brake LEXUS RX400H 2008 Service Manual

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4-3. Do-it-yourself maintenance
RX400h_U
■Brake fluid can absorb moisture from the air
Excess moisture in the fluid can cause a dangerous loss of braking efficiency. Use
only newly opened brake fluid.
CAUTION
■When filling the reservoir
Take care because brake fluid can harm your hands or eyes and damage painted
surfaces.
If fluid gets in your eyes, flush your eyes with clean water immediately.
If you still experience discomfort, see a doctor.
NOTICE
■If the fluid level is low or high
It is normal for the brake fluid level to go down slightly as the brake pads wear or
when the fluid level in the accumulator is high.
If the reservoir needs frequent refilling, it may indicate a serious problem.

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4-3. Do-it-yourself maintenance
4
Maintenance and care
RX400h_U
Fuse layout and amperage ratings■ Engine compartment (type A)
FuseAmpereCircuit
1ABS MTR230Electronically controlled brake system
2ETCS10Hybrid system
3DC/DC-S10Hybrid system
4ABS NO.210Electronically controlled brake system
5ABS NO.110Electronically controlled brake system
6BATT FAN15Hybrid system
7ABS NO.315Electronically controlled brake system
8OIL PUMP10Transaxle fluid cooling system
9ABS MTR130Electronically controlled brake system
10ST7. 5Hybrid system

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RX400h_U
5-1. Essential information
If your vehicle needs to be towed
Before towingThe following may indicate a problem with your transmission. Contact
your Lexus dealer before towing.
● The hybrid system is running, but the vehicle will not move.
● The vehicle makes an abnormal sound.
Emergency towing
If a tow truck is not available, in an emergency your vehicle may be tem-
porarily towed using a cable or chain secured to the emergency towing
eyelet(s). This should only attempted on hard, surfaced roads for short
distances at low speeds.
A driver must be in the vehicle to steer and operate the brakes. The vehi-
cle’s wheels, drive train, axles, steer ing and brakes must be in good condi-
tion.
Towing eyelets
If towing is necessary, we recommend having your vehicle towed by your
Lexus dealer or a commercial towing se rvice, using a lift-type truck or a flat
bed truck.
Use a safety chain system for all towing, and abide by all state/provincial
and local laws.
If towing from the front, the vehicle’s rear wheels and axles must be in good
condition. ( →P. 3 8 2 )
If they are damaged, use a towing dolly or flat bed truck.

5
When trouble arises
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5-1. Essential information
RX400h_U
■Emergency towing procedureRelease the parking brake.
Shift the shift lever to N.
Turn the engine switch to the ACC (hybrid system off) or ON (hybrid sys-
tem on) position.
CAUTION
■Caution while towing
●Use extreme caution when towing the vehicle.
Avoid sudden starts or erratic driving maneuvers which place excessive stress on
the emergency towing eyelets and the cables or chains.
●If the hybrid system is not running, the power assist for the brakes and steering
will not function, making steering and braking more difficult.
NOTICE
■To prevent causing serious damage to the transmission
Never tow this vehicle from the rear with four wheels on the ground.
This may cause serious damage to the transmission.
STEP1
STEP2
STEP3

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5-1. Essential information
RX400h_U
Towing with a wheel lift-type truckFrom the front (2WD models) Release the parking brake.
From the front (AWD models) Use a towing dolly under the rear
wheel.
NOTICE
■To prevent damaging the vehicle
When raising the vehicle, ensure adequate ground clearance for towing at the
opposite end of the raised vehicle.
Without adequate clearance, the vehicle could be damaged while being towed.
■To prevent causing serious damage to the transmission (AWD models)
Never tow this vehicle from the front with the rear wheels on the ground.

5
When trouble arises
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5-1. Essential information
RX400h_U
If you think something is wrong
If you notice any of the following symptoms, your vehicle probably needs
adjustment or repair. Contact your Lexus dealer as soon as possible.
■Visible symptoms
●Fluid leaks under the vehicle
(Water dripping from the air conditioning after use is normal.)
● Flat-looking tires or uneven tire wear
● Engine coolant temperature gauge needle continually points
higher than normal
■ Audible symptoms
●Changes in exhaust sound
● Excessive tire squeal when cornering
● Strange noises related to the suspension system
● Pinging or other noises related to the hybrid system
■ Operational symptoms
●Engine missing, stumbling or running rough
● Appreciable loss of power
● Vehicle pulls heavily to one side when braking
● Vehicle pulls heavily to one side when driving on a level road
● Loss of brake effectiveness, sp ongy feeling, pedal almost touches
the floor

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5-1. Essential information
RX400h_U
Event data recorder
In a crash or a near car crash eventThe SRS airbag sensor assembly contains the EDR. In a crash or a near
car crash event, this device may record some or all of the following infor-
mation:
● Gasoline engine speed
● Whether the brake pedal was applied or not
● Ve h i c l e s p e e d
● 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
The information above is intended to be used for the purpose of improv-
ing vehicle safety performance. Unlike general data recorders, the EDR
does not record sound data such as conversation between passengers.
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 troubleshooting, there is an event data
recorder (EDR) that records data in a crash or a near car crash event.

388
RX400h_U
5-2. Steps to take in an emergency
If a warning light turns on or a warning buzzer sounds...
Stop the vehicle immediately. Continuing to drive the vehicle may be dangerous.
The following warning indicates a possible problem in the brake system.
Immediately stop the vehicle in a safe place and contact your Lexus
dealer.
*: Parking brake engaged warning buzzer:
→P. 4 0 2
Warning lightWarning light/Details
(U.S.A.)

(Canada)
Brake system warning light (warning buzzer)*
•Low brake fluid
• Malfunction in the electronically controlled brake system
This light also comes on when the parking brake is not
released. If the light turns off after the parking brake is fully
released the system is operating normally.
(U.S.A.)

(Canada)Brake system warning lightIndicates a malfunction in the vehicle’s brake system.
Calmly perform the following actions if any of the warning lights turn on or
flash. If a light turns on or flashes, but then turns off, this does not necessar-
ily indicate a malfunction in the system.

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5-2. Steps to take in an emergency
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Warning lightWarning light/Details
(U.S.A.)

(Canada)
ABS warning lightIndicates a malfunction in:
•The ABS;
• The brake assist system.
Brake system warning lightIndicates a malfunction in:
• Electronically controlled brake system; or
• Regenerative brake system.
Electric power steering warning lightMalfunction in the EPS.

5
When trouble arises
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5-2. Steps to take in an emergency
RX400h_U
CAUTION
■If the tire pressure warning light comes on
Be sure to observe the following precautions. Failure to do so could cause loss of
vehicle control and result in death or serious injury.
●Stop your vehicle in a safe place as soon as possible. Adjust the tire inflation pres-
sure immediately.
●If the tire pressure warning light comes on even after tire inflation pressure adjust-
ment, it is probable that you have a flat tire. Check the tires. If the tire is flat,
change to the spare tire and have the flat tire repaired by the nearest Lexus
dealer.
●Avoid abrupt maneuvering and braking. If the vehicle tires deteriorate, you could
lose control of the steering wheel or the brakes.
■If a blowout or sudden air leakage should occur
The tire pressure warning system may not activate immediately.