AUTOMATIC TRANSMISSION SYSTEM DETAILS


  1. FUNCTION OF MAIN COMPONENTS

    Component Function
    Torque Converter Clutch Assembly

    • Transmits the engine power to the transmission.

    • Increases engine torque.
    Oil Pump Provides oil pressure necessary for the transmission operation.

    Overdrive Direct Clutch (C0)

    		 Connects the overdrive planetary sun gear and the overdrive planetary carrier.

    Forward Clutch (C1)

    		 Connects the input shaft and the front planetary ring gear.

    Direct Clutch (C2)

    		 Connects the input shaft and the front and rear planetary sun gear.

    Overdrive Brake (B0)

    		 Prevents the overdrive planetary sun gear from turning either clockwise or counterclockwise.

    2nd Coast Brake (B1)

    		 Prevents the front and rear sun gear from turning either clockwise or counterclockwise.

    2nd Brake (B2)

    Prevents the outer race of F1from turning either clockwise or counterclockwise, thus preventing the front and rear sun gear from turning counterclockwise.

    1st and Reverse Brake (B3)

    		 Prevents the rear planetary carrier from turning either clockwise or counterclockwise.

    Overdrive 1-way Clutch (F0)

    		 Connects the overdrive planetary sun gear and the planetary carrier when engine power is transmitted to the overdrive input shaft.

    1-way Clutch Assembly (F1)

    Prevents the front and rear planetary sun gear from turning counterclockwise when B2is operating.

    No. 2 1-way Clutch (F2)

    		 Prevents the rear planetary carrier from turning counterclockwise.
    Planetary Gears Change power transmission route in accordance with clutch and brake operation, and increase or decrease output shaft revolutions accordingly.
    Transmission Solenoid Assembly (S1 and S2) Switch the shift valves.
    Line Pressure Control Solenoid Assembly (SLT) Controls line pressure.
    Shift Control Solenoid Assembly (SLU) Controls the lock-up clutch.
    ATF Temperature Sensors Detects the ATF temperature.
    Input Speed Sensor (NC0) Detects the input speed of the transmission.
    Output Speed Sensor (SP2) Detects the output speed of the transmission.
    Park/Neutral Position Switch Assembly Detects the shift lever position (P, R, N, D, 2, L).
    Shift Lock Control ECU Sub-assembly Transmission Control Switch Detects that the shift lever is in 3.
    2nd Start Switch (Pattern Select Switch Assembly)*1 Switches the 2nd start mode.
    ECM

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

    • When the ECM detects a malfunction, the ECM makes a diagnosis and memorizes the failed section.
    4WD Control ECU Sends a drive mode signal to the ECM.
    Air Conditioning Amplifier Assembly Sends a shift-up tardiness control signal to the ECM.
    Driving Support Switch Control ECU*2 Sends a 2nd start mode signal to the ECM.
    Combination Meter Assembly Shift Display Indicates the shift lever position.
    MIL Illuminates or blinks to inform the driver when the ECM detects a malfunction.
    2nd Start Indicator Light Illuminates when the driver selects the 2nd start mode.
    ATF Temperature Warning Light*1 Warns the driver by lighting up when the ATF is at a high temperature.
    Multi-information Display*2

    • Displays the 2nd start mode select.

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

    • Displays a Diagnostic Trouble Code (DTC).
    Master Warning Light*2 Warns the driver by lighting up when a message is shown on the multi-information display.
    Multi Buzzer*2 Warns the driver by sounding when a message is shown on the multi-information display.
    DLC3 The Diagnostic Trouble Codes (DTCs) can be read by connecting an Global TechStream (GTS).

