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Home >> Lexus >> 2017 >> NX 300h >> Repair and Diagnosis >> Accessories & Equipment >> Cruise Control Systems >> Cruise Control System - Diagnostics - Introduction >> Cruise Control System >> System Description [10/2014 - 09/2017] >> System Description [10/2014 - 09/2017]
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System Description [10/2014 - 09/2017]

  1. CRUISE CONTROL SYSTEM 

    This system is controlled by the hybrid vehicle control ECU, and control is performed using the throttle with motor body assembly and motor drive force. The hybrid vehicle control ECU controls the following functions: ON-OFF, -SET, +RES, CANCEL, vehicle speed operation and shift down control.

    • The hybrid vehicle control ECU compares the vehicle speed from the speed sensor with the stored vehicle speed set using the cruise control main switch. The hybrid vehicle control ECU instructs the throttle valve motor of the throttle with motor body assembly to close the valve and the motor generator to decrease the motor drive force when the vehicle speed is greater than the stored speed, and instructs the throttle valve motor to open the valve and the motor generator to increase the motor drive force when the vehicle speed is less than the stored speed.
    • The hybrid vehicle control ECU receives signals such as ON/OFF, -SET, +RES, and CANCEL from the cruise control main switch and executes the command.
    • The hybrid vehicle control ECU illuminates the combination meter assembly cruise control indicator light when it receives the cruise control main switch on signal.
    • The hybrid vehicle control ECU turns off the combination meter assembly cruise control indicator light and displays a warning message when a malfunction occurs during cruise control driving.
    • The hybrid vehicle control ECU illuminates the combination meter assembly cruise control SET indicator light when vehicle speed control begins after the cruise control main switch is pushed to -SET while driving.
      Fig 1: Identifying Cruise Control SET Indicator
      GTY370223Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Cruise Control Indicator Light
      *2 Cruise Control SET Indicator Light
    • The hybrid vehicle control ECU cancels control of vehicle speed when the brake pedal is depressed and the hybrid vehicle control ECU receives a signal from the stop light switch assembly.
    • The hybrid vehicle control ECU cancels control of vehicle speed when the shift lever is moved from D to any other position.
    • The hybrid vehicle control ECU cancels control of vehicle speed when the cruise control main switch is pulled to CANCEL.
    • The hybrid vehicle control ECU cancels control of vehicle speed when the cruise control system is turned off using the cruise control main switch.
  2. LIMIT CONTROL 
    1. Low speed limit

      The lowest possible set speed is approximately 40 km/h (25 mph). The cruise control system cannot be set when the vehicle speed is below the low speed limit. Control of vehicle speed will be automatically canceled but the stored vehicle speed will be retained when the vehicle speed drops below the low speed limit while the cruise control is controlling vehicle speed.

    2. High speed limit

      The highest possible set speed is approximately 200 km/h (124 mph). The cruise control system cannot be set when the vehicle speed is over the high speed limit. Also, +RES cannot be used to increase the speed beyond the high speed limit.

  3. OPERATION OF CRUISE CONTROL 

    The cruise control main switch is used to turn the cruise control system on and off, as well as operate 7 functions: SET, - (COAST), TAP-DOWN, RES (RESUME), + (ACCEL), TAP-UP, and CANCEL. The SET, TAP-DOWN, and - (COAST) functions, and the RES (RESUME), TAP-UP, and + (ACCEL) functions are operated with the same switch. The cruise control main switch is an automatic return type switch which turns on only while being operated in the direction of each arrow, and turns off when it is released.

    1. SET CONTROL

      The vehicle speed is stored and speed control begins when the cruise control main switch is pushed to -SET while driving with the cruise control system on (while the cruise control indicator light is illuminated), and the vehicle speed is within the set speed range (between the low and high speed limits).

    2. - (COAST) CONTROL

      When the cruise control system is controlling vehicle speed and the cruise control main switch is pushed to -SET and held in that position, the cruise control system sends "throttle valve opening angle 0°" and "motor drive force decreasing" demand signals to the hybrid vehicle control ECU. Following this, the vehicle speed is stored and maintained when the cruise control main switch is released.

      HINT: 

      An actual throttle valve opening angle of 0° is not possible due to items such as idle speed control.

    3. TAP-DOWN CONTROL

      When the cruise control system is controlling vehicle speed and the cruise control main switch is tapped to the -SET side (for approximately 0.6 seconds or less), the stored vehicle speed decreases by approximately 1.6 km/h (1 mph) for each time the switch is tapped. When the cruise control main switch is tapped to -SET and the difference between the current and stored vehicle speed is more than approximately 5 km/h (3 mph), the current vehicle speed is stored and speed control is performed.

    4. ACCELERATION CONTROL

      When the cruise control system is controlling vehicle speed and the cruise control main switch is pushed to +RES and held in that position, the cruise control system sends a signal to the hybrid vehicle control ECU to operate the throttle valve motor of the throttle with motor body assembly to open the throttle valve and the motor generator to increase the motor drive force. Following this, the vehicle speed is stored and maintained when the cruise control main switch is released.

    5. TAP-UP CONTROL

      When the cruise control system is controlling vehicle speed and the cruise control main switch is tapped to the +RES side (for approximately 0.6 seconds or less), the stored vehicle speed increases by approximately 1.6 km/h (1 mph) for each time the switch is tapped. When the cruise control main switch is tapped to +RES and the difference between the current and stored vehicle speed is more than approximately 5 km/h (3 mph), the stored vehicle speed will not be changed.

    6. RESUME CONTROL

      If control of vehicle speed by the cruise control system was canceled due to any of the manual cancel conditions (other than turning the cruise control system off using the cruise control main switch), and if the vehicle speed is between the low and high speed limits, the stored vehicle speed from the time of cancelation will be resumed and maintained when the cruise control main switch is pushed to +RES.

    7. MANUAL CANCEL CONTROL

      Performing any of the following cancels control of vehicle speed by the cruise control system (the stored vehicle speed in the hybrid vehicle control ECU is maintained).

      • Depressing the brake pedal.
      • Moving the shift lever from D to any other position.
      • Pulling the cruise control main switch to CANCEL.
      • Turning the cruise control system off using the cruise control switch (the stored vehicle speed in the ECM is not maintained).
    8. Auto cancel

      Performing any of the following cancels the cruise control system (the stored vehicle speed in the hybrid vehicle control ECU is not maintained).

      • Actual vehicle speed is more than approximately 10 mph (16 km/h) below the set vehicle speed.
      • Actual vehicle speed falls below approximately 25 mph (40 km/h).
      • VSC is activated.
      • TRAC is activated for a period of time.
      • When the VSC or TRAC system is turned off by pressing the VSC OFF switch.
      • Pre-collision braking is activated.
  4. AUTO CANCEL (FAIL-SAFE) 

    This system has an automatic cancellation function (fail-safe).

    Refer to FAIL-SAFE CHART [10/2014 - 09/2017] 

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