2000 LEXUS GS400 air condition

6RadioPOOR RECEPTION
Is the condition bad in comparison with other vehicles?
Are there any additional installation parts?
(Sun shade film, telephone antenna, etc.)
Check if there is any scratch and breaking of a wire on
the glass antenna and the defogger pattern.
(visual check. tester)
(See page
BE±190)
Is the contact of the plug jack of the radio OK?
Does the condition get better by using the outer
antenna (such as pillar antenna)?
Is the contact of the antenna terminal on the glass
surface and the defogger terminal?
Is the continuity of the antenna cord OK?
Check the grounding of the antenna, antenna cord,
choke coil, and noise filter. (See page BE±190)
Does the condition get better by replacing
the choke coil?
Does the condition get better by replacing the
antenna cord?Take a measure for contact. An electric wave environment is bad.
Does the condition get better if
removing them?
Influence of additional installation parts.
Repair. (See page BE±108)
Check the radio.
Take a measure for contact.
Grounding failure. Replace the antenna cord.
Replace the choke coil.
Replace the antenna cord. Ye s
No
Exchange the glass.Ye s
Ye s
Ye s
Ye s
Ye s
Ye s
Ye s
Ye s No
No
No
NoNo
No
No
No
NG
OK
Ye s BE±202
± BODY ELECTRICALAUDIO SYSTEM
2503 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)

I04189
Wire Harness Side
Connector ºBº
Connector ºDº Connector ºCº Connector ºAº
± BODY ELECTRICALAUDIO SYSTEM
BE±221
2522 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
6. NAKAMICHI made:
INSPECT RADIO RECEIVER ASSEMBLY CIRCUIT
Disconnect the connectors from the radio receiver assembly,
and inspect the connector on the wire harness side.
Tester connectionConditionSpecified condition
D3 ± GroundConstantContinuity
D4 ± GroundConstantBattery positive voltage
D1 ± GroundIgnition switch LOCKNo voltage
D1 ± GroundIgnition switch ACC or ONBattery positive voltage
*: w/ LEXUS navigation system
If the circuit is not as specified, inspect the circuits connected
to other parts.
HINT:
Check the wire harness between radio receiver assembly and
the CD auto changer, between radio receiver assembly and
power amplifier.
7. INSPECT GLASS IMPRINTED ANTENNA
(Use same procedure as for ºINSPECT DEFOGGER WIRESº
on page BE±108.)
8. REPAIR GLASS IMPRINTED ANTENNA
(Use same procedure as for ºREPAIR DEFOGGER WIRESº on
page BE±108.)

B06547
Fuel Tank Cap
B06840
AirDisconnect
EVAP Line Hose
B06841Air
Disconnect
Plug
Disconnect
EVAP Line Hose
Purge Line
Hose
Purge Port
± EMISSION CONTROL (2JZ±GE)EVAPORATIVE EMISSION (EVAP) CONTROL SYSTEM
EC±9
1460 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(3) Check if the pressure decreases when the fuel tank
cap is removed while adding pressure.
HINT:
If the pressure does not decrease when the filler cap is re-
moved, then you can conclude that the hose connecting the
service port to the fuel tank is blocked, etc.
(k) Disconnect the pressure gauge from the EVAP service
port on the purge line.
5. CHECK AIRTIGHTNESS IN FUEL TANK AND FILLER
PIPE
(a) Disconnect the EVAP line hose from the charcoal canister
side and then pressurize and make the internal pressure
in the fuel tank 4 kPa (41 gf/cm
2, 0.58 psi).
(b) Check that the internal pressure of the fuel tank can be
hold for 1 minute.
(c) Check the connected portions of each hose and pipe.
(d) Check the installed parts on the fuel tank.
If there is no abnormality, replace the fuel tank and filler pipe.
(e) Reconnect the EVAP line hose to the charcoal canister.
6. INSPECT FUEL CUTOFF VALVE AND FILL CHECK
VA LV E
(a) Disconnect the purge line hose and EVAP line hose from
the charcoal canister.
(b) Disconnect the air drain hose from the canister tank, and
plug its.
(c) Pressurize 4 kPa (41 gf/cm
2, 0.58 psi) to the purge port
and check that there is ventilation through the EVAP line
hose.
HINT:
In the condition that the fuel fuel is full, as the float value of the
fill check valve is closed and has no ventilation, it is necessary
to check the fuel amount (volume).
(d) Check if there is any struck in the vent line hose and EVAP
line hose.
If there is no stuck in hoses, replace the fuel cutoff valve and fill
check valve.
(e) Reconnect the purge line hose and EVAP line hose to the
charcoal canister.
(f) Reconnect the air drain hose to the canister tank.

