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 Main 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 Distance Control Switch While the system is in vehicle-to-vehicle distance control mode, the driver can operate the distance control switch to select the vehicle-to-vehicle distance in 3 levels: long, middle and short.
      EV Control ECU

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

      • Transmits the information about motive forces that are actually generated and can be generated to the driving support ECU assembly.
      Inverter with Converter Assembly MG ECU Built into the inverter with converter assembly. Controls the motive force of traction motor in accordance with signals from the EV control ECU.
      Stop Light Switch Assembly Detects the depression of the brake pedal and transmits a signal to the driving support 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.

      • Sounds the driving support buzzer (skid control buzzer) according to signals from 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 EV control ECU (to accelerate the vehicle in accordance with the motive force request) and the skid control ECU (to decelerate the vehicle in accordance with the motive force request).

      • Determines the 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 Light

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

      • Based on a cruise control indicator light 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 Light

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

      • Based on a radar cruise control indicator light operation signal sent by the driving support ECU assembly, the combination meter assembly turns off the radar cruise control indicator light if a malfunction occurs in the cruise control system.
      Cruise SET Indicator Light Illuminates when the vehicle speed is set.
      Master Warning Light Illuminates when a system malfunction occurs.
      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.
      Multi-information Display

      • By selecting the driving assist system tab, the system control status can be displayed.

      • 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.
      Steering Angle Sensor Detects the angle and direction of steering and transmits signals to the driving support ECU assembly.
      Airbag ECU Assembly Yaw Rate Sensor Detects the yaw rate of the vehicle and transmits signals to the driving support ECU assembly.
      Skid Control ECU

      • Performs brake control in accordance with motive force request signals from the driving support ECU assembly while the system is operating in vehicle-to-vehicle distance control mode.

      • Transmits signals such as a wheel speed and estimated vehicle acceleration to the driving support ECU assembly.

      • Illuminates the stop lights during brake control.
      FCV Transaxle with Motor Assembly Traction Motor Generates motive force for the wheels.
      Driving Support Buzzer (Skid Control Buzzer) 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.
      Accelerator Pedal Sensor Assembly Detects the accelerator pedal depression degree and outputs it to the EV control ECU.
      Speed Sensor Detects the wheel speed and transmits signals to the skid control ECU.
      Transmission Instrument Panel Shift Assembly Shift Lever Position Sensor Converts the shift position into an electrical signal and outputs it to the EV control ECU.
      Network Gateway ECU Relays and transmits each CAN communication data signal.
      Windshield Wiper Switch Assembly Transmits windshield wiper switch information (HI position) to the driving support ECU assembly.

  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 traction motor and brake through the motive force request signals.

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

    3. The cruise control main 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.

      A01MA6TE01

  3. FUNCTION


    1. Control of Dynamic Radar Cruise Control System Varies Depending on 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 driving support ECU assembly via the EV control ECU and the skid control ECU in order to adjust the vehicle speed to the set speed. ○ ○
      Deceleration Control Effects traction motor and brake control in order to decelerate the vehicle so that the vehicle-to-vehicle distance between this vehicle and the preceding vehicle equals the set distance. - ○
      Follow-up Control After effecting deceleration control, the vehicle follows the preceding vehicle in order to maintain the proper vehicle-to-vehicle distance in accordance with the vehicle speed. - ○
      Acceleration Control Accelerates the vehicle in order to attain the set vehicle speed if the preceding vehicle or this vehicle has changed lanes. - ○
      Set Control

      While this system fulfills the following conditions and the cruise control main switch is pressed to the -SET side and released, the driving support ECU assembly stores the vehicle speed, illuminates the cruise SET indicator light on the combination meter assembly and maintains the vehicle constantly at that speed.


      • The ON-OFF button on the cruise control main switch is pushed.

      		 ○ ○

      • The vehicle speed is approximately 50 km/h (30 mph) or more. However, if the vehicle speed is 200 km/h (125 mph) or greater, the set vehicle speed is set to 200 km/h (125 mph).

      		 ○ -

      • The vehicle speed is approximately 50 km/h (30 mph) or more. However, if the vehicle speed is 170 km/h (105 mph) or greater, the set vehicle speed is set to 170 km/h (105 mph).

      		 - ○
      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 driving using cruise control, the cruise control system will be canceled automatically. The set vehicle speed is kept in memory. ○ ○
      COAST (-) Switch Control While the cruise control main switch is held to the -SET side, the vehicle speed and the set vehicle speed change in accordance with the mode as follows: ○ ○

      • 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 remains at the speed that the vehicle is traveling at when the cruise control main switch is released.

      		 - ○
      Tap-down Control When the cruise control main switch is pushed momentarily (approximately 0.6 seconds) to the -SET side, the vehicle speed and the set vehicle speed change in accordance with the mode as follows: ○ ○

      • The vehicle decelerates in increments of approximately 1.6 km/h (1 mph) for each time the switch is pressed.

      • 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 changes to the speed at which the vehicle was being driven at the time the switch was operated.

      		 ○ -

      • The vehicle decelerates in increments of approximately 5 km/h or 5 mph for each time the switch is pressed. (Example: 103 → 100 → 95 km/h [mph])

      		 - ○
      ACC (+) Switch Control When the cruise control main switch is pushed to the +RES side and held, the vehicle speed and the set vehicle speed change in accordance with the mode as follows: ○ ○

      • The vehicle accelerates 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: 83 → 85 → 90 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.

      		 - ○
      Tap-up Control When the cruise control main switch is pushed momentarily (approximately 0.6 seconds) to the +RES side, the vehicle speed and the set vehicle speed change in accordance with the mode as follows: ○ ○

      • The vehicle accelerates in increments of approximately 1.6 km/h (1 mph) for each time the switch is pressed.

