CRUISE CONTROL SYSTEM


  1. FUNCTION OF MAIN COMPONENTS


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

      Component Function
      Cruise Control Switch ON-OFF Button Turns the cruise control system on and off.
      +RES Switch The accelerate 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 decelerate function and vehicle speed setting signals are output to the ECM when this switch is operated.
      CANCEL Switch A cancel signal is output to the ECM when this switch is operated.
      ECM Controls all functions of the cruise control system in accordance with the signals from switches, sensors and ECUs.
      TCM Performs downshifts and upshifts according to signals from the ECM.
      Brake Actuator Assembly Skid Control ECU

      • Transmits the VSC operation signal to the ECM.

      • Transmits the speed signal to the combination meter assembly.
      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 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.
      Master Warning Light Comes on when there is a malfunction in the system.
      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.
      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 ECM.
      Park/Neutral Position Switch Assembly Detects the shift lever position and transmits signals to the ECM.
      Combination Switch Assembly VSC OFF Switch Detects the VSC OFF signal and outputs it to the skid control ECU.
      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 M.
      Shift Paddle Switch (Transmission Shift Switch Assembly) While the vehicle is being driven in D mode or M mode, this switch outputs a signal to the ECM when the switch is pulled to "+" or "-".
      Stop Light Switch Assembly Detects the brake pedal being depressed and transmits a signal to the ECM.

  2. FUNCTION


    1. The cruise control system has the following control functions:

      Function Outline
      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 control motor to increase the throttle valve opening angle.
      Set Control

      When the following conditions are met and the cruise control switch is moved to the -SET side and released, the ECM stores the vehicle speed and maintains the vehicle constantly at that speed.


      • The cruise control system has been turned on using the ON-OFF button on the cruise control switch.

      • The vehicle is being driven at a speed of approximately 40 km/h (25 mph) or more.
      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 speed control by the cruise control system is operating, speed control by the cruise control system will be canceled automatically. However, the set 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:


      • The vehicle will decelerate.

      • The set vehicle speed will change to the speed at which the vehicle is being driven when the COAST switch (-SET side operation) 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:


      • 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 or 3 mph, the set vehicle speed will change to the speed at which the vehicle is being driven when the switch is pushed.
      Accelerator Control

      When the cruise control switch is held to the +RES side, the vehicle speed and the set vehicle speed change as follows:


      • The vehicle will accelerate.

      • The set vehicle speed will change to the speed at which the vehicle is being driven when the switch is released.
      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 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 3 mph, the set vehicle speed will not change.
      Resume Control When the cruise control is canceled for any reason other than a malfunction (except cancellation by operating the ON-OFF button on the cruise control main switch) and the vehicle speed is more than the low speed limit, the vehicle can be returned to the speed it was traveling at before the cancellation of cruise operation by moving the cruise control main switch to the +RES side. The cruise control mode can be resumed even if the vehicle speed drops below the low speed limit, because the speed in the memory has not been cleared.
      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 accelerator control or resume control, the transmission will shift up after accelerator control or resume control ends.
      Manual Cancel Control

      If any of the following signals are sent to the ECM, cruise control speed control operation is canceled accordingly.


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

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

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

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

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

      If the following condition occurs while the cruise control system is controlling vehicle speed, the speed that is stored in memory is cleared and speed control by the cruise control system is canceled.


      • Stop light switch open or short circuit.

      Furthermore, the master warning light illuminates, the cruise control indicator turns off, and a message indicating a malfunction will be displayed on the multi-information display until the cruise control system is turned off using the cruise control switch. Speed control by the cruise control system is disabled until the cruise control system is turned on again using the ON-OFF button.

      If the following condition occurs while the cruise control system is controlling vehicle speed, the speed that is set in memory is cleared and speed control by the cruise control system is canceled.


      • Malfunction in the engine control system.

      Furthermore, speed control by the cruise control system is disabled until the cruise control system is turned on again using the ON-OFF button.

      If any of the following conditions occurs while the cruise control system is controlling vehicle speed, the speed that is set in memory is cleared and speed control by the cruise control system is canceled.


      • Stop light switch input signal is abnormal.

      • Cancel circuit malfunction.

      • Communication malfunction between the skid control ECU assembly and ECM.

      • Brake control system malfunction.

      Furthermore, the master warning light illuminates, the cruise control indicator turns off, and a message indicating a malfunction will be displayed on the multi-information display until the cruise control system is turned off using the cruise control switch. The operation of speed control by the cruise control system is disabled until the engine switch is turned off.

      If the following condition occurs while the cruise control system is controlling vehicle speed, the speed that is set in memory is cleared and speed control by the cruise control system is canceled.


      • Vehicle speed decreases by 16 km/h (10 mph) or more below the speed at which the cruise control system is set.

      If the following condition occurs while the cruise control system is controlling vehicle speed, speed control by the cruise control system is canceled.


      • Vehicle speed decreases below the low speed limit (approximately 40 km/h [25 mph]).
      Other Cancel Items

      • VSC is activated.

      • TRC is activated for a period of time.

      • When the VSC or TRC system is turned off by pressing the VSC OFF switch.

  3. DIAGNOSIS


    1. If a malfunction occurs in the cruise control system during cruise control operation, the ECM cancels cruise control operation, illuminates the master warning light and turns off the cruise control indicator and cruise SET indicator. At this time, a warning message is displayed on the multi-information display. The ECM stores the malfunction in the form of a Diagnostic Trouble Code (DTC).

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