brake sensor Lexus GS450h 2008 Do-it-yourself maintenance / LEXUS 2008 GS450H OWNER'S MANUAL (OM30A96U)

159
2-3. Operating the lights and windshield wipers
2
When driving
GS_HV_U
May 19, 2008 9:00 pm
AFS (Adaptive Front lighting System)
AFS improves visibility at intersectio ns and on curves by automatically
adjusting the level of the headlights according to vehicle speed and the
degree of the tire angle that are controlled by steering input.
Operates at speeds of 6 mph (10 km/h) or higher.
■ Deactivating AFS
Press the switch to turn it off.
The indicator turns on when
the AFS is deactivated.
■Daytime running light system
To make your vehicle more visible to other drivers, the headlights turn on automati-
cally (at a reduced intensity) whenever the hybrid system is started and the parking
brake is released. Daytime running lights are not designed for use at night.
■Headlight control sensor
The sensor may not function properly if an
object is placed on the sensor, or anything
that blocks the sensor is affixed to the wind-
shield. 
Doing so interferes with the sensor detecting
the level of ambient light and may cause the
automatic headlight system to malfunction.

172
2-4. Using other driving systems
GS_HV_U
January 4, 2008 10:02 am
Cruising in vehicle-to-vehicle distance control mode This mode employs a radar sensor to detect the presence of vehicles
within 400 ft. (120 m) ahead and to judge the distance between your
vehicle and those vehicles.
Note that vehicle-to-vehicle distance will close when trave ling on long down-
hill slopes.
Example of constant speed cruising 
When there are no vehicles ahead
The vehicle travels at the speed set by the driver. The desired vehicle-to-vehi-
cle distance can also be set by oper ating the vehicle-to-vehicle distance
switch.
Example of deceleration cruising 
When the vehicle ahead is driving slower than the set speed
When a vehicle is detected running ahead of you, in the same lane, the sys-
tem automatically decelerates your vehicle. When a greater reduction in
vehicle speed is necessary, the system applies the brakes. A warning tone
warns you when the system cannot decelerate sufficiently to prevent your
vehicle from closing on the vehicle ahead.

177
2-4. Using other driving systems
2
When driving
GS_HV_U
January 4, 2008 10:02 am
CAUTION
■Before using dynamic radar cruise control
Do not overly rely on vehicle-to-vehicle distance control.
Be aware of the set vehicle speed. If au tomatic deceleration/acceleration is not
appropriate, adjust the vehicle speed, as well as the distance between your vehicle
and vehicles ahead by applying the brakes, etc.
■To avoid operating the dynamic radar cruise control by mistake
Keep the “ON-OFF” button off when not in use.
■Situations unsuitable for dynamic radar cruise control
Do not use dynamic radar cruise contro l in any of the following situations.
Doing so may result in inappropriate cont rol of speed and could cause serious or
fatal accident.
●In heavy traffic
●On roads with sharp bends
●On winding roads
●On slippery roads, such as thos e covered with rain, ice or snow
●On steep downhills, where there are sudden changes between sharp up and
down gradients
Vehicle speed may exceed the set speed when driving down a steep hill.
●At entrances to expressways
●When weather conditions are bad enough that they may prevent the sensors
from functioning correctly (f og, snow, sandstorm, etc.)
●When the approach warning buzzer can be heard often

178
2-4. Using other driving systems
GS_HV_U
January 4, 2008 10:02 am
CAUTION
■When the radar sensor may not be correctly detecting the vehicle ahead
Apply the brakes as necessary when any of the following types of vehicles are in
front of you. 
As the sensor may not be able to correctly detect these types of vehicles, the prox-
imity alarm ( P. 509) will not be activated, and an accident may result.
●Vehicles that cut in suddenly
●Vehicles traveling at low speeds
●Vehicles that are not moving
●Vehicles with small rear ends (tra ilers with no load on board etc.)
●Motorcycles traveling in the same lane
■Conditions under which the vehicle-to-vehicle distance control may not function
correctly
Apply the brakes as necessary in the foll owing conditions as the radar sensor may
not be able to correctly detect vehicles ahead, and an accident may result.
●When water or snow thrown up by the surrounding vehicles hinders the function-
ing of the sensor
●When your vehicle is pointing upwards (caused by a heavy load in the trunk, etc.)
●When the road curves or when the lanes are narrow
●When steering wheel operation or your position in the lane is unstable
●When the vehicle ahead of you decelerates suddenly

191
2-4. Using other driving systems
2
When driving
GS_HV_U
January 4, 2008 10:02 am
■When using the intuitive parking assist
●The sensors’ detection areas and reaction times are limited. When moving for-
ward or reversing, check the areas surrounding the vehicle (especially the sides
of the vehicle) for safety, and drive slowly, using the brake to control the vehicle’s
speed.
• The sensors’ detection areas are limited to the areas around the vehicle’s front and rear bumpers.
• Depending on the shape of the obstacle and other factors, the detection dis-
tance may shorten, or dete ction may be impossible.
• There will be a short delay between ob stacle detection and display. Even at
slow speeds, there is a possibility that the obstacle will come within 0.8 ft. (25
cm) of the vehicle before the display is shown and the warning beep sounds.
• Braking distance may differ according to the road conditions (rain, gravel
etc.).
• It might be difficult to hear beeps due to the volume of audio system or air flow noise of air conditioning system.
• For long obstacles such as walls, the obstacle warning may change as the obstacle gets closer.