    • *1: Models with analog display type combination meter assembly

    • *2: Models with Optitron display type combination meter assembly

  2. SYSTEM CONTROL

    Electronic Control of Automatic Transmission
    Control Function
    Shift Timing Control The ECM sends current to the shift solenoid valves S1 and/or S2 based on signals from various sensors in order to shift the gears.
    Line Pressure Control Actuates the shift solenoid valve SLT to control the line pressure in accordance with information from the ECM and the operating conditions of the transmission.
    Clutch Pressure Optimal Control The shift solenoid valve SLT minutely controls the clutch pressure in accordance with the engine output and driving conditions of the transmission.
    Engine Torque Control Retards the engine ignition timing temporarily to improve shift feeling while upshifts or downshifts occur.
    N to D Squat Control When the shift lever is moved from N to D, the gear is temporarily engaged to the 2nd and then to the 1st to reduce vehicle squat.
    Lock-up Timing Control The ECM sends current to the shift solenoid valve SLU based on signals from various sensors and engages or disengages the lock-up clutch.
    Flex Lock-up Clutch Control Controls the shift solenoid valve SLU, provides an intermediate mode for when the lock-up clutch is between on and off, and increases the operating range of the lock-up clutch to improve fuel economy.
    Artificial Intelligence-shift Control (AI-shift Control) Based on the signals from various sensors, the ECM determines the road conditions and the intention of the driver. Then, an appropriate shift pattern is automatically determined, thus improving driveability.

    1. Line Pressure Control


      1. In order to obtain a predetermined line pressure characteristic in accordance with each sensor signal, the ECM activates the shift solenoid valve SLT to regulate the throttle pressure.

      2. This makes it possible for the primary regulator valve to precisely and minutely control the line pressure in accordance with the engine output, thus providing smoother shift characteristics.

        A01DLGRE02

    2. Clutch Pressure Optimal Control


      1. The ECM monitors the signals from various types of sensors, such as the input speed sensor, allowing shift solenoid valve SLT to minutely control the clutch pressure in accordance with engine output and driving conditions. As a result, smooth shift characteristics are achieved.

        A01DLCXE01

    3. Lock-up Timing Control


      1. The ECM operates the lock-up timing control in order to improve the fuel consumption performance in the top gear when the shift lever is in D or 3.

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

        Tech Tips

        ○: Operates

        X: Does not operate

    4. Flex Lock-up Clutch Control


      1. In the low-to-mid-speed range, this flex lock-up clutch control regulates the shift solenoid valve SLU to provide an intermediate mode between the on and off operations of the lock-up clutch in order to improve the energy transmitting efficiency in this range. As a result, the operating range of the lock-up clutch has been increased and fuel economy has been improved. The flex lock-up clutch control operates in 3rd and 4th gears when the shift lever is in D, and in 3rd gear when the shift lever is in 3.

      2. Even when the vehicle is decelerating (the accelerator pedal is released), the flex lock-up clutch control operates. Therefore, the fuel-cut area of the engine has been expanded and fuel economy has been improved.

        A01DKWYE01
        A01DL70E04
        Flex Lock-up Clutch Control Operation
        Gear Shift Lever Position
        D 3
        1st X X
        2nd X X
        3rd ○* ○*
        4th ○* -

        Tech Tips

        ○: Operates

        X: Does not operate

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

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


      1. The AI-shift control determines optimal transmission control based on input signals and automatically changes the shift pattern. As a result, a high caliber of transmission operation is achieved.

      2. The AI-shift control includes a road condition support control and a driver's intention support control.

      3. The AI-shift control is effected only with the shift lever in D, based on the accelerator pedal and brake operation data. The AI-shift control will be canceled when the shift lever is moved to a position other than D.

        A01DKS5E01

      4. Under road condition support control, the ECM identifies the throttle valve opening angle, the accelerator pedal opening angle and the vehicle speed to determine whether the vehicle is being driven uphill or downhill. To achieve an optimal drive force while driving uphill, this control prevents the transmission from upshifting to 4th gear. To achieve an optimal engine braking effect while driving downhill, this control automatically downshifts the transmission to 3rd gear.

        A01DKZWE01

      5. The driver's intention support control is estimated based on the accelerator pedal operation and vehicle condition, and a shift pattern that is well-suited to the driver is selected.

  3. FUNCTION


    1. Shift Lock System


      1. The shift lock system prevents the shift lever from being moved to any position other than P, unless the ignition switch is ON and the brake pedal is depressed. This prevents the vehicle from starting off suddenly.

