DYNAMIC RADAR CRUISE CONTROL SYSTEM DETAILS


  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 the control mode, between the constant speed control mode and vehicle-to-vehicle distance mode.
      CANCEL Switch A cancel signal can be output to the ECM when this switch is operated.
      RES/+ Switch The acceleration function and resuming of a preset speed can be performed by operating this switch. A signal is output to the ECM when this switch is operated.
      SET/- Switch The deceleration function and vehicle speed setting resume signals are output to the ECM when this switch is operated.
      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 three levels: long, middle, and short.
      Stop Light Switch Assembly Detects brake pedal depression and transmits its signal to the ECM.
      Windshield Wiper Switch Assembly Transmits the windshield wiper switch assembly information to the driving support ECU assembly.
      Millimeter Wave Radar Sensor Radiates millimeter radar waves forward, uses the reflected waves to detect the presence of a vehicle 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 While the system is in vehicle-to-vehicle distance control mode, the driving support ECU assembly detects the vehicle ahead based on signals from the millimeter wave radar sensor. Then, the driving support ECU assembly calculates the acceleration or deceleration rate required in order to attain the target vehicle-to-vehicle distance, and outputs a request signal to the ECM and/or skid control ECU (brake actuator assembly).
      Combination Meter Assembly Transmits the vehicle speed signal (SPD) to the ECM.
      Cruise Main Indicator Light Comes on when constant speed control mode is entered.
      Radar Cruise Control Indicator Light Comes on when the cruise main switch ON-OFF button is pressed to start the cruise control system.
      Master Warning Light Comes on when there is a malfunction in the system.
      Buzzer If the ECM or 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 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 Sensor (Spiral Cable with Sensor Sub-assembly) Detects the angle and direction of steering and transmits signals to the skid control ECU assembly and driving support ECU assembly.
      Yawrate Sensor Detects the yaw rate of the vehicle and transmits signals to the skid control ECU assembly and driving support ECU assembly.
      Rain Sensor This sensor detects raindrops, when the wipers operate HI speed, the rain sensor requests the ECM to provide a cruise control cancel signal.
      Brake Actuator Assembly Skid Control ECU

      • While the system is operating in vehicle-to-vehicle distance control mode, the skid control ECU assembly operates the brake actuator in accordance with the brake request signal received from the ECM.

      • Applies the brakes in accordance with signals from the skid control ECU.
      ECM

      • Controls the dynamic radar cruise control system in accordance with signals from the switches, sensors, skid control ECU assembly and driving support ECU assembly.

      • If the ECM detects a malfunction in the cruise control system, it will store Diagnostic Trouble Codes (DTCs).
      Headup Display Unit (Combination Meter Mirror ECU) Displays a warning message on the windshield to inform or warn the driver of the system condition in accordance with signals from the driving support ECU assembly.
      Main Body ECU (Multiplex Network Body ECU) Transmits the SNOW signal to the ECM.

  2. SYSTEM CONTROL


    1. The driving support ECU assembly, millimeter wave radar sensor and ECM control this system.

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

    3. As in the cruise control system, the constant speed control mode is controlled by the ECM, which outputs signals to the throttle control motor and the TCM.

      A019PUIE02

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

      A019QA9E03

    Tech Tips

    An SST is used if radar axis adjustment is needed. For details, refer to the Repair Manual.

  3. FUNCTION


    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 The ECM compares the actual vehicle speed and the set speed and if the vehicle speed is lower than the set speed, it uses the throttle motor to increase the throttle opening. ○ ○
        In constant speed control mode, constant speed control is performed by the ECM in the same way as conventional cruise control. ○ -
        In vehicle-to-vehicle distance control mode, constant speed control is performed by the millimeter wave radar sensor and driving support ECU assembly. - ○
        Deceleration Control Performs throttle control 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 equals 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 in accordance with the 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 following conditions are met, and the cruise control switch is pressed to the -/SET side and released, the ECM stores the vehicle speed and maintains the vehicle constantly at the current speed.


        • The cruise control system is on.

        • The shift lever is in D or the shift lever is in S with 4th, 5th, or 6th shift range selected.

