DYNAMIC RADAR CRUISE CONTROL SYSTEM


  1. FUNCTION OF MAIN COMPONENTS


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

      Component Function
      Cruise Control Switch ON-OFF Button Turns the cruise control system on and off.
      MODE Switch Switches between constant speed control mode and vehicle-to-vehicle distance control mode.
      CANCEL Switch A cancel signal is output to the driving support ECU assembly when this switch is operated.
      +RES Switch Acceleration and resuming of a preset speed can be performed by operating this switch. A signal is output to the driving support ECU assembly when this switch is operated.
      -SET Switch Deceleration function is operated and vehicle speed setting signals are output to the driving support ECU assembly when this switch is operated.
      Steering Pad Switch Assembly Vehicle-to-vehicle Distance Control Switch While the system is in vehicle-to-vehicle distance control mode, the driver can operate the vehicle-to-vehicle distance control switch to select the vehicle-to-vehicle distance in 3 levels: long, middle and short.
      Hybrid Vehicle Control ECU Assembly

      • Increases and decreases the motive force in accordance with the motive force request signals transmitted by the driving support ECU assembly.

      • Transmits information about motive forces that are actually generated and that can be sent to the driving support ECU assembly.
      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 hybrid vehicle control ECU assembly.
      Stop Light Switch Assembly Detects the brake pedal being depressed and transmits its signal to the hybrid vehicle control ECU assembly.
      Millimeter Wave Radar Sensor Assembly Radiates millimeter radar waves forward, uses the reflected waves to detect the presence of a vehicle traveling ahead, the vehicle-to-vehicle distance, and the relative speed, and then transmits this information to the driving support ECU assembly.
      Driving Support ECU Assembly

      • Calculates the motive force required to achieve the target vehicle speed/target vehicle-to-vehicle distance based on signals from switches, sensors and ECUs and transmits motive force request signals to the hybrid vehicle control ECU assembly assembly (to accelerate the vehicle in accordance with the motive force request) and the skid control ECU assembly (to decelerate the vehicle in accordance with the motive force request).

      • Determines presence of a preceding vehicle based on information from the millimeter wave radar sensor assembly.

      • Transmits control status display request signals, warning display request signals and diagnosis signals for the dynamic radar cruise control system.
      Combination Meter Assembly Cruise Control Indicator (Constant Speed Control Mode)*1

      • Based on a cruise control indicator operation signal sent by the driving support ECU assembly, the combination meter assembly illuminates the cruise control indicator light when the cruise control system has been turned on using the ON-OFF button on the cruise control switch and constant speed control mode has been selected.

      • Based on a cruise control indicator operation signal sent by the driving support ECU assembly, the combination meter assembly turns off the cruise control indicator light if a malfunction occurs in the cruise control system.
      Radar Cruise Control Indicator (Vehicle-to-vehicle Distance Control Mode)*1

      • Based on a cruise control indicator operation signal sent by the driving support ECU assembly, the combination meter assembly illuminates the cruise control indicator light 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 driving support ECU assembly, the combination meter assembly turns off the cruise control indicator light if a malfunction occurs in the cruise control system.
      Cruise Control SET Indicator*1 Illuminates when the vehicle speed is set.
      Multi-information Display*1, *2 During dynamic radar cruise control operation, the multi-information display receives signals from the driving support ECU assembly in order to display the system conditions.
      Multi-information Display*2 Cruise Control Indicator (Constant Speed Control Mode)

      • Based on a cruise control indicator operation signal sent by the driving support ECU assembly, 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 and constant speed control mode has been selected.

