2000 LEXUS GS400 service

IN04S±10
IN±20± INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
20 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS
GENERAL INFORMATION
A large number of ECU controlled systems are used in the LEXUS GS400/GS300. In general, the ECU con-
trolled system is considered to be a very intricate system requiring a high level of technical knowledge and
expert skill to troubleshoot. However, the fact is that if you proceed to inspect the circuits one by one, trouble-
shooting of these systems is not complex. If you have adequate understanding of the system and a basic
knowledge of electricity, accurate diagnosis and necessary repair can be performed to locate and fix the
problem. This manual is designed through emphasis of the above standpoint to help service technicians
perform accurate and effective troubleshooting, and is compiled for the following major ECU controlled sys-
tems:
The troubleshooting procedure and how to make use of it are described on the following pages.
SystemPage
1. Engine 2JZ ± GEDI±1
2. Engine 1UZ ± FEDI±156
3. Automatic TransmissionDI±316
4. ABS & Hydraulic Brake Booster Power Supply SystemDI±387
5. Vehicle Skid Control (VSC) & Brake Assist (BA) SystemDI±473
6. Power Tilt and Power Telescopic Steering ColumnDI±517
7. Supplemental Restraint SystemDI±550
8. Power Seat Control SystemDI±683
9. Cruise Control SystemDI±704
10.Engine Immobiliser SystemDI±726
11. Combination Meter SystemDI±744
12.Sliding Roof SystemDI±764
13.Body No. 1 Control SystemDI±776
14.Body No. 2 Control SystemDI±820
15.Driver Door Control SystemDI±856
16.Passenger Door Control SystemDI±889
17.Rear Left Door Control SystemDI±921
18.Rear Right Door Control SystemDI±938
19.Multiplex Communication SystemDI±955
20.LEXUS Navigation SystemDI±1022
21.Air Conditioning SystemDI±1059
FOR USING OBDII SCAN TOOL OR LEXUS HAND±HELD TESTER

Before using the scan tool or tester, the scan tool's instruction book or tester's operator manual should
be read thoroughly.

If the scan tool or tester cannot communicate with ECU controlled systems when you have connected
the cable of the scan tool or tester to DLC3, turned the ignition switch ON and operated the scan tool,
there is a problem on the vehicle side or tool side.
(1) If communication is normal when the tool is connected to another vehicle, inspect the diagnosis
data link line (Bus
line) or ECU power circuit of the vehicle.
(2) If communication is still not possible when the tool is connected to another vehicle, the problem
is probably in the tool itself, so perform the Self Test procedures outline in the Tester Operator's
Manual.

± INTRODUCTIONTERMS
IN±39
39 Author: Date:
2000 LEXUS GS300/GS400 (RM718U) OEM
Original Equipment Manufacturing
OHCOverhead Camshaft
OHVOverhead Valve
OPTOption
O/SOversize
P & BVProportioning And Bypass Valve
PCSPower Control System
PCVPositive Crankcase Ventilation
PKBParking Brake
PPSProgressive Power Steering
PSPower Steering
PTOPower Take±Off
R & PRack And Pinion
R/BRelay Block
RBSRecirculating Ball Type Steering
R/FReinforcement
RFSRigid Front Suspension
RHRight±Hand
RHDRight±Hand Drive
RLYRelay
ROMRead Only Memory
RrRear
RRRear±Engine Rear±Wheel Drive
RRSRigid Rear Suspension
RWDRear±Wheel Drive
SDNSedan
SENSensor
SICSStarting Injection Control System
SOCState Of Charge
SOHCSingle Overhead Camshaft
SPECSpecification
SPISingle Point Injection
SRSSupplemental Restraint System
SSMSpecial Service Materials
SSTSpecial Service Tools
STDStandard
STJCold±Start Fuel Injection
SWSwitch
SYSSystem
T/ATransaxle
TACHTachometer
TBIThrottle Body Electronic Fuel Injection
TCTurbocharger
TCCSTOYOTA Computer±Controlled System
TCVTiming Control Valve
TDCTop Dead Center

BE1367
Medium Current Fuse and High Current Fuse
Equal Amperage Rating
V00076
Abbreviation Part Name Symbol Illustration
FUSE
MEDIUM CURRENT FUSE
HIGH CURRENT FUSE
FUSIBLE LINK
CIRCUIT BREAKERFUSE
M±FUSE
H±FUSE
FL
CB
± INTRODUCTIONREPAIR INSTRUCTIONS
IN±5
5 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(3) Precoated parts are indicated in the component il-
lustrations by the º
º symbol.
(g) When necessary, use a sealer on gaskets to prevent
leaks.
(h) Carefully observe all specifications for bolt tightening
torques. Always use a torque wrench.
(i) Use of special service tools (SST) and special service ma-
terials (SSM) may be required, depending on the nature
of the repair. Be sure to use SST and SSM where speci-
fied and follow the proper work procedure. A list of SST
and SSM can be found in Preparation section in this
manual.
(j) When replacing fuses, be sure the new fuse has the cor-
rect amperage rating. DO NOT exceed the rating or use
one with a lower rating.