206
2-4. Using other driving systems
GS_HV_U
January 4, 2008 10:02 am
PCS (Pre-Collision System) (if equipped)
Radar sensorDetects vehicles or other obsta-
cles on or near the road ahead and
determines whether a collision is
imminent based on the position,
speed, and heading of the obsta-
cles. Grille cover
Radar sensor
Safety systems such as the brakes and seat belts are automatically
engaged to lessen impact and injuries to occupants as well as vehicle dam-
age when the radar sensor detects an unavoidable frontal collision.
■Pre-collision seat belts (front seats only)
The seat belts are immediately retracted as the effect of the pretensioner is
increased ( P. 67), to help prepare the driver and passengers. In the
event of sudden braking or skidding, the system will operate even if no
obstacle has been detected.
■ Pre-collision brake assist
Applies greater braking force in relation to how strongly the brake pedal is
depressed.
■ Pre-collision AVS
If the system determines that the collision is unavoidable, the operation of
AV S ( P. 199) helps prevent the vehicle front from going down when
hard brakes are applied.

207
2-4. Using other driving systems
2
When driving
GS_HV_U
January 4, 2008 10:02 am
■Obstacles not detected
The sensor cannot detect plastic obstacles such as pylons. There may also be occa-
sions when the radar sensor cannot detect pedestrians, animals, bicycles, motorcy-
cles, trees, or snowdrifts.
■The pre-collision system is operational when
●Seat belts (linked to the radar sensor)
• Vehicle speed is above 3 mph (5 km/h).
• The speed at which your vehicle is approaching the obstacle or oncoming vehicle exceeds 18 mph (30 km/h).
• The front occupants are wearing a seat belt.
●Seat belts (linked to brake operation)
• Vehicle speed exceeds 18 mph (30 km/h).
• The system detects sudd en braking or skidding.
• The front occupants are wearing a seat belt.
●Brake assist
• Vehicle speed is above 18 mph (30 km/h).
• The speed at which your vehicle is approaching the obstacle or oncoming vehicle exceeds 18 mph (30 km/h).
• The brake pedal is depressed.
●AV S
• Vehicle speed is above 3 mph (5 km/h).
• The speed at which your vehicle is approaching the obstacle or oncoming vehicle exceeds 18 mph (30 km/h).

465
4-3. Do-it-yourself maintenance
4
Maintenance and care
GS_HV_U
December 27, 2007 1:38 pm
FuseAmpereCircuit
10ECU-IG LH10
VGRS, EPS, electronically con-
trolled brake system, yaw rate & G
sensor, dynamic radar cruise control
system, rear view monitor system,
moon roof
11PA N E L7. 5
Steering switches, distance control
switch, audio system, glove box light,
switch illumination, cigarette lighter,
shift lever light, touch screen, rear
personal lights
12S/ROOF25Moon roof
13FUEL OPEN10Fuel lid opener
14LH-B10Theft deterrent system
15TRK OPN10Trunk opener
16TV7. 5Touch screen, rear view monitor sys-
tem
17A/C7. 5Air conditioning system
18FR P/SEAT LH30Po w e r s e a t

5
When trouble arises
489
5-1. Essential information
GS_HV_U
December 12, 2007 3:50 pm
Event data recorder
In a crash or a near car crash eventThe SRS airbag sensor ass embly contains the EDR. In a crash or a near
car crash event, this devic e may record some or all of the following infor-
mation:
● Gasoline engine speed
● Whether the brake pedal was applied or not
● Vehicle speed
● To what extent the accelerator pedal was depressed
● Position of the transmission shift lever
● Whether the driver and front passenger wore seat belts or not
● Driver’s seat position
● SRS airbag deployment data
● SRS airbag system diagnostic data
● Front passenger’s occupant classification
Your vehicle has computers that monitor and control certain aspects of
your vehicle. These computers assist in driving and maintaining optimal
vehicle performance.
Besides storing data useful for troublesh ooting, there is a system to record
data in a crash or a near car crash event. This is called an Event Data
Recorder (EDR).

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5-2. Steps to take in an emergency
GS_HV_U
December 12, 2007 3:50 pm
Have the vehicle inspected immediately.Failing to investigate the cause of th e following warning may lead to the
system operating abnormally and possibly cause an accident. Have the
vehicle inspected by your Lexus dealer immediately.
*: Electronically Controlled Brake System
Wa r n i n g m e s s a g eDetails
Malfunction in the TRAC, VSC or hill-start assist con-
trol system.
“CHECK ECB
*” may be displayed at the same time,
or on its own.
(U.S.A.)
(Canada)
Malfunction in the ABS or brake assist system. “CHECK ECB*” may be displayed at the same time,
or on its own.
Malfunction in the VGRS.
(If equipped, steering guide symbol and
arrows are flashing)
The steering sensor cable is broken and signals can-
not be received.