EM0D0±01
A00982
CO/HC Meter
± ENGINE MECHANICAL (2JZ±GE)CO/HC
EM±1
1355 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
CO/HC
INSPECTION
HINT:
This check is used only to determine whether or not the idle
CO/HC complies with regulations.
1. INITIAL CONDITIONS
(a) Engine at normal operating temperature
(b) Air cleaner installed
(c) All pipes and hoses of air induction system connected
(d) All accessories switched OFF
(e) All vacuum lines properly connected
(f) SFI system wiring connectors fully plugged
(g) Ignition timing checked correctly
(h) Transmission in neutral position
(i) Tachometer and CO/HC meter calibrated by hand
2. START ENGINE
3. RACE ENGINE AT 2,500 RPM FOR APPROX. 180
SECONDS
4. INSERT CO/HC METER TESTING PROBE AT LEAST
40 cm (1.3 ft) INTO TAILPIPE DURING IDLING
5. IMMEDIATELY CHECK CO/HC CONCENTRATION AT
IDLE AND/OR 2,500 RPM
HINT:
When doing the 2 mode (2,500 rpm and idle) test, follow the
measurement order prescribed by the applicable local regula-
tions.

EM0D4±01
± ENGINE MECHANICAL (2JZ±GE)IDLE SPEED
EM±13
1367 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
IDLE SPEED
INSPECTION
1. INITIAL CONDITIONS
(a) Engine at normal operating temperature
(b) Air cleaner installed
(c) All pipes and hoses of air induction system connected
(d) All accessories switched OFF
(e) All vacuum lines properly connected
(f) SFI system wiring connectors fully plugged
(g) Ignition timing checked correctly
(h) Transmission in neutral position
2. CONNECT LEXUS HAND±HELD TESTER OR OBDII SCAN TOOL (See page EM±12)
3. INSPECT IDLE SPEED
(a) Race the engine speed at 2,500 rpm for approx. 90 seconds.
(b) Check the idle speed.
Idle speed: 700 ± 50 rpm
If the idle speed is not as specified, check the throttle body.
4. DISCONNECT LEXUS HAND±HELD TESTER OR OBDII SCAN TOOL

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.

IN04T±08
Vehicle Brought to Workshop
Customer Problem
Analysis
Symptom Confirmation
and Diagnostic Trouble
Code Check
Symptom Simulation
Diagnostic Trouble
Code Chart
Problem Symptoms Table
Circuit Inspection or Parts
Inspection
Repair
Confirmation Test
End 1
2
43
5
6
7
8Ask the customer about the conditions and the
environment when the problem occurred.1
Confirm the symptoms and the problem conditions,
and check the diagnostic trouble codes.
(When the problem symptoms do not appear
during confirmation, use the symptom simulation
method described later on.)2, 3
Check the results obtained in Step 2, then confirm
the inspection procedure for the system or the part
which should be checked using the diagnostic
trouble code chart or the problem symptoms table.4, 5, 6
Check and repair the affected system or part in
accordance with the instructions in Step 6. 7
After completing repairs, confirm that the problem
has been eliminated.
(If the problem is not reproduced, perform the
confirmation test under the same conditions and
in the same environment as when it occurred for
the first time.)8
± INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN±21
21 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
HOW TO PROCEED WITH TROUBLESHOOTING
Carry out troubleshooting in accordance with the procedure on the following page. Here, only the basic pro-
cedure is shown. Details are provided in Diagnostics section, showing the most effective methods for each
circuit. Confirm the troubleshooting procedures first for the relevant circuit before beginning troubleshooting
of that circuit.

Important Points in the Customer Problem Analysis

What ±±±±± Vehicle model, system name

When ±±±±± Date, time, occurrence frequency

Where ±±±±± Road conditions

Under what conditions? ±±±±± Running conditions, driving conditions, weather conditions

How did it happen? ±±±±± Problem symptoms
(Sample) Engine control system check sheet.
ENGINE CONTROL SYSTEM Check Sheet
Customer's Name
Driver's Name
Data Vehicle
Brought in
License No.
Model and Model
Year
Frame No.
Engine Model
Odometer Reading
km
miles
Problem Symptoms
Engine does
not Start
Difficult to
Start
Poor Idling
Poor
Drive ability
Engine Stall
Others
Engine does not crankNo initial combustionNo complete combustion
Engine cranks slowly
Other
Incorrect first idleIdling rpm is abnormalHigh ( rpm)Low ( rpm)
Rough idling
Other
HesitationBack fireMuffler explosion (after±fire)Surging
Knocking
Other
Soon after startingAfter accelerator pedal depressed
After accelerator pedal released
During A/C operation
Shifting from N to D
Other
Data Problem
ConstantSometimes ( times per day/month)
Inspector's
Name
CUSTOMER PROBLEM ANALYSIS CHECK
IN±22± INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
22 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
1. CUSTOMER PROBLEM ANALYSIS
In troubleshooting, the problem symptoms must be confirmed accurately and all preconceptions must be
cleared away in order to give an accurate judgment. To ascertain just what the problem symptoms are, it is
extremely important to ask the customer about the problem and the conditions at the time it occurred.
Important Point in the Problem Analysis:
The following 5 items are important points in the problem analysis. Past problems which are thought to be
unrelated and the repair history, etc. may also help in some cases, so as much information as possible should
be gathered and its relationship with the problem symptoms should be correctly ascertained for reference
in troubleshooting. A customer problem analysis table is provided in Diagnostics section for each system
for your use.