Page 6 of 632
IMPORTANT INFORMATION ABOUT YOUR LEXUS
vi
Leak detection pump
This pump performs fuel evaporation leakage check. This
check is done several hours after the engine is turned off. So
you may hear sound coming from underneath the luggage
compartment for several minutes. It does not indicate a
malfunction.
Page 543 of 632

SECTION 6 – 2
519
SERVICE PROCEDURES AND
SPECIFICATIONS
Engine
Specifications (GS430)520
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifications (GS300) 523
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel 526
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . \
. . . . . . . . . . . . . . . .
Fuel pump shut off system 528
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Facts about engine oil consumption 528
. . . . . . . . . . . . . . . . . . . . . . . .
Used engine oil 530
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . .
Checking the engine oil level 530
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Checking the engine coolant level 534
. . . . . . . . . . . . . . . . . . . . . . . . . .
Checking the radiator and condenser 536
. . . . . . . . . . . . . . . . . . . . . . .
Spark plugs 537
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . .
Page 550 of 632

ENGINE
526
FUEL
Fuel type
Your vehicle must use only unleaded gasoline.
To help prevent gas station mixups, your Lexus has a smaller
fuel tank opening. The special nozzle on pumps with unleaded
fuel will fit it, but the larger standard nozzle on pumps with
leaded gas will not.
At a minimum, the gasoline you use should meet the
specifications of ASTM D4814 in the U.S.A. and CGSB
3.5−M93 in Canada.
NOTICE
Do not use leaded gasoline. Use of leaded gasoline will
cause the three way catalytic converter to lose its
effectiveness and the emission control system to
function improperly. Also, this can increase
maintenance costs.
Octane rating
Premium unleaded gasoline with an Octane Rating of 91
(Research Octane Number 96) or higher required for
optimum engine performance. However, if such premium
type cannot be obtained, you may use unleaded gasoline
with an Octane Rating as low as 87 (Research Octane
Number 91). Use of unleaded fuel with an octane number or rating lower
than stated above will cause persistent heavy knocking. If
severe, this will lead to engine damage.
If your engine knocks ...
If you detect heavy knocking even when using the
recommended fuel, or if you hear steady knocking while
holding a steady speed on level roads, consult your Lexus
dealer.
However, occasionally, you may notice light knocking for a
short
time while accelerating or driving up hills. This is normal
and there is no need for concern.
Gasoline containing detergent additives
Lexus recommends the use of gasoline that contains
detergent a dditives to avoid build up of engine deposits.
However, all gasoline sold in the U.S. contains detergent
additives to keep clean and/or clean intake systems.
Quality gasoline
Automotive manufacturers in the U.S., Europe and Japan
have developed a specificat ion for quality fuel named
World Wide Fuel Charter (WWFC) that is expected to be
applied world wide. The WWFC consists of four
categories that depend on required emission levels. In the
U.S., category 3 has been adopted. The WWFC improves
air quality by providing for better emissions in vehicle
fleets, and customer satisfaction through better vehicle
performance.
Page 552 of 632

ENGINE
528
FUEL PUMP SHUT OFF SYSTEM
The fuel pump shut off system stops supplying fuel to the
engine to minimize the risk of fuel leakage when the engine
stalls or an airbag inflates upon collision. To restart the engine
after the fuel pump shut off system activates, turn the engine
switch off once and start it.
CAUTION
Inspect the ground under the vehicle before restarting
the engine. If you find that liquid has leaked onto the
ground, it is the fuel system that has been damaged and
it is in need of repair. In this case, do not restart the
engine.
FACTS ABOUT ENGINE OILCONSUMPTION
Functions of engine oil
Engine oil has the primary function of lubricating and cooling
the inside of the engine, and plays a major role in maintaining
the engine in proper working order.
Engine oil consumption
It is normal that an engine should consume some engine
oil during normal engine operation. The causes of oil
consumption in a normal engine are as follows.
Oil is used to lubricate pistons, piston rings and cylinders.
A thin film of oil is left on the cylinder wall when a piston
moves downwards in the cylinder. High negative pressure
generated when the vehicle is decelerating sucks some of
this oil into the combustion chamber. This oil as well as
some part of the oil film left on the cylinder wall is burned by
the high temperature combustion gases during the
combustion process.
Oil is also used to lubricate the stems of the intake valves.
Some of this oil is sucked into the combustion chamber
together with the intake air and is burned along with the fuel.
High temperature exhaust gases also burn the oil used to
lubricate the exhaust valve stems.
Page 573 of 632

CHASSIS
549
Inspection and adjustment procedure
G63001
1Tire valve
2Tire pressure gauge
1. Remove the tire valve cap.
2. Press the tip of the tire pressure gauge to the tire
valve.
3. Read the pressure using the graduations of the
gauge.
4. In case the tire inflation pressure is not within the
prescribed range, insert the compressed air from the
valve. In case of applying too much air, press the center
of the valve and release the air to adjust.
5. After completing the tire inflation pressure
measurement and adjustment, apply soapy water to the
valve and check for leakage. 6. Install the tire valve cap.
If a gauge and air pump are not available, have your
vehicle checked by your Lexus dealer.
CAUTION
Be sure to reinstall the tire valve caps. W
ithout the
valve caps, dirt or moisture could get into the
valve core and cause air leakage. If the caps have
been lost, have new ones put on as soon as
possible.
Incorrect tire inflation pressure may waste fuel, reduce
the comfort of driving, reduce tire life and make your
vehicle less safe to drive.
If a tire needs frequent refilling, have it checked by your
Lexus dealer.
Page 604 of 632

ELECTRICAL COMPONENTS
580
No.FUSEAMPERECIRCUIT
70 A/F15Multi−port fuel injection
system/sequential multiport fuel
injection system
71 ETCS10Multi−port fuel injection
system/sequential multiport fuel
injection system
72 ALT S7.5Charging system
73 EM VLV10No circuit
74 H LP CLN30Headlight cleaner system
75 A/C COMP7.5Air conditioning system
76 DEICER25No circuit
77 FR
CTRL AM30“FR TAIL”, “FR FOG” and
“WASHER”
78 IG210Starting system
79 EFI NO.210
Multi− port fuel injection
system/sequential multiport fuel
injection system, Evaporative
system
80 H LP R
LW R15Right− hand headlight (low
beam)
81 H LP L
LW R15Left− hand headlight (low beam)
82 F/PMP25Fuel pump
No.FUSEAMPERECIRCUIT
83 EFI
GS430:
20
GS300: 25Multi− port fuel injection
system/sequential multiport fuel
injection system
84 INJ20Multi− port fuel injection
system/sequential multiport fuel
injection system
85 H LP UPR15Headlights (high beam)
86 HORN10Horn
87 WASHER20Windshield wipers and washer
88 FR TAIL10Parking lights, Side marker
lights
89 FR FOG15Front fog lights
90 RR
S/SHADE7.5Rear electric sunshade
91 PSB30Pre− collision system
92 RR IG210No circuit
93 RR IG110Pre− collision system, Rear
electric sunshade, Seat belt
pretensioners
94 RR B10Luggage compartment light,
Noise filter
95 RR FOG7.5Rear fog lights
96 STOP LP L10Stoplights, Back up lights