CRUISE CONTROL SYSTEM DETAILS


  1. FUNCTION OF MAIN COMPONENTS


    1. The main components in the cruise control system have the following functions:

      Component Function
      Cruise Control Switch ON-OFF Button Turns the cruise control system on and off.
      CANCEL Switch A cancel signal is output to the power management control ECU when this switch is operated.
      +RES Switch The accelerate function and resuming of a preset speed can be performed by operating this switch. A signal is output to the power management control ECU when this switch is operated.
      -SET Switch The decelerate function and vehicle speed setting signals are output to the power management control ECU when this switch is operated.
      Power Management Control ECU

      • Controls all functions of the cruise control system in accordance with the signals from switches, sensors and ECUs.

      • If the power management control ECU detects a malfunction in the cruise control system, it will store Diagnostic Trouble Codes (DTCs).
      Inverter with Converter Assembly MG ECU Built into the inverter with converter assembly. Controls the motive force of MG2 in accordance with signals from the power management control ECU.
      ECM Actuates the throttle control motor in accordance with the signals from the power management control ECU.
      Brake Booster with Master Cylinder Assembly Skid Control ECU Transmits the VSC operation signal to the power management control ECU.
      Combination Meter Assembly Multi-information Display Cruise Control Indicator Light

      • Based on a cruise control indicator operation signal sent by the power management control ECU, the combination meter assembly illuminates the cruise control indicator when the cruise control system has been turned on using the ON-OFF button on the cruise control switch.

      • Based on a cruise control indicator operation signal sent by the power management control ECU, the combination meter assembly turns off the cruise control indicator if a malfunction occurs in the cruise control system.
      Cruise Control SET Indicator Light Illuminates while the cruise control system is controlling vehicle speed.
      Multi-information Display Displays a warning message to alert the driver in accordance with the signal provided by the power management control ECU.
      Hybrid Vehicle Transaxle Assembly MG2 Generates motive force for the wheels.
      Throttle Body with Motor Assembly Throttle Control Motor Adjusts the throttle valve opening angle in accordance with signals from the ECM.
      Throttle Position Sensor Detects the throttle valve opening angle and outputs it to the ECM.
      Accelerator Pedal Sensor Assembly Detects the accelerator pedal depression angle and transmits it to the power management control ECU.
      Shift Lever Position Sensor Detects the shift lever position and transmits signals to the power management control ECU.
      Stop Light Switch Assembly Detects when the brake pedal is depressed and transmits a signal to the power management control ECU.
      VSC OFF Switch Detects the VSC OFF signal and outputs it to the skid control ECU.
      Speed Sensor Detects the wheel speed of each of the 4 wheels.

  2. FUNCTION


    1. The cruise control system has the following control functions:

      Function Outline
      Constant Speed Control The power management control ECU compares the actual vehicle speed with the set speed. If the vehicle speed is higher than the set speed, the power management control ECU calculates optimal motive forces for the engine and MG2, and decelerates by adjusting the respective motive forces. If the vehicle speed is lower than the set speed, the power management control ECU calculates optimal motive forces for the engine and MG2, and accelerates by adjusting the respective motive forces.
      Set Control

      • When this system fulfils the following conditions, and the cruise control switch is moved to the -SET side and released, the power management control ECU stores the vehicle speed and maintains the vehicle constantly at that speed.


        • The cruise control system has been turned on using the ON-OFF button on the cruise control switch.

        • The vehicle is driving at a speed within the range of approximately 40 km/h (25 mph) or more.
      Low Speed Limit Control The low speed limit is the lowest speed that cruise control can be set at and it is designed to be approximately 40 km/h (25 mph). The cruise control system cannot be set below that speed. If the vehicle speed drops below that speed while the cruise control system is operating, speed control by the cruise control system will be canceled automatically. However, the set speed is kept in memory.
      COAST Switch Control

      • When the cruise control switch is held to the -SET side, the vehicle speed and the set vehicle speed change as follows:


        • The vehicle will decelerate.

        • The set vehicle speed will change to the speed at which the vehicle is being driven when the COAST switch (-SET side operation) is released.
      Tap Down Control

      • When the cruise control switch is moved momentarily (approximately 0.6 seconds or less) to the -SET side, the vehicle speed and the set vehicle speed change as follows:


        • The vehicle will decelerate in increments of approximately 1.0 km/h (1 mph) each time the switch is moved.

        • However, if the difference between the actual vehicle speed and the set vehicle speed is greater than 5 km/h (3 mph), the set vehicle speed will change to the speed at which the vehicle is being driven when the switch is pushed.
      ACC Switch Control

      • When the cruise control switch is held to the +RES side, the vehicle speed and the set vehicle speed change as follows:


        • The vehicle will accelerate.

        • The set vehicle speed will change to the speed at which the vehicle is being driven when the switch is released.
      Tap Up Control

      • When the cruise control switch is moved momentarily (approximately 0.6 seconds or less) to the +RES side, the vehicle speed and the set vehicle speed change as follows:


        • The vehicle will accelerate in increments of approximately 1.0 km/h (1 mph) each time the switch is moved.

