Page 235 of 1111

BE0GC±05
BE±196
± BODY ELECTRICALAUDIO SYSTEM
2497 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
TROUBLESHOOTING
NOTICE:
When replacing the internal mechanism (computer part) of the audio system, be careful that no part
of your body or clothing comes in contact with the terminals of the leads from the IC, etc. of the re-
placement part (spare part).
HINT:
This inspection procedure is a simple troubleshooting which should be carried out on the vehicle during sys-
tem operation and was prepared on the assumption of system component troubles (except for the wires and
connectors, etc.).
Always inspect the trouble taking the following items into consideration.
Open or short circuit of the wire harness
Connector or terminal connection fault
For audio systems with anti±theft system, troubleshooting items marked ( * ) indicate that ºTrou-
bleshooting for ANTI±THEFT SYSTEMº should be carried out first.
ProblemNo.
RadioRadio not operating when power switch turned to 'ON'.1
Display indicates when power switch turned to 'ON', but no sound (including
'noise') is produced.2
Noise present, but AM ± FM not operating.3
Any speaker does not work.4
Any AM or FM does not work.5
Few preset turning bands.5
Reception poor.6
Sound quality poor.7
Preset memory disappears.8
Tape PlayerCassette tape cannot be inserted.9
Cassette tape inserted, but no power.10
Power coming in, but tape player not operating.11
Any speaker does not work.12
Sound quality poor.13
Tape jammed, malfunction with tape speed or auto±reverse.14
Cassette tape will not eject.15
CD PlayerCD cannot be inserted.16
CD inserted, but no power.17
Power coming in, but CD player not operating.18
Sound jumps.19
Sound quality poor (Volume faint).20
Any speaker does not work.21
CD will not be ejected.22
Power AmplifierNo power coming in.23
Power coming in, but power amplifier not operating.24
Any speaker does not work.25
NoiseNoise occurs26
Noise produced by vibration or shock while driving.27
Noise produced when engine starts.28
The term ºAMº includes LW,MW and SW, and the term ºFWº includes UKW.
Page 236 of 1111

V08418
Turn ignition Key from LOCK position to ACC position.
Troubleshooting for ANTI±THEFT SYSTEM
Display A:
ID Number is set.Display E:
ANTI±THEFT SYSTEM opera-
tion condition. (ID number input
error 10 times or more.)Display B
ºSECº display disappears after 1
second.Radio switch ON.
Take to designated radio
service station.Display BDisplay D
Refer to each
malfunction item.Normal
operation.
Radio switch ON. Normal operation.
Cancel ID number, refer to each malfunction item.
Ye s
No
OK
NG
ANTI±THEFT SYSTEM operation condition. (ID number input error 9 times or less.)
Input ID number to cancel ANTI±THEFT SYSTEM, and check display.
Display A"B Display B Display E
Display C"A
Radio switch ON.Refer to each
malfunction item.Take to designated
radio service station.ANTI±THEFT SYSTEM not can-
celled. (ID number input error 10
times or less.)
Display D
ANTI±THEFT SYSTEM cancelled.
Check audio system again.Normal operation.
OK
NG
Cancel ID number, refer to each malfunction item.
Liquid Crystal Display (LCD) or VFD for Audio System
Display ºAº Display ºBº Display ºCº
Display ºDº Example:Display ºEº
2 DIN Type
1 DIN TypeBlank
No Illumination
2 DIN Type
1 DIN Type 2 DIN Type
1 DIN Type Error Times2 DIN Type 1 DIN Type
Radio Display
1 DIN Type 2 DIN Type
HINT:
Refer to Owner's Manual for operation details of ANTI±THEFT SYSTEM.
When the ID number has been cancelled, reset the same number after completing the operation, or
inform the customer that it has been cancelled.
± BODY ELECTRICALAUDIO SYSTEM
BE±197
2498 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
Page 240 of 1111
5 RadioANY AM OR FM DOES NOR WORK
FEW PRESET TUNING BANDS
Problem with radio wave signals or location?
Are both AM and FM defective?Radio assembly faulty.
Go to No.16
Is tape player operating normally? Radio assembly faulty.
Is power for the antenna being output from the radio assembly?
Hiss noise from speaker? Temporarily install another speaker. Functions OK?
Radio assembly faulty. Recheck system after repair.Speaker faulty.
Power amplifier faulty.
Recheck system after repair. Poor signals, poor location.
No
Ye s
Ye s No
No
NoYe s
Ye s
Ye s
Ye s
No
No
± BODY ELECTRICALAUDIO SYSTEM
BE±201
2502 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
Page 242 of 1111

