PRE-COLLISION SYSTEM DESCRIPTION
The pre-collision system uses the pre-collision warning control, pre-collision brake assist control and pre-collision braking control to help avoid a collision or reduce the impact if it determines that the possibility of a collision is high or a collision is unavoidable based on the position and relative speed of a preceding vehicle.
The operation of this system can be turned off and on using the setting screen of the multi-information display.
Tech Tips
When the pre-collision system is turned off, the PCS warning light in the combination meter assembly will illuminate.
PRE-COLLISION SYSTEM SENSOR DESCRIPTION
The millimeter wave radar sensor assembly and forward recognition camera detect the position and relative speed of preceding vehicles. This information is sent to the millimeter wave radar sensor assembly to determine if the possibility of a collision is high or a collision is unavoidable.
FUNCTION OF MAIN COMPONENTS
| COMPONENTS | FUNCTION |
|---|---|
| Millimeter Wave Radar Sensor Assembly |
|
| Forward Recognition Camera | Captures images of the area in front of the vehicle and processes them to detect preceding vehicles and sends information to the millimeter wave radar sensor assembly. |
| Yaw Rate Sensor (Airbag Sensor Assembly) | Detects the yaw rate and acceleration of the vehicle and sends signals to the millimeter wave radar sensor assembly. |
| Steering Sensor | Detects the steering angle and direction, and sends signals to the millimeter wave radar sensor assembly. |
| Vehicle Speed Sensor | Detects the wheel speed and sends signals to the skid control ECU (brake actuator assembly). |
| Stop Light Switch Assembly |
|
| Steering Pad Switch Assembly |
|
| VSC OFF Switch | Disables the pre-collision brake assist control and pre-collision braking control if pressed and held. |
| Skid Control ECU (Brake Actuator Assembly) |
|
| Combination Meter Assembly |
|
| Main Body ECU (Multiplex Network Body ECU) | Sends vehicle destination country information to the millimeter wave radar sensor assembly. |
| Headup Display (Meter Mirror Sub-assembly)* | Displays "BRAKE!" on the headup display when the pre-collision warning control is being performed. |
*: w/ Headup Display System
OUTLINE OF PRE-COLLISION SYSTEM
Pre-collision Warning:
When the system determines that the possibility of a frontal collision is high, a buzzer will sound and a warning message will be displayed on the multi-information display to urge the driver to take evasive action.
Pre-collision Brake Assist:
When the system determines that the possibility of a frontal collision is high, the system applies greater braking force in relation to how strongly the brake pedal is depressed.
Pre-collision Braking:
When the system determines that the possibility of a frontal collision is high, the system warns the driver. If the system determines that the possibility of a collision is extremely high, the brakes are automatically applied to help avoid the collision or reduce the collision speed.
Tech Tips
The vehicle may creep after the pre-collision braking function has operated, the driver should depress the brake pedal as necessary.
If the accelerator pedal is being depressed strongly or the steering wheel is being turned, the system may determine that the driver is taking evasive action and possibly prevent the pre-collision braking function from operating.
PRE-COLLISION SYSTEM CONTROL OPERATION
| Control | Operating Condition | Transmitting ECU | Receiving ECU | Part Operated |
|---|---|---|---|---|
| Pre-collision warning | Possibility of a collision is high | Millimeter Wave Radar Sensor Assembly | Combination Meter Assembly |
|
| Pre-collision brake assist |
|
Millimeter Wave Radar Sensor Assembly |
|
|
| Pre-collision braking | Possibility of a collision is high | Millimeter Wave Radar Sensor Assembly |
|
|
PRE-COLLISION SYSTEM OPERATION CONDITIONS
CAUTION:
Always observe the legal speed limit when driving on public roads.
Pre-collision Warning
The pre-collision system is ON.
Vehicle speed is between approximately 15 and 180 km/h (10 and 110 mph).
The relative speed to a preceding vehicle is approximately 10 km/h (7 mph) or more.
Pre-collision Brake Assist (PBA)
The pre-collision system is ON.
The VSC is enabled.
Vehicle speed is between approximately 30 and 180 km/h (20 and 110 mph).
The relative speed to a preceding vehicle is approximately 30 km/h (20 mph) or more.
Pre-collision Braking (PB)
The pre-collision system is ON.
The VSC is enabled.
Vehicle speed is between approximately 15 and 180 km/h (10 and 110 mph).
The relative speed to a preceding vehicle is approximately 10 km/h (7 mph) or more.
Conditions under which the system may operate even if there is no possibility of a collision
In some situations such as the following, the system may determine that there is a possibility of a frontal collision and operate.
When passing a vehicle
When changing lanes while overtaking a preceding vehicle.
When overtaking a preceding vehicle that is changing lanes.
When overtaking a preceding vehicle that is making a left/right turn.
When passing a vehicle in an oncoming lane that is stopped to make a right/left turn.
