • Controls the lock-up clutch pressure.

    • Controls the No. 2 brake (B2) pressure.
    Shift Solenoid Valve SLT Controls line pressure.
    Shift Solenoid Valve SL

    • Switches the lock-up relay valve.

    • Switches the B2 apply control valve and the reverse sequence valve.
    Counter Gear Speed Sensor Detects the speed of the counter gear.
    Input Turbine Speed Sensor Detects the input speed of the transaxle.
    ATF Temperature Sensor Detects the ATF temperature.
    ATF Pressure Switch Monitors the output fluid pressure of the shift solenoid valve.
    Park/Neutral Position Switch Assembly Detects the shift lever position.
    Transmission Control Switch

    • Detects that the shift lever is in M.

    • Detects the driver's upshift and downshift operations when the shift lever is in M.
    Combination Switch Assembly Sport Mode Switch Turns the Sport mode on and off.
    ECO Mode Switch Turns the ECO mode on and off.
    TCM

    • Controls each shift solenoid valve in response to a signal from each sensor and switch.

    • Makes a diagnosis and memorizes the failed section when the TCM detects a malfunction.
    ECM Controls engine output in response to a signal from the TCM.
    Air Conditioning Amplifier Assembly

    • Transmits the operating state of the air conditioning system to the ECM.

    • Outputs the ECO mode signal to the ECM.
    Driving Support ECU Assembly*1 Sends the information about the operation conditions of the dynamic radar cruise control system to the ECM.
    Combination Meter Assembly Shift Position and Gear Range Indicator Indicates the shift position.
    Gear Shift Indicator*2 Illuminates to promote upshifting when the vehicle is being driven with the shift lever in M.
    Sport Mode Indicator Light*3 Illuminates when Sport mode is active.
    ECO Mode Indicator Light*3 Illuminates when ECO mode is active.
    MIL Illuminates or blinks to inform the driver when the ECM detects a malfunction.
    ATF Temperature Warning Light*3 Warns the driver by lighting up when the ATF is at a high temperature.
    Master Warning Light*4 Warns the driver by lighting up when a message is shown on the multi-information display.
    Multi-information Display*4

    • Displays that Sport or ECO mode is active.

    • Warns the driver by displaying a message when the ATF is at a high temperature.
    Buzzer

    • Sounds when the downshift operation is rejected.

    • Warns the driver by sounding when a message is shown on the multi-information display.

    • *1: Models with dynamic radar cruise control system

    • *2: Models with Gear Shift Indicator

    • *3: Models with analog type combination meter assembly

    • *4: Models with Optitron type combination meter assembly

  2. SYSTEM CONTROL

    Electronic Control of Automatic Transaxle
    Control Outline
    Shift Timing Control The TCM sends current to shift solenoid valves SL1, SL2, SL3, SL4, SL and/or SLU based on signals from various sensors in order to shift the gears.
    Clutch to Clutch Pressure Control Controls the pressure applied directly to the No. 1 Clutch (C1), No. 2 Clutch (C2), No. 1 Brake (B1) and No. 3 Brake (B3) by actuating the shift solenoid valves (SL1, SL2, SL3 and SL4) in accordance with TCM signals.
    Line Pressure Optimal Control Actuates the shift solenoid valve SLT to control the line pressure in accordance with information from the TCM and the operating conditions of the transaxle.
    Powertrain Cooperative Control Performs both shift control and engine output control in an integrated way, achieving excellent shift characteristics and driveability.
    Artificial Intelligence-shift Control (AI-shift Control) Based on the signals from various sensors, the TCM determines the road conditions and the intention of the driver. Thus, an appropriate shift pattern is automatically determined, improving driveability.
    Deceleration Downshift Control To prevent engine speed from decreasing and thereby maintain the fuel cut, the TCM performs downshifts before the fuel cut ends.
    Lock-up Timing Control The TCM sends current to the shift solenoid valves SL and SLU based on signals from various sensors to engage or disengage the lock-up clutch.
    Flex Lock-up Clutch Control Controls the shift solenoid valve SLU, provides an intermediate mode between the on and off states of the lock-up clutch, and increases the operating range of the lock-up clutch to improve fuel economy.
    Multi-mode Automatic Transmission The TCM appropriately controls the automatic transaxle in accordance with the gear range selected using the shift lever while the shift lever is in M.
    Gear Hold Control Maintains the gear range selected by the driver unless the vehicle is decelerated and the shift lever is operated.
    Complete Lock-up Control Transmits engine output directly to the transaxle using the torque converter lock-up clutch when in 2nd gear or higher. However, even in 2nd gear or higher, when engine speed is low, the control is not operated.
    High Response Upshift Control Achieves a crisp and high response upshift using the clutch to clutch pressure control and powertrain cooperative control.
    Blipping Downshift Control Achieves smooth and quick downshift using clutch to clutch pressure control and powertrain cooperative control.