      • 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 does not change.

      		 ○ -

      • The vehicle accelerates in increments of approximately 5 km/h or 5 mph for each time the switch is pressed. (Example: 83 → 85 → 90 km/h [mph])

      		 - ○
      RES Switch Control If the vehicle speed is above the low speed limit, the cruise control resumes operation (subsequently pushes the cruise control main switch to the +RES side) to reach the vehicle speed that was set at the time the driver canceled cruise control. ○ ○
      If the preceding vehicle 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 pushing the cruise control main switch to the +RES side. - ○
      Manual Cancel Control

      If any of the following signals are sent to the driving support ECU assembly, the cruise control is canceled accordingly:


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

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

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

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

      		 ○ ○
      Automatic Cancel Control When an automatic cancel signal is sent to the driving support ECU assembly, the cruise control operation is canceled. At this time, the style of the warning to the driver and the control resumption condition varies in accordance with the cancel signal. ○ ○
      Mode Switching Control

      The following operations switch the modes:


      • ON-OFF button on the cruise control main switch is on. (Starts in the vehicle-to-vehicle distance control mode.)

      • Cruise control main switch is held in the MODE side. (Approximately 1 second or more)

      • If the switch is pushed to any other side before switching modes, turn the cruise control system off, then, perform the steps above again.

      		 ○ ○
      Other Cancellation Conditions

      If any of the following conditions occur during cruise control driving, the cruise control is canceled. However, the set vehicle speed remains in the memory:


      • VSC operates during cruise control driving.

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

      • TRC is off or VSC is off.

      		 ○ ○

      Tech Tips

      ○: Available

      -: Not available

    2. Constant Speed Control Mode


      1. The driving support ECU assembly compares the actual vehicle speed (wheel speed signal from the skid control ECU) 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 EV control ECU, thus controlling the motive force optimally and adjusting the actual vehicle speed to the set vehicle speed.

        A01MA11E01

    3. Deceleration Control Function (Vehicle-to-vehicle Distance Control Mode)


      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 EV control ECU and the skid control ECU. Upon receiving this signal, these ECUs control the motive force and decelerate the vehicle.

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

        A01MACTE01

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

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

        A01MA9DE01

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

        A01MAG5E01

    4. Follow-up Control Function (Vehicle-to-vehicle Distance Control Mode)


      1. Under follow-up control, the driving support ECU assembly transmits a motive force request signal to the EV control ECU and the skid control ECU, so that the vehicle can follow the preceding vehicle while maintaining a proper vehicle-to-vehicle distance in accordance with the vehicle speed. Upon receiving this signal, these ECUs control the motive force in order to effect follow-up control.

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

        A01MAF1E01

    5. Acceleration Control Function (Vehicle-to-vehicle Distance Control Mode)


      1. If the driving support ECU assembly detects that either the preceding vehicle or the driver's own vehicle has changed lanes, a motive force request signal is transmitted to the EV control ECU in order to attain the set vehicle speed. Upon receiving this signal, the EV control ECU controls the motive force in order to perform acceleration control.

        A01MA95E01

    6. Automatic Cancel Control


      1. When any of the conditions listed below occur while the vehicle is in cruise control, the cruise control system is canceled. Then, the following warnings appear for the driver.

        Constant Speed Control Mode
        Description of Malfunction Warning
        Multi-information Display A01MA9T Buzzer A01MADY

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


        • Stop light switch open or short circuit.

        The cruise control 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 main switch.

        		 Cruise Control Malfunction Visit Your Dealer Illuminates - Does not illuminate

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


        • Stop light switch assembly input signal is abnormal.

        • Cancel circuit malfunction.

        The cruise control system is disabled until the power switch is turned on (IG) again.

        		 Cruise Control Malfunction Visit Your Dealer Illuminates Sounds once Does not illuminate

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


        • FC system malfunction.

        The cruise control is disabled until the FC system condition is corrected.

        		 - Does not illuminate - Does not illuminate

        If either of the conditions listed below occurs, the driving support ECU assembly clears the set vehicle speed and cancels the cruise control system. However, the cruise control system and vehicle speed can be set again.


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

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

        		 - Does not illuminate - Illuminates
        Vehicle-to-vehicle Distance Control Mode
        Description of Malfunction Warning
        Multi-information Display A01MA9T Buzzer A01MA5D

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


        • Stop light switch open or short circuit.

        The cruise control 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 main switch.

        		 Cruise Control Malfunction Visit Your Dealer Illuminates Sounds once Does not illuminate

        If any of the conditions listed below occur, the driving support ECU assembly clears the set vehicle speed and cancels 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.

        • Stop light switch assembly input signal is abnormal.

        • Cancel circuit malfunction.

        The cruise control is disabled until the power switch is turned on (IG) again.

        		 Cruise Control Malfunction Visit Your Dealer Illuminates Sounds once Does not illuminate

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


        • FC system malfunction.

        The cruise control is disabled until the FC system condition is corrected.

        		 - Does not illuminate - Does not illuminate

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


        • The millimeter wave radar sensor assembly is dirty.

        The cruise control 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 main switch.

        		 Radar Cruise Control Unavailable Clean Sensor Illuminates Sounds once Does not illuminate

        If either of the conditions listed below occurs, the driving support ECU assembly cancels 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.

        The cruise control 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 main switch.

        		 Radar Cruise Control Unavailable Illuminates Sounds once Does not illuminate

        If the condition listed below occurs, the driving support ECU assembly cancels 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 Illuminates

  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 light (constant speed control mode) or radar cruise control indicator light (vehicle-to-vehicle distance control mode), and cruise SET indicator light. Also, "Cruise Control Malfunction Visit Your Dealer" 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.