When driving on a road where relative location of the vehicle to a vehicle ahead in an adjacent lane may change, such as on a winding road.
When rapidly closing on a vehicle ahead.
If the front of the vehicle is raised or lowered, such as when the road surface is uneven or undulating.
When approaching objects on the roadside, such as guardrails, utility poles, trees or walls.
When there is a vehicle or object by the roadside at the entrance of a curve
When driving on a narrow path surrounded by a structure, such as in a tunnel or on an iron bridge.
When there is a metal object (manhole cover, steel plate, etc.), steps, or a protrusion on the road surface or roadside.
When passing through a place with a low structure above the road (low ceiling, traffic sign, etc.).
When passing under an object (billboard, etc.) at the top of an uphill road.
When rapidly closing on an electric toll gate barrier, parking area barrier or other barrier that opens and closes.
When using an automatic car wash.
When driving through or under objects that may contact the vehicle, such as thick grass, tree branches or a banner.
When the vehicle is hit by water, snow, dust, etc. from a vehicle ahead.
When driving through steam or smoke.
When there are patterns or paint on the road or a wall that may be mistaken for a vehicle
When driving near an object that reflects radio waves, such as a large truck or guardrail.
When driving near a TV tower, broadcasting station, electric power plant, or other location where strong radio waves or electrical noise may be present.
Situations in which the system may not operate properly
In some situations such as the following, a vehicle may not be detected by the millimeter wave radar sensor assembly and forward recognition camera, preventing the system from operating properly:
If an oncoming vehicle is approaching the vehicle.
If a vehicle ahead is a motorcycle or bicycle.
When approaching the side or front of a vehicle.
If a preceding vehicle has a small rear end, such as an unloaded truck.
If a preceding vehicle has a low rear end, such as a low bed trailer.
If a vehicle ahead is carrying a load which protrudes past its rear bumper.
If a vehicle ahead has extremely high ground clearance.
If a vehicle ahead is irregularly shaped, such as a tractor or side car.
If the sun or other light is shining directly on a vehicle ahead.
If a vehicle cuts in front of the vehicle or emerges from beside a vehicle.
If a vehicle ahead makes an abrupt maneuver (such as sudden swerving, acceleration or deceleration).
When suddenly cutting behind a preceding vehicle.
When a vehicle ahead is not directly in front of the vehicle.
When driving in inclement weather such as heavy rain, fog, snow or a sandstorm.
When the vehicle is hit by water, snow, dust, etc. from a vehicle ahead.
When driving through steam or smoke.
When driving in a place where the surrounding brightness changes suddenly, such as at the entrance or exit of a tunnel.
When a very bright light, such as the sun or the headlights of oncoming traffic, shines directly into the forward recognition camera.
When the surrounding area is dim, such as at dawn or dusk, or while at night or in a tunnel.
After the engine has started the vehicle has not been driven for a certain amount of time.
While making a left/right turn and for a few seconds after making a left/right turn.
While driving on a curve and for a few seconds after driving on a curve.
If the vehicle is skidding.
If the front of the vehicle is raised or lowered.
If the wheels are misaligned.
If a wiper blade is blocking the forward recognition camera.
The vehicle is wobbling.
The vehicle is being driven at extremely high speeds.
When driving on a hill.
If the millimeter wave radar sensor assembly or forward recognition camera is misaligned.
In some situations such as the following, sufficient braking force may not be obtained, preventing the system from performing properly:
If the braking functions cannot operate to their full extent, such as when the brake parts are extremely cold, extremely hot or wet.
If the vehicle is not properly maintained (brakes or tires are excessively worn, improper tire inflation pressure, etc.).
When the vehicle is being driven on a gravel road or other slippery surface.
If the PCS warning light flashes or illuminates and a warning message is displayed on the multi-information display
Tech Tips
For details on the operation of the PCS warning light and displayed warning messages, refer to Diagnosis System.
The pre-collision system may be temporarily unavailable or there may be a malfunction in the system.
In the following situations, the warning light will turn off, the message will disappear and the system will become operational when normal operating conditions return:
When the millimeter wave radar sensor assembly or forward recognition camera or the area around either sensor is hot, such as in the sun.
When the millimeter wave radar sensor assembly or forward recognition camera or the area around either sensor is cold, such as in an extremely cold environment.
When the millimeter wave radar sensor assembly or front grille emblem is dirty or covered with snow, etc.
When the part of the windshield glass in front of the forward recognition camera is fogged up or covered with condensation or ice.
If the forward recognition camera is obstructed, such as when the hood is open or a sticker is attached to the windshield glass near the forward recognition camera.
When the millimeter wave radar sensor assembly is performing beam axis alignment correction after detecting a misaligned beam axis.
If VSC is disabled
If VSC is disabled, the pre-collision brake assist and pre-collision braking functions are also disabled.
The PCS warning light will turn on and "VSC Turned Off Pre-collision Brake System Unavailable" will be displayed on the multi-information display.