IN±42
± INTRODUCTIONTERMS
42 Author: Date:
2000 LEXUS GS300/GS400 (RM718U) HO2S
Heated Oxygen SensorHeated Oxygen Sensor (HO2S)
IACIdle Air ControlIdle Speed Control (ISC)
IATIntake Air TemperatureIntake or Inlet Air Temperature
ICMIgnition Control Module±
IFIIndirect Fuel InjectionIndirect Injection (IDL)
IFSInertia Fuel±Shutoff±
ISCIdle Speed Control±
KSKnock SensorKnock Sensor
MAFMass Air FlowAir Flow Meter
MAPManifold Absolute PressureManifold Pressure
Intake Vacuum
MCMixture Control
Electric Bleed Air Control Valve (EBCV)
Mixture Control Valve (MCV)
Electric Air Control Valve (EACV)
MDPManifold Differential Pressure±
MFIMultiport Fuel InjectionElectronic Fuel Injection (EFI)
MILMalfunction Indicator LampCheck Engine Lamp
MSTManifold Surface Temperature±
MVZManifold Vacuum Zone±
NVRAMNon±Volatile Random Access Memory±
O2SOxygen SensorOxygen Sensor, O2 Sensor (O2S)
OBDOn±Board DiagnosticOn±Board Diagnostic System (OBD)
OCOxidation Catalytic ConverterOxidation Catalyst Convert (OC), CCo
OPOpen LoopOpen Loop
PAIRPulsed Secondary Air InjectionAir Suction (AS)
PCMPowertrain Control Module±
PNPPark/Neutral Position±
PROMProgrammable Read Only Memory±
PSPPower Steering Pressure±
PTOXPeriodic Trap OxidizerDiesel Particulate Filter (DPF)
Diesel Particulate Trap (DPT)
RAMRandom Access MemoryRandom Access Memory (RAM)
RMRelay Module±
ROMRead Only MemoryRead Only Memory (ROM)
RPMEngine SpeedEngine Speed
SCSuperchargerSupercharger
SCBSupercharger BypassE±ABV
SFISequential Multiport Fuel InjectionElectronic Fuel Injection (EFI), Sequential Injection
SPLSmoke Puff Limiter±
SRIService Reminder Indicator±
SRTSystem Readiness Test±
STScan Tool±
TBThrottle BodyThrottle Body
TBIThrottle Body Fuel InjectionSingle Point Injection
Central Fuel Injection (Ci)
TCTurbochargerTurbocharger
TCCTorque Converter ClutchTorque Converter

MA001±07
± MAINTENANCEOUTSIDE VEHICLE
MA±1
44 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
OUTSIDE VEHICLE
GENERAL MAINTENANCE
These are maintenance and inspection items which are considered to be the owner's responsibility.
They can be done by the owner or they can have them done at a service shop.
These items include those which should be checked on a daily basis, those which, in most cases, do not
require (special) tools and those which are considered to be reasonable for the owner to do.
Items and procedures for general maintenance are as follows.
1. GENERAL NOTES

Maintenance items may vary from country to country. Check the owner's manual supplement in which
the maintenance schedule is shown.

Every service item in the periodic maintenance schedule must be performed.

Periodic maintenance service must be performed according to whichever interval in the periodic main-
tenance schedule occurs first, the odometer reading (miles) or the time interval (months).

Maintenance service after the last period should be performed at the same interval as before unless
otherwise noted.

Failure to do even one item an cause the engine to run poorly and increase exhaust emissions.
2. TIRES
(a) Check the pressure with a gauge. If necessary, adjust.
(b) Check for cuts, damage or excessive wear.
3. WHEEL NUTS
When checking the tires, check the nuts for looseness or for missing nuts. If necessary, tighten them.
4. TIRE ROTATION
Check the owner's manual supplement in which the maintenance schedule is shown.
5. WINDSHIELD WIPER BLADES
Check for wear or cracks whenever they do not wipe clean. If necessary, replace.
6. FLUID LEAKS
(a) Check underneath for leaking fuel, oil, water or other fluid.
(b) If you smell gasoline fumes or notice any leak, have the cause found and corrected.
7. DOORS AND ENGINE HOOD
(a) Check that all doors and the tailgate operate smoothly, and that all latches lock securely.
(b) Check that the engine hood secondary latch secures the hood from opening when the primary latch
is released.

MA002±06
MA±2
± MAINTENANCEINSIDE VEHICLE
45 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
INSIDE VEHICLE
GENERAL MAINTENANCE
These are maintenance and inspection items which are considered to be the owner's responsibility.
They can be done by the owner or they can have them done at a service shop.
These items include those which should be checked on a daily basis, those which, in most cases, do not
require (special) tools and those which are considered to be reasonable for the owner to do.
Items and procedures for general maintenance are as follows.
1. GENERAL NOTES

Maintenance items may vary from country to country. Check the owner's manual supplement in which
the maintenance schedule is shown.

Every service item in the periodic maintenance schedule must be performed.