7 Radio SOUND QUALITY POOR
Ye sNo
Ye s
NG
OK Is sound quality always bad?
Is tape player operating normally?Poor signals, poor location.
Radio assembly faulty.
Install properly.
Speaker faulty. Is tape player operating normally?
Is speaker properly installed?
Radio assembly or power amplifier faulty.
Recheck system after repair. Temporarily install another speaker. Functions OK?Is sound quality bad in certain
areas only?
Radio assembly or power
amplifier faulty.
Can cassette tape be inserted in tape player?
Check if RADIO No.1 fuse is OK?Radio assembly faulty.
Replace fuse.
+B wire harness faulty.
GND faulty.
Power amplifier faulty. 8 Radio PRESET MEMORY DISAPPEARSNo
Radio assembly faulty.
No
NoNo NoYe s
Ye s
Ye s
Power amplifier faulty.
Radio assembly faulty.Ye s
Ye sYe s
No
No
No NG
NG
OKOKYe s
Check if GND (wire harness side) of power amplifier
grounded normally? Is power supplied to +B terminal of power amplifier?
Check if GND (wire harness side) of radio assembly
grounded normally? Is power supplied to +B terminal of radio assembly?
± BODY ELECTRICALAUDIO SYSTEM
BE±203
2504 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
Page 367 of 1111
I04251
Combination Meter Wiring Circuit ± 2
Left Turn Indicator
Right Turn Indicator
Hi±beam Indicator
SRS Warning
Washer Level Indicator
Headlight leveling
Indicator
Malfunction
Indicator
VSC Warning
ABS Warning
VSC OFF Indicator
SLIP Indicator IG+IG+ IG+
IG+
IG+
IG+Combination Meter ECU
A14 A15 A16 A13 A12 B18 A10 to HEAD FuseB15B3B2
A7
B12Headlight Dimmer Switch
Airbag Sensor Assembly
Washer Fluid Level
Warning Switch
Healight Leveing
Contorl ECU
ECM
ABS, TRAC and
VSC ECU Turn Singal
Flasher RelayODO/TRIP Switch
RESET Switch to Combination Meter ECU
to Combination Meter ECUU8
U3
U10
U9
U4
SRS +B BE±84
± BODY ELECTRICALCOMBINATION METER
2385 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
Page 368 of 1111

Clock (Passenger seat belt warning light)
Tilt and telescopic ECU
Fuel main sender gauge
Fuel sub sender gauge
ABS, TRAC and VSC ECU (Speed signal)
Speed control unit
Headlight dimmer switch
Ground
Window washer level warning switch
Body control No.2 ECU
ECM
ABS, TRAC and VSC ECU (VSC warning light)
ABS, TRAC and VSC ECU (SLIP warning light)
ABS, TRAC and VSC ECU (TRAC OFF warning light)
ABS, TRAC and VSC ECU (ABS warning light)
ABS, TRAC and VSC ECU (Brake warning light)
GAUGE fuse
Turn signal flasher (Left turn side)
Turn signal flasher (Right turn side)
Light control rheostat (+B)
Light control rheostat (Signal)
Light control rheostat (Ground)
PANEL fuse
Airbag sensor assembly
MPX+B fuse
DOME+B fuse
HEAD±RH fuse
Igniter
Headlight beam leveling control ECU
Ground
Telltale light assembly (IG+)
Telltale light assembly (ODO/TRIP switch)
Telltale light assembly (Right turn signal)
Telltale light assembly (RESET switch)
Telltale light assembly (Left turn signal)
GroundWiring connector side No.1
1
1
2
3
4
5
6
7
8
10
11
12
13
14
15
16
17
1 1
1
2
3
4
5
6
9
12
13
14
15
16
18
22
1 1
1
3
4
8
9
10 U B A
± BODY ELECTRICALCOMBINATION METER
BE±85
2386 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
Page 370 of 1111
I04252
Engine
Coolant
Temperature
Receiver
Gauge
Tachometer
Speedometer
Fuel
Receiver
GaugeRight Turn Indicator Left Turn Indicator
ODO/TRIP Switch
RESET Switch TECOS+
TESIN+
TECOS± TESIN±
TACOS+
TASIN±
TASIN+
TACOS±
SPCOS±
SPSIN+
SPSIN±
SPCOS+
FUCOS±
FUSIN+TURN L
Power
Earth
TURN R
ODO/TRIP
RESET
HEAT±
Signal
Earth
Thermistor
SRS +B
C/C ±
C/C +
HEAT±
SRS +B Power
Earth O1
O2
O3
O4
P1
P2
P3
P4
Q1
Q2
Q3
Q4
R1
R2
R3G2 G1
G3
G4
G5
G6
G7
G8
L1
L2
L3
L4
L8
L12
K1
K3
K4
R4FUSIN±
FUCOS+C/C ±
C/C +K8
K12 Combination Meter ECU Meter Circuit Plate ± 1
± BODY ELECTRICALCOMBINATION METER
BE±87
2388 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
Page 378 of 1111
I04081
Connector ºGº
Connector ºUº
I04082
± BODY ELECTRICALCOMBINATION METER
BE±95
2396 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
4. INSPECT COMBINATION METER CIRCUIT PLATE
From combination meter ECU to telltale light assem-
bly:
Disconnect connector ºGº and ºUº from the meter circuit plate
and inspect the connectors on the wire harness side as follows.
Tester connectionSpecified condition
G1 ± U9Continuity
G3 ± U1Continuity
G5 ± U10Continuity
G6 ± U4Continuity
G7 ± U3Continuity
G8 ± U8Continuity
If circuit is not as specified, replace the circuit plate.
5. INSPECT TELLTALE LIGHT ASSEMBLY CONTINUITY
Switch positionTester connectionCondition
ODO/ TRIP switch Free3 ± 10No continuity
ODO/ TRIP switch
Pushed in3 ± 10Continuity
RESET switch Free8 ± 10No continuity
RESET switch Pushed in8 ± 10Continuity
Turn signal switch RIGHT4 ± 10Continuity
Turn signal switch LEFT9 ± 10Continuity
If continuity is not as specified, replace the telltale light assem-
bly.