      2. The shift lock system is controlled by the shift lock control ECU sub-assembly and it has a shift lock function and key interlock function.

      3. The shift lock control ECU sub-assembly has a built-in P detection switch to detect the shift lever position, and receives input signals from the stop light switch assembly and ignition switch. Upon receiving these signals, the shift lock control ECU sub-assembly turns on the shift lock solenoid and the key interlock solenoid in order to release the shift lock and key interlock.

      4. The key interlock function prevents the key from being pulled out after the ignition switch has been turned off, unless the shift lever has been moved to P. Thus, the driver is urged to park the vehicle with the shift lever in P.

      5. A shift lock release button, which manually overrides the shift lock mechanism, is used.

        A01DL5XE01

    2. Shift Pattern Select System


      1. The shift pattern select system enables the driver to use a 2nd start switch (pattern select switch assembly) to select the 2nd start mode which allows the vehicle to start off in the 2nd gear, thus making it easy for the vehicle to start off on snowy, sandy or muddy terrain.

      2. When the 2nd start mode is selected while the shift lever is in D, 3 or 2, the vehicle can start off in the 2nd gear. After a start, if the shift lever is in D or 3, transmission will shift up automatically into 3rd or overdrive gears in the normal manner. If the shift lever is in 2, the transmission will continue to operate in the 2nd gear.

  4. CONSTRUCTION


    1. Torque Converter Clutch Assembly


      1. A compact, lightweight and high-capacity torque converter clutch assembly is used. The torque converter clutch supports lock-up clutch control, thus improving fuel economy.

        A01DKVHE01
        Text in Illustration
        *1 Lock-up Clutch *2 Pump Impeller
        *3 Turbine Runner *4 Stator
        *5 1-way Clutch - -

    2. Oil Pump Assembly


      1. The oil pump is operated by the torque converter clutch assembly. It lubricates the planetary gear units and supplies operating fluid pressure for hydraulic control. The front oil pump drive gear is continually driven by the engine via the pump impeller. The pump has sufficient capacity to supply the necessary fluid pressure throughout all speed ranges, as well as in reverse.

        A01DL9RE01
        Text in Illustration
        *1 Front Oil Pump Body Sub-assembly *2 O-ring
        *3 Front Oil Pump Drive Gear *4 Front Oil Pump Driven Gear
        *5 Stator Shaft Assembly *6 Oil Pump Cover

    3. Planetary Gear Unit


      1. The gear train consists of three multi-plate clutches, three multi-plate brakes, a single band type brake, three 1-way clutches, and three sets of planetary gears each consisting of a sun gear, a pinion gear and a ring gear.

        A01DL7TE01
        Text in Illustration
        *1 Overdrive Input Shaft *2

        Overdrive 1-way Clutch (F0)
        *3

        Overdrive Direct Clutch (C0)

        		 *4

        Overdrive Brake (B0)
        *5 Overdrive Planetary Gear Assembly *6 Input Shaft
        *7

        Direct Clutch (C2)

        		 *8

        2nd Coast Brake (B1)
        *9

        Forward Clutch (C1)

        		 *10 Front Planetary Gear Assembly
        *11

        1-way Clutch Assembly (F1)

        		 *12

        2nd Brake (B2)
        *13

        No. 2 1-way Clutch (F2)

        		 *14

        1st and Reverse Brake (B3)
        *15 Rear Planetary Gear Assembly *16 Output Shaft
        A01DL7KE01
        Text in Illustration
        *1 Overdrive Input Shaft *2 Overdrive Planetary Gear Assembly
        *3 Input Shaft *4 Front Planetary Gear Assembly
        *5 Rear Planetary Gear Assembly *6 Output Shaft

    4. Transmission Valve Body Assembly


      1. The transmission valve body assembly consists of the upper and lower valve bodies and 4 shift solenoid valves.

        A01DLCKE01
        Text in Illustration
        *1 Upper Valve Body *2 Plate
        *3 Lower Valve Body *4 Transmission Solenoid Assembly (S1)
        *5 Transmission Solenoid Assembly (S2) *6 Line Pressure Control Solenoid Assembly (SLT)
        *7 Shift Control Solenoid Assembly (SLU) - -
        A01DLBOE01
        Text in Illustration
        *1 Upper Valve Body *2 Secondary Regulator Valve
        *3 2-3 Shift Valve *4 Reverse Control Valve
        *5

