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
      Millimeter Wave Radar Sensor Assembly Radiates millimeter radar waves forward, uses the reflected waves to detect the presence of a vehicle ahead, the vehicle-to-vehicle distance, the relative speed and direction then transmits this information to the driving support ECU assembly.
      Forward Recognition Camera Detects lane markers and objects on the road ahead using the image captured by the monocular camera and sends the 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 and forward recognition camera. 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).
      Skid Control Buzzer Assembly Sounds a buzzer when it receives a signal from the driving support ECU assembly to alert the driver that the distance between vehicles is short.
      Cruise Control Switch ON-OFF Button

      • Turns the cruise control system on and off.

      • Vehicle-to-vehicle distance control mode becomes be activated immediately after the main switch is turned on. The mode shifts to constant speed control mode by pressing and holding the button more than 1.5 sec.
      CANCEL Switch A cancel signal is 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.

      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 distance control switch to select the vehicle-to-vehicle distance in three levels: long, middle and short.
      Combination Meter Assembly Cruise Control Indicator

      • Based on a cruise control indicator operation signal sent by the ECM, the combination meter assembly illuminates the cruise control indicator (constant speed control mode) or cruise control indicator (vehicle-to-vehicle distance control mode) 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 ECM, the combination meter assembly turns off the cruise control indicator if a malfunction occurs in the cruise control system.
      Cruise SET Indicator Cruise SET indicator Illuminates when the vehicle speed is set.
      Multi-information Display

      • Displays a warning message to alert the driver in accordance with a signal provided by the ECM.

      • During dynamic radar cruise control operation, the multi-information display receives signals from the ECM in order to display the system conditions.
      Buzzer If the ECM detects automatic cancel or warning signals while the vehicle is operating under cruise control, this buzzer sounds to inform the driver.
      Master Warning Light Comes on when there is a malfunction in the system.
      Steering Sensor Detects the angle and direction of steering and transmits signals to the skid control ECU and driving support ECU assembly.

      Airbag Sensor Assembly


      • Yawrate Sensor

      		 Detects the yawrate of the vehicle and transmits signals to the driving support ECU assembly.
      Stop Light Switch Assembly Detects brake pedal depression and transmits its signal to the ECM.

      Brake Actuator Assembly


      • Skid Control ECU

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

      • Applies the brakes in accordance with signals from the ECM.
      Speed Sensors Detects the wheel speed of each of the 4 wheels.
      ECM

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

      • If the ECM detects a malfunction in the cruise control system, it will store Diagnostic Trouble Codes (DTCs).
      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.
      Park/Neutral Position Switch Assembly Detects the shift lever position and transmits signals to the ECM.

      Transmission Floor Shift Assembly


      • Transmission Control Switch

      • Detects the shift lever position and transmits signals to the ECM.

      • Informs the ECM of driver upshift or downshift operations while the shift lever is in S.
      Accelerator Pedal Sensor Assembly Detects the accelerator pedal depression angle and transmits it to the ECM.
      VSC OFF Switch Detects the VSC OFF or TRC OFF signals and outputs it to the skid control ECU.
      Central Gateway ECU (Network Gateway ECU) Gateway function of CAN communication.

  2. 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 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 valve opening angle. When the actual vehicle speed is lower than the set speed, it uses the throttle motor to increase the throttle valve opening angle. ○ ○
        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.

        		 ○ ○
        The vehicle is being driven at a speed of approximately 50 km/h to 200km/h (30 mph to 125 mph). ○ -
        The vehicle is traveling at a speed within the range of approximately 50 km/h to 180 km/h (30 mph to 110 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 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: 103 → 100 → 95 → 90 → 85 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 km/h or 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 was being driven at the time the switch was operated.

        		 ○ -

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

        • The vehicle will decelerate in increments of approximately 5 km/h or 5 mph for 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: 83 → 85 → 90 → 95 → 100 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 (subsequently pushes the cruise control switch assembly 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 pushing 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 km/h or 1 mph for 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 1 km/h or 1 mph for each time the switch is moved.*1

        • The vehicle will accelerate in increments of approximately 5 km/h or 5 mph for 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 any of the following conditions are met, the cruise control is canceled accordingly.


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

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

        • 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.

        		 ○ ○
        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:


        • Vehicle to vehicle distance control mode becomes be activated immediately after the main switch is turned on. The mode shifts to constant speed control mode by pressing and holding the button more than 1.5 sec.

        		 ○ ○
        Other Cancel Conditions

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


        • VSC operates during cruise control driving.

        • TRC operates for a certain period of time while the cruise control.

        • TRC is off or VSC is off.

        • Engine switch off.

        		 ○ ○
        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. ○ ○

        *1: Except models for Europe

        *2: Models for Europe

        ○: Available

        -: Not Available

    2. Constant Speed Control Mode


      1. The millimeter wave radar sensor assembly and forward recognition camera transmits the information about the vehicle ahead to the driving support ECU assembly and also transmits a millimeter wave radar sensor assembly operation signal to the ECM via the driving support ECU assembly. 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.

        A002603E05

    3. Deceleration Control (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, forward recognition camera 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.

        A0025ZSE03

      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, in order to warn any vehicles behind.

        A0025R7E03

      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.

        A0025X0E03

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


      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 vehicle-to-vehicle distance control switch.

        A0025QPE03

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


      1. If the driving support ECU assembly detects (based on the millimeter wave radar sensor assembly and forward recognition camera ) that either the vehicle ahead or the driver 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.

        A0025TGE03

    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 A00263F Buzzer in the combination meter assembly

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


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

        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.

        Cruise Control

        Malfunction

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        Dealer

        		 Illuminates Sounds

        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 [approximately 40 km/h (25 mph)].

        		 - Does not illuminate -

        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.

        		 - Does not illuminate -

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


        • Malfunction in engine control 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.

        		 - Illuminates -

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


        • 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.

        		 - - -
        Vehicle-to-vehicle Distance Control Mode
        Situation Warning
        Multi-information Display A00263F Buzzer in the combination meter assembly

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


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

        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.

        Cruise Control

        Malfunction

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        Dealer

        		 Illuminates Sounds

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


        • 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 engine switch is turned on (IG) again.

        Cruise Control

        Malfunction

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        Dealer

        		 Illuminates Sounds

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


        • Malfunction in engine control 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.

        		 - Illuminates -

        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 assembly or the emblem are dirty.

        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.

        Radar Cruise

        Control

        Unavailable

        Clean Sensor

        		 Illuminates Sounds

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


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

        • Brake control by the dynamic radar cruise control system is temporarily unavailable.

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

        • A Malfunction in the forward recognition camera.

        • Forward recognition camera temporarily not available.

        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.

        Radar Cruise

        Control

        Unavailable

        		 Illuminates Sounds

        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 [approximately 40 km/h (25 mph)].

        		 - Does not illuminate Sounds twice

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


        • 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.

        		 - - -

  3. 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 "Cruise Control Malfunction Visit Your Dealer" 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. The DTCs can be read when a Global TechStream (GTS) is connected to the DLC3. For details, refer to the Repair Manual.