      • Based on a cruise control indicator operation signal sent by the driving support ECU assembly, the combination meter assembly turns off the cruise control indicator if a malfunction occurs in the cruise control system.
      Radar Cruise Control Indicator (Vehicle-to-vehicle Distance Control Mode)

      • Based on a cruise control indicator operation signal sent by the driving support ECU assembly, 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 driving support ECU assembly, the combination meter assembly turns off the cruise control indicator if a malfunction occurs in the cruise control system.
      Cruise Control SET Indicator Illuminates when the vehicle speed is set.
      Multi Buzzer If the driving support ECU assembly detects automatic cancel or warning signals while the vehicle is operating under cruise control, this buzzer sounds to inform the driver.
      Steering Sensor Detects the angle and direction of steering and transmits signals to the driving support ECU assembly.
      Yawrate Sensor Detects the yaw rate of the vehicle and transmits signals to the driving support ECU assembly.
      Transmission Floor Shift Assembly Transmission Control Switch

      • Detects the shift lever position and transmits signals to the hybrid vehicle control ECU assembly.

      • Informs the hybrid vehicle control ECU assembly of driver upshift or downshift operations while the shift lever is in S.
      Shift paddle Switch (Transmission Shift Switch Assembly) While the vehicle is being driven in D mode or S mode, this switch outputs a signal to the hybrid vehicle control ECU assembly when the switch is pulled to "+" or "-".
      Skid Control ECU Assembly

      • While the system is operating in vehicle-to-vehicle distance control mode, the skid control ECU assembly performs brake control in accordance with request signals from the driving support ECU assembly.

      • Transmits signals such as wheel speed and estimated vehicle acceleration to the driving support ECU assembly.
      ECM Actuates the throttle control motor in accordance with the signals from the hybrid vehicle control ECU assembly.
      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.
      Hybrid Vehicle Transaxle Assembly MG2 Generates motive force for the wheels.
      Skid Control Buzzer Assembly Sounds a buzzer when it receives a signal from the millimeter wave radar sensor assembly to alert the driver that the distance between vehicles is short.
      Speed Sensor Detects the wheel speed of each of the 4 wheels.
      Accelerator Pedal Sensor Assembly Detects the accelerator pedal depression angle and transmits it to the hybrid vehicle control ECU assembly.
      Shift Lever Position Sensor Detects the shift lever position and transmits signals to the hybrid vehicle control ECU assembly.
      Combination Switch Assembly VSC (TRC) OFF Switch Detects the VSC (TRC) OFF signal and outputs it to the skid control ECU assembly.

      *1: F SPORT

      *2: Except F SPORT

  2. SYSTEM CONTROL


    1. The dynamic radar cruise control system is controlled by the driving support ECU assembly. The driving support ECU assembly increases and decreases the vehicle speed by controlling the engine, MG2 and brake through the motive force request signals.

    2. The combination meter assembly informs the driver of the control conditions.

    3. The cruise control switch (mode switch) is used for switching between constant speed control mode and vehicle-to-vehicle distance control mode. The mode in which the cruise control system starts is the vehicle-to-vehicle distance control mode.

    4. For vehicles with the dynamic radar cruise control system, constant speed control mode is controlled by the driving support ECU assembly, which outputs signals to the MG ECU.

    5. Vehicle-to-vehicle distance control mode is controlled by the millimeter wave radar sensor assembly and driving support ECU assembly. Thus, the signals are output to the actuators and the ECU while exchanging data as indicated below.

