GENERAL INFORMATION


In addition to the conventional cruise control system, an adaptive cruise control (ACC) system , which maintains the distance from vehicle travelling in front, has been adopted.

note
  • If vehicle travelling in front accelerates faster than your vehicle’s set speed, your vehicle will be driven at your set speed.
  • If the vehicle travelling in front stops, your vehicle also stops.
  • In the case below, the system will not accelerate or decelerate the vehicle.

    • The vehicle is stationary or too slow.
  • Under the circumstance below, the system cannot detect the vehicle travelling ahead precisely, so may not maintain the distance between the vehicle travelling ahead and your vehicle.

    • The luggage compartment or the rear seat is loaded too heavily.
    • The vehicle is driven on a steep uphill or downhill road.
    • Another vehicle cuts in your lane suddenly (the vehicle travelling in front is not straight ahead of your vehicle).
    • There is mud, ice or snow clinging to the vehicle.
  • Under the circumstances below, the system could not detect the vehicle travelling ahead temporarily or could mistakenly recognise another object as a vehicle. This could activate the warning.

    • Entering/exiting a corner, during cornering, or a lane regulation due to a construction work, etc.
    • Your vehicle position or steering operation is unstable due to a traffic accident or failure.
  • Do not use the ACC system under any of the circumstances below, or it may cause a serious injury.

    • Driving on a congested, tight-bend or winding road.
    • Slippery road covered with ice or snow
    • Under bad weather (rain, snow, fog)
    • There is mud, ice or snow adhered on the sensor.
    • Too steep downhill/uphill road or there is a series of uphill and downhill grades.
    • Too frequent acceleration/deceleration are needed.
    • The approaching vehicle warning sounds too frequently.
    • Being towed or towing another vehicle.
    • Your vehicle is on a dynamometer or free-roller.
  • Protect the sensor against severe impact. Never disassemble the sensor.

Control overview

Constant speed control

The vehicle is driven at a constant speed.

Deceleration and distance-keeping controls


  • If the vehicle travelling ahead decelerates, your vehicle also decelerates to maintain the distance. If the vehicle travelling ahead brakes to a standstill, your vehicle also brakes.
  • If the vehicle travelling ahead accelerates, your vehicle also accelerates within the set vehicle speed.
note The distance between the vehicle travelling ahead and your vehicle can be chosen from three settings on the ACC distance switch.

Acceleration control


  • If vehicle travelling in front accelerates faster than your vehicle’s set speed, your vehicle will accelerate until it reaches your set speed gradually, and then be driven at a constant speed.
  • If the turn-signal lever is operated while the ACC system is active, the system may accelerate the vehicle to assist you in passing a vehicle in front, which reduces the distance between your vehicle and the vehicle in front.

CONSTRUCTION DIAGRAM




COMPONENTS AND FUNCTIONS


Component
 Function
ACC/FCM-ECU
  • ACC system status is changed based on the ACC/cruise control system/adjustable speed limitation control mode and on the signal of switch state sent from engine-ECU.
  • Signals of the ACC system status (OFF, standby, active, temporary fail and system fail) and ACC system status transition request to ATSC-ECU are sent based on the internal ACC system status.
  • Acceleration/deceleration are calculated from the ACC system status, subject vehicle speed and data which the radar detects, and Acceleration/deceleration are sent to ASTC-ECU.
ASTC-ECU
  • The ASTC-ECU controls brake pressure based on signals of acceleration/deceleration and the target deceleration received from ACC/FCM-ECU.
  • ASTC-ECU triggers the stop lamp when the automatic brake is activated.
  • ASTC-ECU internal ACC system status is switched based on basically signal of ACC system status transition request received from ACC/FCM-ECU and sent as signal.
  • Target engine torque is sent to engine-ECU according to the acceleration/deceleration received from ACC/FCM-ECU.
Combination meter
 ACC display screen
 Contents of display and buzzer are changed according to signal of ACC system status, Display request and buzzer request sent from ACC/FCM-ECU when signal of control mode sent from engine-ECU is ACC system ON.
Cruise control switches
 ACC ON/OFF switch
 Power switch for ACC system.
note
  • The system activates by pressing the switch briefly (within 1.5 seconds).
  • The cruise control system activates by pressing the switch for certain period (1.5 seconds or more).
ACC distance switch
 The distance from vehicle travelling in front is set with the distance switch.
RES + switch
 Vehicle speed is set with the RES+ switch and SET- switch.
SET - switch
CANCEL switch
 Cancels the constant speed driving.
A/T-ECU
 Control map is changed from general control map to cruise control system, ACC system control map according to signals of cruise control system control flag, and T/M is controlled by accelerator pedal position sensor which are received from engine-ECU.
Diagnosis connector
 If the M.U.T.-III is connected, the diagnosis code and data list from the ACC/FCM-ECU can be read.
Engine-ECU
  • Signals of state of steering switches (including failure judgement result) are sent.
  • Acceleration/deceleration are controlled according to ACC system target torque received from ASTC-ECU when ACC system mode is ON and ACC system status is active. Engine-ECU has cruise control module as a part of engine-ECU. ACC system target torque which is sent from ASTC-ECU through signal is input to the cruise control module. Cruise control module outputs ACC system target torque to engine-ECU.

Stop lamp relay
 Stop lamp ON/OFF circuit which is driven at automatic brake control by ASTC-ECU is equipped.
Gateway-ECU
 The state of ACC set distance switch is sent.
Steering wheel sensor (SAS)
 Signals of the steering angle and the steering angle velocity are sent.

CONSTRUCTION AND OPERATION



BLOCK DIAGRAM

SYSTEM FUNCTIONS


DISTANCE FUNCTION


During ACC system control, the distance from vehicle travelling ahead can be chosen from three settings.

FAIL-SAFE AND DIAGNOSTIC FUNCTIONS


ACC/FCM-ECU constantly monitors the input and output signals. If an error is detected in the system, ACC/FCM-ECU sends a fail signal and the corresponding display screen. To ease the system inspection, the diagnosis code inspection, data list inspection is available by M.U.T.-III.

RADAR ADJUSTMENT


If the ACC/FCM-ECU is replaced or removed and installed, adjust the radar by using the M.U.T.-III.