        C2Check Valve

        		 *6

        B3Check Valve
        *7 Lock-up Relay Valve *8 3-4 Shift Valve
        *9 2nd Coast Modulator Valve - -
        A01DKRHE01
        Text in Illustration
        *1 Lower Valve Body *2 Lock-up Control Valve
        *3 Cut Back Valve *4 Solenoid Modulator Valve
        *5 Accumulator Control Valve *6 Primary Regulator Valve
        *7 1-2 Shift Valve *8 Low Coast Modulator Valve

    5. Shift Solenoid Valves S1 and S2


      1. The transmission solenoid assembly (S1 and S2) are 2-way solenoid valves.

      2. A filter is provided at the tip of the solenoid valve to further improve operational reliability.

        A01DKRRE01
        Text in Illustration
        *1 Transmission Solenoid Assembly (S1 and S2) *2 Filter
        *a Line Pressure *b Control Pressure
        Function of Shift Solenoid Valves S1 and S2
        Shift Solenoid Valve Function
        S1 Switches the 2-3 shift valve.
        S2 Switches the 1-2 shift valve and the 3-4 shift valve.

    6. Shift Solenoid Valves SLT and SLU


      1. In order to provide a hydraulic pressure that is proportional to the current that flows to the solenoid coil, the line pressure control solenoid assembly (SLT) linearly controls the line pressure based on the signals it receives from the ECM.

        A01DL9EE01

      2. In order to provide a hydraulic pressure that is proportional to the current that flows to the solenoid coil, the shift control solenoid assembly (SLU) linearly controls the lock-up clutch engagement pressure based on the signals it receives from the ECM.

        A01DLAZE01
        Function of Shift Solenoid Valves SLT and SLU
        Shift Solenoid Valve Function
        SLT

        • Line pressure control

        • Accumulator back pressure control
        SLU

        • Lock-up clutch pressure control

        • Accumulator back pressure control

    7. ATF Temperature Sensor


      1. No. 1 ATF temperature sensor, which is provided on the oil outlet, detects the ATF oil temperature necessary for shifting and for various controls and sends the information to the ECM.

      2. In addition, No. 2 ATF temperature sensor, which is provided on the transmission wire in the control valve portion, enables finer ECT control.

        A01DLC6E01
        Text in Illustration
        *1 No. 1 ATF Temperature Sensor *2 No. 2 ATF Temperature Sensor

    8. Speed Sensors


      1. This automatic transmission uses an input speed sensor (for NC0 signal) and an output speed sensor (for SP2 signal). Thus, the ECM can detect the timing of the shifting of the gears and appropriately control the engine torque and hydraulic pressure in response to various conditions.

      2. These speed sensors are the pick-up coil type.

      3. The input speed sensor detects the input speed of the transmission. The overdrive direct clutch drum is used as the timing rotor for this sensor.

      4. The output speed sensor detects the speed of the output shaft.

        A01DL7YE01
        Text in Illustration
        *1 Overdrive Direct Clutch Drum *2 Output Shaft
        *3 Input Speed Sensor *4 Output Speed Sensor

    9. Park/Neutral Position Switch Assembly and Transmission Control Switch


      1. The ECM uses the park/neutral position switch assembly and the transmission control switch to detect the shift lever position.

      2. The park/neutral position switch assembly sends the P, R, N, D, 2, L and NSW signals to the ECM. The ECM also sends signals for the shift position indicator "P, R, N, D, 2 and L" in the combination meter assembly via CAN.

      3. The transmission control switch is located in the shift lock control ECU sub-assembly. This switch sends the 3 signal to the ECM. The ECM also sends a signal for the shift position indicator "3" in the combination meter assembly via CAN.