      A01WX47E02

  3. FUNCTION


    1. Function List


      1. The control of the dynamic radar cruise control system varies depending on the mode:

        A: Constant Speed Control Mode

        B: Vehicle-to-vehicle Distance Control Mode

        Function Outline Mode
        A B
        Constant Speed Control Controls the motive force through the hybrid vehicle control ECU assembly and skid control ECU Assembly, and adjusts the vehicle speed to the set vehicle speed. ○ ○
        Deceleration Control Performs engine, MG2 and brake control in order to decelerate the vehicle so that the vehicle-to-vehicle distance between the driver's own vehicle and the vehicle ahead is maintained at the set distance. - ○
        Follow-up Control After performing deceleration control, the driver's own vehicle follows the vehicle ahead in order to maintain the proper vehicle-to-vehicle distance. The actual distance maintained for each distance level (long, medium and short) varies in accordance with vehicle speed. - ○
        Acceleration Control Accelerates the vehicle in order to attain the set vehicle speed if the vehicle ahead or the driver's own vehicle has changed lanes. - ○
        Set Control When the cruise control system has been turned on using the ON-OFF button on the cruise control switch, either of the relevant vehicle speed conditions shown below is met, and the cruise control switch is moved to the -SET side and released, the driving support ECU assembly stores the vehicle speed and maintains the vehicle constantly at that speed. ○ ○
        The vehicle is traveling at a speed within the range of approximately 50 km/h (32 mph) or more. ○ ○
        Low Speed Limit Control The low speed limit is the lowest speed that cruise control can be operated at and it is designed to be approximately 40 km/h (25 mph). The cruise control cannot be operated below that speed. If the vehicle speed drops below that speed while the cruise control is set and working to maintain vehicle speed, the cruise control will be canceled automatically. The set vehicle 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 according to the mode: ○ ○

        • The vehicle decelerates constantly.

        • The set vehicle speed changes to the speed at which the switch is released.

        		 ○ -

        • The set vehicle speed decreases in increments of 5 km/h or 5 mph. (Example: 103 → 100 → 95 km/h [mph])

        • The vehicle will remain at the speed at which the vehicle is being driven when the -SET switch 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 according to the mode: ○ ○

        • The vehicle will decelerate in increments of approximately 1.6 km/h (1 mph) for 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.

        		 ○ -
        The vehicle will decelerate in increments of approximately 5 km/h (3 mph)*1 or 1 km/h (1 mph)*2 each time the switch is moved. - ○
        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 according to the mode: ○ ○

        • The vehicle will accelerate constantly.

        • The set vehicle speed changes to the speed at which the switch is released.

        		 ○ -

        • The set vehicle speed increases in increments of 5 km/h or 5 mph. (Example: 103 → 105 → 110 km/h [mph])

        • The vehicle will accelerate to the speed that is set at the time the switch is released. However, only the set vehicle speed will change during follow-up control.

        		 - ○
        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 moved to the +RES side) to reach the vehicle speed that was set at the time the driver canceled cruise control. ○ ○
        If the vehicle ahead changes driving lanes during follow-up control, the vehicle speed is gradually increased to the set vehicle speed. At this time, the vehicle speed can be increased promptly by moving the cruise control switch to the +RES side. - ○
        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 1.6 km/h (1 mph) for 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.

        		 ○ -
        The vehicle will accelerate in increments of approximately 5 km/h (3 mph)*1 or 1 km/h (1 mph)*2 for each time the switch is moved. - ○
        Manual Cancel Control

        If any of the following signals are sent to the hybrid vehicle control ECU assembly, speed control by the cruise control system is canceled accordingly.


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

        • Shift lever is moved from D or S to any other position.

        • When 1st, 2nd or 3rd range is selected in S mode.

        • When 1st, 2nd or 3rd range is selected in D or S position by shift paddle switch (transmission shift switch assembly)

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

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

        • TRC operates for a certain period of time during cruise control driving.

        • VSC operation.

        		 ○ ○
        Automatic Cancel Control When an automatic cancel signal is sent to the driving support ECU assembly, speed control by the cruise control system is canceled. At this time, the type of warning sent to the driver and the control resumption condition vary according to the cancel signal. ○ ○
        Mode Switching Control

        The following operations switch modes:


        1. Turn the cruise control system on using the ON-OFF button on the cruise control switch (the cruise control will start in vehicle-to-vehicle distance control mode).

        2. Hold the cruise control switch to the MODE side for approximately 1 second or more.


          • If the switch is moved to any other side before the modes are switched, turn the cruise control system off and then perform steps (1) and (2) again.