Periodic maintenance service must be performed according to whichever interval in the periodic main-
tenance schedule occurs first, the odometer reading (miles) or the time interval (months).

Maintenance service after the last period should be performed at the same interval as before unless
otherwise noted.

Failure to do even one item an cause the engine to run poorly and increase exhaust emissions.
2. LIGHTS
(a) Check that the headlights, stop lights, taillights, turn signal lights, and other lights are all working.
(b) Check the headlight aiming.
3. WARNING LIGHTS AND BUZZERS
Check that all warning lights and buzzers function properly.
4. HORN
Check that it is working.
5. WINDSHIELD GLASS
Check for scratches, pits or abrasions.
6. WINDSHIELD WIPER AND WASHER
(a) Check operation of the wipers and washer.
(b) Check that the wipers do not streak.
7. WINDSHIELD DEFROSTER
Check that air comes out from the defroster outlet when operating the heater or air conditioner.
8. REAR VIEW MIRROR
Check that it is mounted securely.
9. SUN VISORS
Check that they move freely and are mounted securely.
10. STEERING WHEEL
Check that it has the specified freeplay. Be alert for changes in steering condition, such as hard steering,
excessive freeplay or strange noises.
11. SEATS
(a) Check that all front seat controls such as seat adjusters, seatback recliner, etc. operate smoothly.
(b) Check that all latches lock securely in any position.
(c) Check that the locks hold securely in any latched position.
(d) Check that the head restraints move up and down smoothly and that the locks hold securely in any
latches position.
(e) For folding±down rear seat backs, check that the latches lock securely.
12. SEAT BELTS
(a) Check that the seat belt system such as the buckles, retractors and anchors operate properly and
smoothly.
(b) Check that the belt webbing is not cut, frayed, worn or dameged.

MA003±06
MA±4
± MAINTENANCEUNDER HOOD
47 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
UNDER HOOD
GENERAL MAINTENANCE
1. GENERAL NOTES

Maintenance items may vary from country to country. Check the owner's manual supplement in which
the maintenance schedule is shown.

Every service item in the periodic maintenance schedule must be performed.

Periodic maintenance service must be performed according to whichever interval in the periodic main-
tenance schedule occurs first, the odometer reading (miles) or the time interval (months).

Maintenance service after the last period should be performed at the same interval as before unless
otherwise noted.

Failure to do even one item an cause the engine to run poorly and increase exhaust emissions.
2. WINDSHIELD WASHER FLUID
Check that there is sufficient fluid in the tank.
3. ENGINE COOLANT LEVEL
Check that the coolant level is between the ºFULLº and ºLOWº lines on the see±through reservoir.
4. RADIATOR AND HOSES
(a) Check that the front of the radiator is clean and not blocked with leaves, dirt or bugs.
(b) Check the hoses for cracks, kinks, rot or loose connections.
5. BATTERY ELECTROLYTE LEVEL
Check that the electrolyte level of all battery cells is between the upper and lower level lines on the case.
6. BRAKE FLUID LEVEL
Check that the brake fluid levels are near the upper level line on the see±through reservoirs.
7. ENGINE DRIVE BELT
Check drive belt for fraying, cracks, wear or oiliness.
8. ENGINE OIL LEVEL
Check the level on the dipstick with the engine turned off.
9. POWER STEERING FLUID LEVEL

Check the level on the dipstick.

The level should be in the ºHOTº or ºCOLDºrange depending on the fluid temperature.
10. AUTOMATIC TRANSMISSION FLUID LEVEL
(a) Park the vehicle on a level surface.
(b) With the engine idling and the parking brake applied, shift the selector into all positions from ºPº to ºLº,
and then shift into ºPº position.
(c) Pull out the dipstick and wipe off the fluid with a clean rag. Re±insert the dipstick and check that the
fluid level is in the HOT range.
(d) Do this check with the fluid at normal driving temperature (70 ± 80°C, 158 ± 176°F).
HINT:
Wait until the engine cools down (approx. 30 min.) before checking the fluid level after extended driving at
high speeds, in hot weather, in heavy traffic or pulling a trailer.
11. EXHAUST SYSTEM
If any change in the sound of the exhaust or smell of the exhaust fumes is noticed, have the cause located
and corrected.

PP0SN±01
PP±100
± PREPARATIONAIR CONDITIONING
152 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
AIR CONDITIONING
SST (Special Service Tools)
07110±58060Air Conditioner Service Tool Set
(07117±58060)Refrigerant Drain Service Valve
(07117±58070)T±Joint
(07117±58080)Quick Disconnect AdapterHigh pressure side
(07117±58090)Quick Disconnect AdapterLow pressure side
(07117±88060)Refrigerant Charging HoseHigh pressure side
(Color: Red)
(07117±88070)Refrigerant Charging HoseLow pressure side
(Color: Blue)
(07117±88080)Refrigerant Charging HoseUtility
(Color: Green)
07110±61050Wrench SetExpansion valve
(07111±21020)Holder
(07111±32020)Hexagon Wrench5 mm (0.20 in.)
07112±66040Magnetic Clutch Remover