        		 ○ ○
        The vehicle is traveling at a speed of about 50 km/h (30 mph) or more. ○ -
        The vehicle is traveling at a speed within the range of 50 to 170 km/h (30 to 106 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 approx. 40 km/h (25 mph). The cruise control cannot be set below that speed. If the vehicle speed drops below that speed while driving using cruise control, the cruise control will be canceled automatically. The set vehicle speed is kept in memory. ○ ○
        COAST Switch Control While 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: 82 →80 →75 km/h (mph)]

        • The vehicle decelerates rapidly due to ETCS-i. The vehicle will remain at the speed that the vehicle is traveling at when the COAST 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) 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 or 5 mph, the set vehicle speed will change to the speed at which the vehicle was being driven at the time the switch was operated.

        		 ○ -

        • The vehicle will decelerate in increments of approximately 5km/h or 5 mph each time the switch is moved.*1

        • The vehicle will decelerate in increments of approximately 1 km/h or 1 mph each time the switch is moved.*2

        		 - ○
        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: 62 →65 →70 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 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.

        		 ○ ○
        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) each time the switch was 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 or 5 mph each time the switch is moved.*1

        • The vehicle will accelerate in increments of approximately 1 km/h or 1 mph each time the switch is moved.*2

        		 - ○
        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. ○ ○
        Manual Cancel Control

        If one of the following conditions are met, the cruise control is canceled accordingly.


        • Shift lever is moved from D to N.

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

        • When 1st, 2nd or 3rd shift range is selected in D position by shift paddle switch.*3

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

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

        • Cruise control switch (ON-OFF button) off signal sent to the ECM.

        • SNOW mode signal sent to the ECM.

        • VSC operation signal sent to the ECM.

        		 ○ ○
        Automatic Cancel Control When an automatic cancel signal is sent to the ECM, cruise control operation is canceled. At this time, the type of warning sent to the driver and the control resumption condition varies according to the cancel signal. ○ ○
        Mode Switching Control

        The following operations switch modes:


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

        • The cruise control switch is held to the MODE side. (for approx. 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.

        		 ○ ○
        Diagnosis If a malfunction occurs in the dynamic radar cruise control system during cruise control operation, the ECM cancels cruise control and memorizes information related to the malfunction. ○ ○

        Tech Tips

        ○: Available

      • -: Not Available

      • *1: Models for Europe

      • *2: Models for G.C.C. countries

      • *3: F SPORT

    2. Constant Speed Control in Vehicle-to-vehicle Distance Control

      The millimeter wave radar sensor transmits the information about the vehicle ahead to the driving support ECU assembly and also transmits a millimeter wave radar sensor operation signal to the ECM. The driving support ECU assembly transmits this signal to the ECM. The ECM compares the set vehicle speed and the actual vehicle speed, and performs constant speed control by regulating the throttle in order to attain the set vehicle speed.

      A019PUSE02

    3. Deceleration Control


      1. The driving support ECU assembly calculates the target deceleration rate in accordance with signals from the millimeter wave radar sensor, and transmits a deceleration request signal to the ECM. Upon receiving this signal, the ECM closes the throttle valve in order to cause the vehicle to decelerate.

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

        A019PVDE02

      3. If the driving support ECU assembly determines that further deceleration is necessary, it transmits a brake request signal to the ECM. Upon receiving this signal, the ECM transmits a brake request signal to the skid control ECU. The skid control ECU then controls 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 outputs a stop light illumination request signal to the stop light control relay, in order to warn any vehicles behind.

        A019PT5E02

      5. If the vehicle is not decelerating adequately, the driving support ECU assembly sounds a skid control buzzer assembly to prompt the driver to apply the brakes.

        A019Q9KE02

    4. Follow-up Control


      1. After performing deceleration control, the driving support ECU assembly transmits a request signal to the ECM so that the vehicle can follow the vehicle ahead while maintaining the proper vehicle-to-vehicle distance according to the vehicle speed. Upon receiving this signal, the ECM regulates the throttle in order to perform follow-up control.

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

        A019Q4VE02

    5. Acceleration Control

      If the driving support ECU assembly detects (based on the millimeter wave radar sensor) that either the vehicle ahead or own vehicle has changed lanes, an acceleration request signal is transmitted to the ECM in order to attain the set vehicle speed. Upon receiving this signal, the ECM regulates the throttle in order to perform acceleration control.

