DYNAMIC RADAR CRUISE CONTROL SYSTEM


  1. General

    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

    Control Outline Mode
    A B
    Constant Speed Control The ECM compares the actual vehicle speed and the set speed. If the vehicle speed is higher than the set speed, the ECM uses the throttle control motor to decrease the throttle opening. If the actual vehicle speed is lower than the set speed, the ECM uses the throttle control motor to increase the throttle opening. ○ ○
    Deceleration Control Effects 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 effecting deceleration control, the 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

    While this system fulfills the following conditions, the cruise control switch is pressed to the -SET side and released when the ON/OFF button on the cruise control switch has been pressed to turn the system on, the ECM stores the vehicle speed, illuminates the cruise control SET indicator light on the combination meter assembly, and maintains the vehicle constantly at that speed.


    • The shift lever is in D.

    • The shift lever is moved to the S mode, and shift range is 4th, 5th or 6th.

    		 ○ ○

    The vehicle is running within the following speed range:


    • Approx. 50 to 200 km/h (30 to 125 mph)

    		 ○ -

    The vehicle is running within the following speed range:


    • Approx. 50 to 170 km/h (30 to 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 approx. 40 km/h (25 mph). The cruise control cannot be set below that speed. If the vehicle speed drops below that speed while running in the cruise control, the cruise control will be canceled automatically. However, the set vehicle speed in the memory is kept. ○ ○
    Coast Switch Control While the cruise control switch is held to the -SET side, the vehicle speed and the set speed change, in accordance with the mode as follows: ○ ○

    • The vehicle decelerates constantly.

    • The set speed changes to the speed at which the switch was turned off.

    		 ○ -

    • The vehicle setting speed decreases in increments of 5 km/h or 5 mph.


      • [Example: 57 → 55 → 50 km/h, 57 → 55 → 50 mph]

    • The vehicle decelerates rapidly due to ETCS-i.

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

    • The vehicle will decelerate in increments of approx. 1.6 km/h (1 mph) for each time the switch was pressed.

    • However, if the difference between the actual vehicle speed and the set speed is greater than 5 km/h (3 mph), the set 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 approx. 5 km/h (5 mph) for each time the switch was pressed.

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

    • The vehicle will accelerate constantly.

    • The set speed changes to the speed at which the switch was turned off.

    		 ○ -

    • The set speed increases in increments 5 km/h or 5 mph.


      • [Example: 52 → 55 → 60 km/h, 52 → 55 → 60 mph]

    • The vehicle will accelerate to the speed that was set at the time the switch was released.


      • However, only the set speed will change during follow-up control.

    		 - ○
    Resume Control When the driver pushes the cruise control switch to the +RES side after the vehicle speed has exceeded the low speed limit, the cruise control resumes operation to reach the vehicle speed that was set at the time the driver canceled cruise control. ○ ○

    • Even if the vehicle speed drops below the low speed limit, resume can be performed when the vehicle speed exceeds the low speed limit.

    • If the vehicle ahead changes driving lanes during follow-up control, the vehicle speed is gradually increased to the set 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 pushed momentarily (approx. 0.6 sec.) to the +RES side, the vehicle speed and the set speed change in accordance with the mode as follows: ○ ○

    • The vehicle will accelerate in increments of approx. 1.6 km/h (1 mph) for each time the switch was pressed.

    • However, if the difference between the actual vehicle speed and the set speed is greater than 5 km/h (3 mph), the set speed changes to the speed as which the vehicle was being driven at the time the switch was operated.

    		 ○ -

    • The vehicle will accelerate in increments of approx. 5 km/h (5 mph) for each time the switch was pressed.

    		 - ○
    Shift Down Control When the vehicle is cruising uphill, shift down control may be performed by the Electronic Control Transmission (ECT). The ECM transmits the shift up request signal to the ECT ECU when the ECM judges the end of cruising uphill based on the throttle valve angle. ○ ○
    Manual Cancel Control

    If any of the following conditions is met, the cruise control will be canceled:


    • A stop light switch on signal is sent to the ECM (the brake pedal is depressed).

    • The shift lever is moved from D to N.

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

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

    • An ON/OFF button off signal is sent to the ECM.

    • A VSC operation signal is sent to the ECM.

    		 ○ ○
    Automatic Cancel Control When an automatic cancel signal is sent to the ECM, the cruise control operation is canceled. At this time, the warning method and the control resumption condition vary in accordance with the cancel signal. ○ ○
    Mode Switching Control

    The following operations switch the modes:


    1. ON/OFF button on the cruise control switch is on (starts in the vehicle-to-vehicle distance control mode).

    2. Cruise control switch is held to the MODE side (approx. 1 second or more).

    If the switch is pushed to any other side before switching modes, switch the cruise control system off, then perform steps 1) and 2) again.

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

  2. Constant Speed Control


    1. General


      • In the constant speed control mode, the constant speed control is effected by the ECM.