        • However, if the difference between the actual vehicle speed and the set vehicle speed is greater than 5 km/h (3 mph), the set vehicle speed will not change.
      RES Switch Control If the vehicle speed is above the low speed limit, the cruise control resumes operation (when the cruise control switch is subsequently pushed to the +RES side to reach the vehicle speed that was set at the time the driver canceled cruise control. Even if the vehicle speed dropped below the low speed limit, the set speed can be resumed after the vehicle speed increases above the low speed limit.
      Manual Cancel Control

      • If any of the following signals are sent to the power management control ECU, cruise control speed control operation is canceled accordingly.


        • Stop light switch on signal (The brake pedal is depressed.)

        • Signals indicating that the shift lever has been moved from D to other position. (The shift lever is moved from D to N or B.)

        • CANCEL switch on signal (The cruise control switch is moved to the CANCEL side.)

        • Cruise control switch (ON-OFF button) off signal
      Automatic Cancel Control

      • If the following condition occurs while the cruise control system is controlling vehicle speed, the speed that is stored in memory is cleared and speed control by the cruise control system is canceled.


        • Stop light switch open or short circuit

      Furthermore, the master warning light illuminates, cruise control indicator light turns off, and a message indicating a malfunction will be displayed on the multi-information display until the cruise control system is turned off using the cruise control switch. The operation of the cruise control is disabled until the cruise control system is turned on again using the ON-OFF button.

      • If the following condition occurs while the cruise control system is controlling vehicle speed, the speed that is set in memory is cleared and speed control by the cruise control system is canceled.


        • Malfunction in the hybrid system

      Furthermore, speed control by the cruise control system is disabled until the cruise control system is turned on again using the ON-OFF button.

      • If any of the following conditions occur while the cruise control system is controlling vehicle speed, the speed that is set in memory is cleared and speed control by the cruise control system is canceled.


        • Stop light switch input signal is abnormal

        • Cancel circuit malfunction

        • Communication malfunction between the skid control ECU and power management control ECU

        • Brake control system malfunction

      Furthermore, the master warning light illuminates, cruise control indicator light turns off, and a message indicating a malfunction will be displayed on the multi-information display until the cruise control system is turned off using the cruise control switch. The operation of the cruise control is disabled until the power switch is turned off.

      • If the following condition occurs while the cruise control system is controlling vehicle speed, the speed that is set in memory is cleared and speed control by the cruise control system is canceled.


        • Vehicle speed decreases by 16 km/h (10 mph) or more below the speed at which the cruise control is set.

      • If the following condition occurs while the cruise control system is controlling vehicle speed, speed control by the cruise control system is canceled.


        • Vehicle speed decreases below the low speed limit (approximately 40 km/h [25 mph]).
      Shift-down Control When the vehicle is traveling uphill using cruise control, automatic transmission control may cause the transmission to shift down. During shift-down control, when the end of uphill travel is determined based on the throttle valve angle, the transmission will shift up after a certain period of time. When the transmission shifts down during ACC switch control or RES switch control, the transmission will shift up after ACC switch control or RES switch control ends.
      Other Cancelation Conditions

      • TR(A)C operates for a certain period of time during cruise control driving.

      • VSC operation.

  3. CONSTRUCTION


    1. Cruise Control Switch


      1. The cruise control switch consists of the ON-OFF button and the +RES, -SET and CANCEL switches. The +RES, -SET and CANCEL switches are operated by moving the lever in the 3 directions indicated.

      2. The switches in the cruise control switch are of the automatic reset (normally open) type that turn on only when the switch is being operated and turn off as soon as the driver releases the switch. Furthermore, the functions of the switch are active only when the cruise control system has been turned on using the ON-OFF button on the cruise control switch.

        A01HX59E02
        Text in Illustration
        *1 Cruise Control Switch - -
        *a ON-OFF Button *b +RES Switch
        *c -SET Switch *d CANCEL Switch

  4. OPERATION


    1. Combination Meter Assembly


      1. The combination meter assembly provides a cruise control indicator light, cruise control SET indicator light and multi-information display to indicate the condition of the cruise control system.

        Condition Cruise Control Indicator Light/ Cruise Control Set Indicator Light/ Multi-information Display*1
        Set Standby A01HWZR
        Being Controlled*2 A01HX8R A01HX9K
        System Malfunction A01HX4B

        Tech Tips

        *1: These illustrations are examples.

        *2: While driving at a set speed of 60 mph (97 km/h).

  5. DIAGNOSIS


    1. If a malfunction occurs in the cruise control system during cruise control operation, the power management control ECU cancels cruise control operation, illuminates the master warning light and turns off the cruise control indicator light and cruise control SET indicator light. At this time, "Check Cruise Control System" is displayed on the multi-information display. The power management control ECU stores the malfunction in the form of a 5-digit Diagnostic Trouble Code (DTC).

    2. The 5-digit DTC can be read by connecting the Techstream to the DLC3. For details, refer to the Repair Manual.