        A01DL7RE01

    10. Shift Control Mechanism


      1. A gate type shift lever that uses a transmission control cable is used.

      2. The shift control mechanism consists of a transmission floor shift assembly and a transmission control cable assembly.

        A01DKV8E01
        Text in Illustration
        *1 Transmission Floor Shift Assembly *2 Shift Lever Knob
        *3 Transmission Control Cable Assembly - -
        *a Shift Pattern - -

  5. OPERATION


    1. Transaxle Power Flow

      Operating Condition
      Shift Lever Position and Gear Range Gear Position Shift Solenoid Valve Clutch Brake 1-way Clutch
      S1 S2

      C0

      C1

      C2

      B0

      B1

      B2

      B3

      F0

      F1

      F2

      P Park On Off ○ - - - - - - - - -
      R Reverse On Off ○ - ○ - - - ○ ○ - -
      N Neutral On Off ○ - - - - - - - - -
      D 1st On Off ○ ○ - - - - - ○ - ○
      2nd On On ○ ○ - - - ○ - ○ ○ -
      3rd Off On ○ ○ ○ - - ○ - ○ - -
      4th Off Off - ○ ○ ○ - ○ - - - -
      3 1st On Off ○ ○ - - - - - ○ - ○
      2nd On On ○ ○ - - - ○ - ○ ○ -
      3rd Off On ○ ○ ○ - - ○ - ○ - -
      2 1st On Off ○ ○ - - - - - ○ - ○
      2nd On On ○ ○ - - ○ ○ - ○ ○ -
      L 1st On Off ○ ○ - - - - - ○ - ○

      Tech Tips

      ○: Operates

      -: Does not operate


      1. 1st Gear (Shift Lever in D, 3 or 2)

        A01DLGC
        Text in Illustration
        A01DKX0 Operates - -

      2. 2nd Gear (Shift Lever in D or 3)

        A01DKQ2
        Text in Illustration
        A01DKX0 Operates - -

      3. 3rd Gear (Shift Lever in D or 3)

        A01DLIJ
        Text in Illustration
        A01DKX0 Operates - -

      4. 4th Gear (Shift Lever in D)

        A01DLAH
        Text in Illustration
        A01DKX0 Operates - -

      5. Engine Braking in 1st Gear (Shift Lever in L)

        A01DL4L
        Text in Illustration
        A01DKX0 Operates - -

      6. Engine Braking in 2nd Gear (Shift Lever in 2 or L)

        A01DKX1
        Text in Illustration
        A01DKX0 Operates - -

      7. Reverse Gear (Shift Lever in R)

        A01DKPQ
        Text in Illustration
        A01DKX0 Operates - -

  6. FAIL-SAFE


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

      Fail-safe Control List
      Malfunction Part Function
      Output Speed Sensor (SP2) During an output speed sensor malfunction, shift control is effected through the input speed sensor signal (NC0) or engine speed signal (NE).
      ATF Temperature Sensor During a malfunction of ATF temperature sensor, the system effects control by fixing the ATF temperature at 80°C (176°F).
      Transmission Solenoid Assembly (S1/S2) The current to the failed shift solenoid valve is cut off and control is effected by operating the other solenoid valves with normal operation.
      Line Pressure Control Solenoid Assembly (SLT) During a line pressure control solenoid assembly (SLT) malfunction, the current to the shift solenoid valve is stopped. This stops line pressure control, thus increasing shift-shock. However, shifting is effected through normal clutch pressure control.
      Shift Control Solenoid Assembly (SLU) During a shift control solenoid assembly (SLU) malfunction, the current to the shift solenoid valve is stopped. This stops lock-up control, thus decreasing fuel economy.

  7. DIAGNOSIS


    1. When the ECM detects a malfunction, it makes a diagnosis and memorizes the failed section. Furthermore, the ECM illuminates or blinks the MIL in the combination meter assembly to inform the driver.

    2. The ECM will also store the Diagnostic Trouble Codes (DTCs) of the malfunctions.

    3. The DTCs can be read by connecting an Global TechStream (GTS) to the DLC3.

    4. For details, refer to the Repair Manual.