      A019PZSE02

    6. Automatic Cancel Control

      If one of the conditions listed below occurs while the vehicle is being driven using cruise control, the cruise control will be canceled. Then, the following warning items will appear for the driver.


      1. Warning message is displayed on the multi-information display.

      2. Master warning light.

      3. Buzzer sounds.

        Constant Speed Control Mode:
        Description of Malfunction Warning

        If either of the conditions listed below occurs, the ECM clears the set vehicle speed and cancels the cruise control.


        • A malfunction of the vehicle speed signal (SPD).

        • An open or short circuit in the stop light switch.

        Cruise control is prohibited until the normal operating conditions are met or the cruise control system is turned off and back on again using the ON-OFF button on the cruise control main switch.

        1. "CHECK CRUISE CONTROL SYSTEM"

        2. Illuminates

        3. Sounds Once

        If the following condition occurs, the ECM cancels the cruise control while retaining the set vehicle speed in its memory.


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

        1. -

        2. -

        3. -

        If the following condition occurs, the ECM 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.

        1. -

        2. -

        3. -

        If the following condition occurs, the ECM clears the set vehicle speed and cancels the cruise control.


        • A malfunction in the ETCS-i.

        Cruise control is prohibited until the normal operating conditions are met or the cruise control system is turned off and back on again using the ON-OFF button on the cruise control main switch.

        1. -

        2. -

        3. -
        Vehicle-to-Vehicle Distance Control Mode:
        Description of Malfunction Warning

        If one of the conditions listed below occurs, the ECM clears the set vehicle speed and cancels the cruise control.


        • A malfunction of the vehicle speed signal (SPD).

        • Millimeter wave radar sensor and driving support ECU assembly region code mismatch is detected.

        • An open or short circuit in the stop light switch.

        Cruise control is prohibited until the normal operating conditions are met or the cruise control system is turned off and back on again using the ON-OFF button on the cruise control main switch.

        1. "CHECK CRUISE CONTROL SYSTEM"

        2. Illuminates

        3. Sounds Once

        If the following condition occurs, the ECM cancels the cruise control while retaining the setting vehicle speed in its memory.


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

        1. -

        2. -

        3. -

        If one of the following conditions occurs, the ECM clears the set vehicle speed and cancels the cruise control.


        • A malfunction of the millimeter wave radar sensor.

        • Displacement of the axis of the millimeter wave radar sensor.

        • A malfunction in the dynamic radar cruise control system other than those given above.

        Cruise control is prohibited until the normal operating conditions are met or the cruise control system is turned off and back on again using the ON-OFF button on the cruise control main switch.

        1. "CHECK CRUISE CONTROL SYSTEM"

        2. Illuminates

        3. Sounds Once

        If the following condition occurs, the ECM cancels the cruise control while retaining the set vehicle speed in its memory.


        • The millimeter wave radar sensor is dirty.

        Cruise control is prohibited until the normal operating conditions are met or the cruise control system is turned off and back on again using the ON-OFF button on the cruise control main switch.

        1. "CLEAN RADAR SENSOR"

        2. Illuminates

        3. Sounds Once

        If one of the following conditions occurs, the ECM cancels the cruise control while retaining the set vehicle speed in its memory.


        • The wipers operate at HI speed (including AUTO mode).

        • The ETC-S mode is in SNOW mode.

        • The measurement becomes extremely unstable due to poor weather conditions.

        Cruise control is prohibited until the normal operating conditions are met or the cruise control system is turned off and back on again using the ON-OFF button on the cruise control main switch.

        1. "CRUISE CONTROL NOT AVAILABLE"

        2. Illuminates

        3. Sounds Once

        If the following condition occurs, the ECM clears the set vehicle speed and cancels the cruise control.


        • A malfunction in the ETCS-i.

        Cruise control is prohibited until the normal operating conditions are met or the cruise control system is turned off and back on again using the ON-OFF button on the cruise control main switch.

        1. -

        2. -

        3. -

  4. CONSTRUCTION


    1. Cruise Control Main Switch


      1. The cruise control main switch consists of the ON-OFF button, and RES/+, MODE, SET/- and CANCEL switches. RES/+, MODE, SET/- and CANCEL switches are operated by moving the lever in the 4 directions indicated.