        		 ○ ○

        *1:Models for Europe

        *2:Except models for Europe

        Tech Tips

        ○: Available

        -: Not Available

    2. Constant Speed Control


      1. The driving support ECU assembly compares the actual vehicle speed (wheel speed signal from the skid control ECU assembly) with the set vehicle speed under constant speed control in each control mode. When the actual vehicle speed differs from the set vehicle speed, the driving support ECU assembly calculates the motive force required to achieve the set vehicle speed and transmits motive force request signals to the hybrid vehicle control ECU assembly, thus controlling the motive force optimally and adjusting the actual vehicle speed to the set vehicle speed.

      2. In vehicle-to-vehicle distance control mode, the driving support ECU assembly performs deceleration control, follow-up control or acceleration control based on the information about the vehicle ahead transmitted from the millimeter wave radar sensor assembly.

        A01WX5VE02

    3. Deceleration Control


      1. The driving support ECU assembly calculates the target deceleration rate in accordance with signals from the millimeter wave radar sensor assembly, and transmits a motive force request signal to the hybrid vehicle control ECU assembly and the skid control ECU assembly. Upon receiving this signal, these ECUs control the motive force and decelerate the vehicle.

        A01WX0OE02

      2. This control is not performed in the presence of a parked vehicle or object, or below the settable vehicle speed range.

      3. If the driving support ECU assembly determines that further deceleration is necessary, it transmits a brake request signal to the skid control ECU assembly. Upon receiving this signal, the skid control ECU assembly then activates the brake actuator to apply the brakes.

      4. At this time, if the deceleration rate is higher than a predetermined value, the skid control ECU assembly outputs a stop light illumination request signal to the stop light control relay in order to inform anyone who might be following the vehicle.

        A01WX6LE03

      5. If the vehicle is not decelerating adequately, the skid control ECU assembly sounds millimeter wave radar sensor assembly based on a request signal from the driving support ECU assembly. The buzzer is sounded to urge the driver to depress the brake pedal.

        A01WX67E03

    4. Follow-up Control


      1. After performing deceleration control, the driving support ECU assembly transmits motive force request signals to the hybrid vehicle control ECU assembly and the skid control ECU assembly so that the vehicle can follow the vehicle ahead while maintaining the proper vehicle-to-vehicle distance. The actual distance maintained for each distance level (long, middle and short) varies in accordance with vehicle speed. Upon receiving these signals, these ECUs control the motive force in order to perform follow-up control.

      2. 3 levels (long, middle, and short) of vehicle-to-vehicle distance can be selected by operating the vehicle-to-vehicle distance control switch.

        A01WX1SE04

    5. Acceleration Control


      1. If the driving support ECU assembly detects that either the vehicle ahead or own vehicle has changed lanes, a motive force request signal is transmitted to the hybrid vehicle control ECU assembly in order to attain the set vehicle speed. Upon receiving this signal, the hybrid vehicle control ECU assembly controls the motive force of the engine and MG2 in order to perform acceleration control.

        A01WX5EE02

    6. Automatic Cancel Control


      1. If any of the conditions listed below occur while the vehicle is being driven using cruise control, speed control by the cruise control system will be canceled. Then, the following warning items will appear for the driver.

        Constant Speed Control Mode
        Situation Warning
        Multi-information Display Master Warning Light Buzzer in the combination meter assembly

        If the condition listed below occurs, the driving support ECU assembly clears the set vehicle speed and cancels speed control by the cruise control system.


        • Stop light switch open or short circuit

        Speed control by the cruise control system is disabled until the conditions are corrected or the cruise control system is turned off and back on again using the ON-OFF button on the cruise control switch.

        		 Check Cruise Control System Illuminates Sounds once

        If the conditions listed below occur, the driving support ECU assembly clears the set vehicle speed and cancels speed control by the cruise control system.


        • Malfunction in the dynamic radar cruise control system other than those given above

        Speed control by the cruise control system is disabled until the power switch is turned off (IG) again.