    1. Clutch to Clutch Pressure Control


      • Clutch to clutch pressure control is used for shift control. As a result, shift control in 2nd gear or above can be performed without using a 1-way clutch, making the automatic transaxle lightweight and compact.

      • Based on the information about transaxle input and output speed, engine torque and other items, the TCM controls each clutch and brake in accordance with the optimum fluid pressure and timing, in order to shift the gears. The TCM changes gears using fluid pressure circuits which enable the No. 1 clutch (C1), No. 2 clutch (C2), No. 1 brake (B1) and No. 3 brake (B3) to be controlled independently, and using the high flow SL1, SL2, SL3 and SL4 shift solenoid valves which directly control the line pressure. As a result, highly responsive and excellent shift characteristics have been achieved.

        A01V2FME01

    2. Line Pressure Optimal Control


      • The line pressure is controlled using shift solenoid valve SLT.

      • Through the use of shift solenoid valve SLT, the line pressure is optimally controlled in accordance with the engine torque information, as well as with the internal operating conditions of the torque converter and the transaxle.

      • Accordingly, the line pressure can be accurately controlled in accordance with the engine output, traveling condition and the ATF temperature, thus achieving smooth shift characteristics and regulating the workload of the oil pump (reducing unnecessary parasitic losses).

        A01V28TE01

    3. Powertrain Cooperative Control


      1. Throttle Control at Starting


        • The engine output is optimally controlled using the fuel injection volume control in real time and in accordance with the transient force from the torque converter when the vehicle is launched. This achieves a suppressed sense of lurching forward, tire slippage suppression and improved responsiveness, ensuring excellent launch performance.

          A01V2ANE01

      2. Deceleration Force Control


        • The TCM determines the gear that is to be selected when the accelerator pedal is released (released completely) in accordance with the way the accelerator pedal is released (suddenly or slowly) during deceleration. In this way, unnecessary upshifts are prevented during deceleration, matching the driver's intentions. In addition, unintended downshifts are prevented when accelerating the vehicle again, achieving smooth acceleration.

          A01V29WE01

      3. Transient Shifting Control


        • Quick response and shift shock reduction have been achieved through cooperative control with the following controls:


          1. Fuel injection volume control

          2. Electronic control of the speed of the hydraulic pressures to engage and release the clutch and brake

            A01V2BAE01

    4. Artificial Intelligence Shift Control (AI-shift Control)


      • The automatic transaxle gear is determined by the shift pattern, which uses the vehicle speed and accelerator pedal depression angle.

      • Additionally, AI-shift control enables the TCM to estimate the road conditions and the driver's intention in order to automatically control the shift pattern in an optimal manner. As a result, a comfortable ride has been achieved.

      • AI-shift control includes road condition support control and driver's intention support control.

      • AI-shift control determines optimal transaxle control based on input signals and automatically changes the shift pattern.

        A01V2GXE01

      1. Road Condition Support Control


        • Under road condition support control, the TCM determines from the accelerator pedal depressing angle and the vehicle speed whether the vehicle is being driven uphill or downhill. To achieve the optimal drive force while driving uphill, this control prevents unnecessary upshifts. To achieve the optimal engine brake effect while driving downhill, this control automatically performs downshifts.

          A01V2C8E01

      2. Driver's Intention Support Control


        • The driver's intention is estimated based on the accelerator pedal depression angle and vehicle condition to switch to a shift pattern that is well-suited to the driver.

    5. Deceleration Downshift Control


      • The TCM performs downshift control to help prevent the engine speed from decreasing, thus keeping fuel cut control operating for as long as possible. In this way, fuel economy is improved.

      • When the vehicle is in 6th gear and starts decelerating, the transaxle downshifts from 6th to 5th, 5th to 4th and 4th to 3rd before fuel cut control ends so that the fuel cut control can continue operating.

        A01V2ABE07

    6. Lock-up Timing Control


      • The TCM uses lock-up timing control in order to improve fuel consumption performance in 2nd or higher when the shift lever is in D or M.

        A01V2AHE02
      Lock-up Timing Control Operation
      Gear Position Shift Lever Position
      D M
      1st X X
      2nd ○ ○
      3rd ○ ○
      4th ○ ○
      5th ○ ○
      6th ○ ○

      Tech Tips

      ○: Available

      X: Not available

    7. Flex Lock-up Clutch Control


      • During acceleration, partial control of the power transmission between the lock-up clutch and torque converter greatly boosts transmission efficiency in accordance with the driving conditions, improving fuel economy.