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

        A019Q7JE01
        *1 Cruise Control Main Switch *2 ON/OFF Button
        *a ON/OFF *b +/RES
        *c MODE *d -/SET
        *e CANCEL - -

    2. Distance Control Switch


      1. While the vehicle is being driven in vehicle-to-vehicle distance control mode, the vehicle-to-vehicle distance setting can be changed as follows each time the distance control switch is pressed; long → middle → short.

        A019PWME01
        *1 Distance Control Switch - -

      2. If the engine switch is turned off and back on (IG), the system will default to "long".

      3. The vehicle-to-vehicle distance is set as follows:

        Mode Vehicle-to-Vehicle Distance*
        Long Approx. 50 m (165 ft)
        Middle Approx. 40 m (125 ft)
        Short Approx. 25 m (80 ft)

        *: While driving at a speed of 80 km/h (50 mph).

    3. Millimeter Wave Radar Sensor


      1. The millimeter wave radar sensor consists of a millimeter wave radar circuit, signal processing circuit, and CPU.

      2. The millimeter wave radar circuit consists of one transmission antenna and 5 reception antennas.

      3. The millimeter wave radar outputs waves when the vehicle speed is above 0 km/h (0 mph), and not when the vehicle speed is at 0 km/h (0 mph). The millimeter wave radar uses frequencies in the 76 GHz band.

      4. The reception antennas receive the millimeter wave radar waves that have been reflected.

      5. The signal processing circuit detects the distance, relative speed, and the direction of the object by generating millimeter wave radar waves and calculating the signals received by the reception antennas. Then, it transmits this information to the driving support ECU assembly.

        A019PUUE02

      6. The distance to the object, azimuth (horizontal angle), and relative speed are calculated from the information that is provided by the reflection millimeter wave radar as described below.

        Distance Calculated from the length of time that has elapsed from the time the waves of the millimeter wave radar have been emitted, until the waves reflected by the millimeter wave radar are received.
        Azimuth Calculated from the angle of the waves reflected by the millimeter wave radar that have been received.
        Relative Speed Calculated by utilizing the changes (Doppler effect*) that occur in the frequencies of the reflected millimeter wave radar waves.

        • *: The Doppler effect causes the observer to perceive the radio wave emitted by a moving object to be of higher frequencies as it approaches, and to be of lower frequencies as it recedes. This phenomenon is created because when an object is located far away, the radio waves are perceived at higher frequencies than those of the radio source.

          A019Q6NE01

  5. OPERATION


    1. Combination Meter Assembly


      1. The combination meter assembly uses a master warning light, cruise main indicator light, radar cruise main indicator light, buzzer, and multi-information display to provide the driver with dynamic radar cruise control system warnings and indications.

      2. The multi-information display displays the set vehicle speed, vehicle ahead mark, and a warning message.

      3. Examples are shown below for the illumination or display of each indicator light, warning light or multi-information display.

        Mode Condition Multi-information Display Cruise Main Indicator Light Master Warning Light Buzzer
        Constant Speed Control Being Controlled A019PZE Illuminates - -
        Vehicle-to-vehicle Distance Control Set Standby A019PTW Illuminates - -
        Under Constant Speed Control (No Vehicle Ahead) A019PR4E01 Illuminates - -
        Under Follow-up Control (Vehicle Ahead) A019PSZE01 Illuminates - -
        Deceleration Control/ Vehicle Approach Warning (Vehicle Ahead)*1 A019Q7CE01 Illuminates - Sounds Continuously
        System Failure Millimeter wave radar sensor is dirty. A019Q6S - Illuminates Sounds Once
        Poor Weather Condition A019PNF - Illuminates Sounds Once
        System Check*2 A019PW7 - Illuminates Sounds Once
        Beam Axis Adjustment A019Q2S - - -

        • *1: Displayed on the headup display also for vehicles with the navigation system.

        • *2: When a Diagnostic Trouble Code (DTC) is memorized.

  6. DIAGNOSIS


    1. If a malfunction occurs in the dynamic radar cruise control system during cruise control operation, the ECM automatically cancels the cruise control, illuminates the master warning light, sounds a buzzer and displays "CHECK CRUISE CONTROL SYSTEM" on the multi-information display to inform the driver of the malfunction. At this time, the ECM memorizes the malfunction in the form of 5-digit Diagnostic Trouble Codes (DTCs).

    2. DTCs can be read when an intelligent tester is connected to DLC3.