        		 Check Cruise Control System Illuminates Sounds once

        If the condition listed below occurs, the driving support ECU assembly clears the set vehicle speed and cancels speed control by the cruise control system.


        • Malfunction in the hybrid system

        Speed control by the cruise control system is disabled until the condition is corrected or the cruise control system is turned off and back on again using the ON-OFF button on the cruise control switch.

        		 - Does not illuminate -

        If the following condition occurs, the driving support ECU assembly clears the set vehicle speed and cancels the cruise control.


        • The vehicle speed drops more than 16 km/h (10 mph) below the set vehicle speed

        		 - Does not illuminate -

        If the condition listed below occurs, the driving support ECU assembly cancels speed control by the cruise control system while retaining the set vehicle speed in its memory.


        • The vehicle speed drops below low speed limit (approximately 40 km/h [25 mph])

        		 - Does not illuminate -
        Vehicle-to-vehicle Distance Control Mode
        Situation Warning
        Multi-information Display Master Warning Light Buzzer in the combination meter assembly

        If the condition listed below occurs, the driving support ECU assembly clears the set vehicle speed and cancels speed control by the cruise control system.


        • Stop light switch open or short circuit

        Cruise control is prohibited until the condition is corrected or the cruise control system is turned off and back on again using the ON-OFF button on the cruise control switch.

        		 Check Cruise Control System Illuminates Sounds once

        If one of the conditions listed below occurs, the driving support ECU assembly clears the set vehicle speed and cancels speed control by the cruise control system.


        • Malfunction of the millimeter wave radar sensor assembly

        • Misalignment of the axis of the millimeter wave radar sensor assembly

        • Malfunction in the dynamic radar cruise control system other than those given above

        Speed control by the cruise control system is disabled until the power switch is turned off (IG) again.

        		 Check Cruise Control System Illuminates Sounds once

        If the condition listed below occurs, the driving support ECU assembly clears the set vehicle speed and cancels speed control by the cruise control system.


        • Malfunction in the hybrid system

        Speed control by the cruise control system is prohibited until the condition is corrected or the cruise control system is turned off and back on again using the ON-OFF button on the cruise control switch.

        		 - Does not illuminate -

        If the condition listed below occurs, the driving support ECU assembly cancels speed control by the cruise control system while retaining the set vehicle speed in its memory.


        • The millimeter wave radar sensor assembly is dirty

        Cruise control is prohibited until the condition is corrected or the cruise control system is turned off and back on again using the ON-OFF button on the cruise control switch.

        		 Clean Radar Sensor Illuminates Sounds once

        If either of the conditions listed below occurs, the driving support ECU assembly cancels speed control by the cruise control system while retaining the set vehicle speed in its memory.


        • The wipers operate at HI speed

        • The measurement becomes extremely unstable due to poor weather conditions

        Cruise control is prohibited until the condition is corrected or the cruise control system is turned off and back on again using the ON-OFF button on the cruise control switch.

        		 Cruise Control not available Illuminates Sounds once

        If the condition listed below occurs, the driving support ECU assembly cancels speed control by the cruise control system while retaining the set vehicle speed in its memory.


        • The vehicle speed drops below the low speed limit (approximately 40 km/h [25 mph])

        		 - Does not illuminate Sounds once

  4. DIAGNOSIS


    1. If a malfunction occurs in the dynamic radar cruise control system during cruise control operation, the driving support ECU assembly cancels cruise control operation, illuminates the master warning light and turns off the cruise control indicator (constant speed control mode) or radar cruise control indicator (vehicle-to-vehicle distance control mode), and cruise control SET indicator. Also, "Check Cruise Control System" is displayed on the multi-information display to inform the driver of a malfunction. At the same time, the malfunction is stored in memory as a 5-digit Diagnostic Trouble Code (DTC).

    2. The DTC can be read when the Global TechStream (GTS) is connected to the DLC3. For details, refer to the Repair Manual.