      • In the vehicle-to-vehicle distance control mode, the constant speed control is effected by the millimeter wave radar sensor and distance control ECU.

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

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

    A01W63KE01

  3. Deceleration Control


    • The distance control ECU 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.

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

      A01W6BBE01

    • If the distance control ECU 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.

    • 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 inform anyone who might be following the vehicle.

      A01W71NE01

    • If further deceleration is necessary after the stop light is illuminated, the skid control ECU sounds the VSC warning buzzer based on the request signal from the distance control ECU to urge the driver to depress the brake pedal.

      A01W71UE01

  4. Follow-up Control


    • After effecting deceleration control, the distance control ECU transmits a request signal to the ECM so that the vehicle can follow the vehicle ahead while maintaining the proper vehicle-to-vehicle distance in accordance with the vehicle speed. Upon receiving this signal, the ECM regulates the throttle in order to effect follow-up control.

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

      A01W6LYE01

  5. Acceleration Control

    If the distance control ECU 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 effect acceleration control.

    A01W5WSE01

  6. Automatic Cancel Control

    If any of the conditions listed below occurs while the vehicle is in cruise control (A: constant speed control mode, B: vehicle-to-vehicle distance control mode), the cruise control will be canceled. Then, the following warning will be issued:


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

    2. Master warning light illuminates.

    3. Multi buzzer sounds.

    4. Cruise control main indicator light turns off.

    Mode Description of Malfunction Warning
    A and B

    If any of the conditions listed below occurs, the ECM clears the set speed and cancels the cruise control:


    • Malfunction of the vehicle speed signal

    • An open or short circuit in the stop light switch

    The cruise control is prohibited until the conditions are restored or the cruise control system is turned off and back on again using the ON/OFF button on the cruise control switch.

    1. "CHECK CRUISE CONTROL SYSTEM"

    2. Illuminates

    3. Sounds Once

    4. Turns Off

    If the condition below occurs, the ECM clears the set speed and cancels the cruise control:


    • Malfunction in the ETCS-i

    The cruise control is prohibited until the condition is restored or the cruise control system is turned off and back on again using the ON/OFF button on the cruise control switch.

    1. -

    2. -

    3. -

    4. Turns Off

    If any of the conditions listed below occurs, the ECM clears the set speed and cancels the cruise control:


    • Malfunction of the stop light switch input signal circuit

    • Malfunction of the cancel circuit

    The cruise control is prohibited until the power source is turned on again.

    1. "CHECK CRUISE CONTROL SYSTEM"

    2. Illuminates

    3. Sounds Once

    4. Turns Off
    A

    If the condition below occurs, the ECM cancels the cruise control while retaining the set speed in its memory:


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

    1. -

    2. -

    3. -

    4. Turns Off
    B

    If the condition below occurs, the ECM cancels the cruise control while retaining the set speed in its memory:


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

    1. -

    2. -

    3. Sounds Twice

    4. Turns Off
    A

    If the condition below occurs, the ECM clears the set speed and cancels the cruise control:


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

    1. -

    2. -

    3. -

    4. Turns Off
    B

    If any of the conditions listed below occurs, the ECM clears the set speed and cancels the cruise control:


    • Malfunction of the millimeter wave radar sensor

    • Displacement of the axis of the millimeter wave radar sensor

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

    The cruise control is prohibited until the engine switch is turned on (IG) again.

    1. "CHECK CRUISE CONTROL SYSTEM"

    2. Illuminates

    3. Sounds Once

    4. Turns Off

    If the condition below occurs, the ECM cancels the cruise control while retaining the set speed in its memory:


    • The millimeter wave radar sensor is dirty.

    The cruise control is prohibited until the condition is remedied or the cruise control system is turned off and back on again using the ON/OFF button on the cruise control switch.

    1. "CLEAN RADAR SENSOR"

    2. Illuminates

    3. Sounds Once

    4. Turns Off

    If any of the conditions listed below occurs, the ECM cancels the cruise control while retaining the set vehicle speed in its memory:


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

    • When the 2nd start control mode is selected.

    The cruise control is prohibited until the conditions are remedied or the cruise control system is turned off and back on again using the ON/OFF button on the cruise control switch.

    1. "CRUISE CONTROL NOT AVAILABLE"

    2. Illuminates

    3. Sounds Once

    4. Turns Off

  7. Diagnosis

    If a malfunction occurs in the dynamic radar cruise control system, the ECM actuates the automatic cancel control and turns off the cruise main indicator light or the radar cruise indicator light. Then, the multi-information display in the combination meter displays "CHECK CRUISE CONTROL SYSTEM" warning message to inform the driver of a malfunction during cruise control. At this time, the ECM memorizes the malfunction in the form of 5-digit Diagnostic Trouble Codes (DTCs).


    • The 5-digit DTCs can be read by connecting the Global TechStream (GTS) to the DLC3. For details, see the Repair Manual.