      • Even when the vehicle is decelerating (the accelerator pedal is released), flex lock-up clutch control operates. As a result, the fuel-cut area is expanded and fuel economy is improved.

      • By allowing flex lock-up clutch control to continue operating during gearshifts, smooth torque transmission is obtained. As a result, fuel economy and driveability are improved.

      • For flex lock-up clutch control, H infinity (H∞) control theory is used to achieve a high level of system stability and response to various characteristic changes.

        A01V2EEE01
        A01V2C7E02
      Flex Lock-up Clutch Control Operation
      Gear Position Shift Lever Position
      D
      1st X
      2nd ○
      3rd ○*1
      4th ○*2
      5th ○*2
      6th ○*2

      Tech Tips

      ○: Available

      X: Not available

      -: Not applicable

      *1: Flex lock-up clutch control operates during deceleration only via coast downshift from 4th gear with deceleration flex lock-up.

      *2: Flex lock-up clutch control also operates during deceleration.

    8. Multi-mode Automatic Transmission


      • The multi-mode automatic transmission is designed to allow the driver to switch the gear ranges. After moving the shift lever to M, the driver can select the desired gear ranges by moving the shift lever to "+" (forward) or "-" (backward). Thus, the driver is able to shift gears with a manual-like feel.

        A01V28ME01

      • When the vehicle is being driven at a speed that is higher than the maximum safe speed for a downshift, any attempt to shift to a lower range by operating the downshift will not be executed in order to protect the automatic transaxle. In this case, the ECM sounds the buzzer in the combination meter assembly twice to alert the driver.

      • When the shift lever is in M, gear hold control, complete lock-up control, high response upshift control and blipping downshift control are used in order to improve response in accordance with the driver's operation of the accelerator pedal, shift lever, and to improve gear shift feeling.

      A01V2EIE02

    9. Gear Hold Control


      • Gear shifting will not be performed under gear hold control as long as the shift lever is not operated. This makes it possible to make efficient use of the highest engine speeds. However, if the vehicle speed drops, a downshift will be performed from the current gear to a gear appropriate for that speed. Also, when the ATF temperature is extremely high, an upshift will be performed automatically.

    10. High Response Upshift Control


      • The high response upshift control achieves highly responsive upshift operation using clutch to clutch pressure control, which regulates each clutch and brake quickly and precisely, and by using the powertrain cooperative control, which optimally regulates engine torque during shifting.

        A01V2D3E02

    11. Blipping Downshift Control


      • The blipping downshift control regulates each clutch and brake using the clutch to clutch pressure control, allowing them to be engaged smoothly and disengaged quickly. In addition, fuel injection volume is increased and engine speed is boosted by the powertrain cooperative control, thus ensuring proper engine brake force. In this way, a smooth and quick downshift is achieved.

        A01V2CBE02

  3. FUNCTION


    1. Shift Pattern Select System


      1. The driver can select 2 different settings for the shift schedule and AI-shift control.

      2. When the pattern select switch is on (Sport mode), a more aggressive shift schedule and AI-shift tuning are selected for sporty driving.

        A01V2AME02
        *1 Normal Mode Shift Pattern
        *2 Accelerator Pedal Depressing Angle
        *3 Vehicle Speed
        *4 Sport Mode Shift Pattern

    2. Gear Shift Indicator System


      1. Gear Shift Indicator system is a system to promote upshifting to the fuel-efficient and optimal gear ranges in accordance with the driving conditions such as the accelerator pedal opening and the vehicle speed, etc. when the vehicle is running while the shift lever is in M.

      2. By driving in accordance with the upshifting recommendations indicated by the Gear Shift Indicator in the combination meter assembly, the driver can enhance environmental performance, improve fuel economy and reduce exhaust gas output within the limits of engine performance.

        A01V2F7E01

  4. FAIL-SAFE


    1. The fail-safe function minimizes the loss of operability when an abnormality occurs in a sensor or a shift solenoid valve.

    2. For details, refer to the Repair Manual.

  5. DIAGNOSIS


    1. When the TCM detects a malfunction, the TCM records the malfunction and memorizes the information related to the fault. Furthermore, the TCM illuminates or blinks the MIL in the combination meter to inform the driver.

    2. The TCM will also store the Diagnostic Trouble Codes (DTCs) of the malfunctions. The DTCs stored in the TCM are output to the Global TechStream (GTS) via the ECM and the DLC3.

    3. For details, refer to the Repair Manual.