LEXUS GS400 2000 Service Repair Manual

24 Power AmplifierPOWER COMIMG IN, BUT WOOFER (POWER) AMPLIFIER NOT
OPERATING
+ B wire harness faulty.
GND faulty.
Power amplifier faulty.
Speaker wire harness faulty. GND faulty. Is tape player operating normally?
Check if RAD±No.2 fuse is OK?Ye s
NG
No OK No
No
No
No OK
OK
OK Ye s
Ye s
Ye s
Ye sNG
NG
NG Check if RAD±No.1 fuse is OK?
Radio assembly faulty. Recheck system after repair.Replace fuse.
ACC wire harness faulty. Radio assembly faulty.
Replace fuse.
Is there continuity in speaker wire harness?
Temporarily install another speaker. Functions OK?
Hiss noise from speaker?Ye s
Ye s NoNo
No Ye sPower amplifier faulty.
Power amplifier faulty.
Recheck system after repair. Speaker faulty.
Is power supplied to ACC terminal of power amplifier?
Check if GND (wire harness side) of power amplifier
grounded normally? Is power supplied to +B terminal of power amplifier?
Is power supplied to ACC terminal of radio assembly?
Is power supplied to +B terminal of radio assembly?
Check if GND (wire harness side) of radio assembly
grounded normally? BE±212
± BODY ELECTRICALAUDIO SYSTEM
2513 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)

CD player faulty.
Power amplifier faulty.
Recheck system after repair. Temporarily install another speaker.
Function OK?25 Power Amplifier ANY SPEAKER DOES NOT WORK
Speaker wire harness faulty.
Speaker faulty. Is hiss noise produced by non±functioning speaker?
Does continuity exist in speaker wire harness? Is radio operating normally?
Ye sYe s
Ye s
Ye s No
No
NoNoRadio assembly faulty.
Recheck system after repair.
± BODY ELECTRICALAUDIO SYSTEM
BE±213
2514 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)

26 Noise NOISE OCCURS
No
Ye s
NG
OK Does the noise occur only in the radio?
Does the noise occur in a particular place?
Is there any additional installation part
around the glass imprinted antenna?
(Sun shade film, telephone antenna etc.)
Does the noise occur even pulling out the
antenna cord from the radio?
Does the noise occur even after pulling out the
antenna terminal on the glass surface?
Isn't there any adhesive (Butyl rubber)
stuck on the bases of the antenna
terminal, defogger terminal and bus bar?
Check the grounding of the antenna,
antenna cord, coke coil, and noise filter.
(See page BE±190) Does the noise occur even after pulling out
the defogger terminal?
Does the condition get better by replacing
the antenna cord.
Noise rediates directly to the antenna from the
generation source. Does the condition get better by replacing
the choke coil?
Replace the antenna cord. Replace the choke coil. Interfering noise from the defogger line
and choke coil.
Grounding failure. Failure of glass installation.
Must plane the butyl rubber. Noise mixing into the antenna cable. Check the radio. Influence of the film or the noise radiation
of the additional installation part. Does the noise stop by removing it? An electric environment.Refer to No.27. (It occurs in the cassette and CD.)
Ye s
Ye s
Ye s
Ye s
Ye s
Ye s
Ye s
Ye s No
No
No
No
No
No
No
No
BE±214
± BODY ELECTRICALAUDIO SYSTEM
2515 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)

27 Noise NOISE PRODUCED BY VIBRATION OR SHOCK WHILE DRIVING
No
Ye s Is speaker properly installed?
Noise is produced from static eletricity accumulating in the vehicle body. With vehicles stationary lightly tap each system.
Is noise produced?Install properly.
Each system faulty. Is speaker properly installed?
No
No Ye s
Ye s
28 Noise NOISE PRODUCED WHEN ENGINE STARTS
NoYe s Whistling noise which becomes high±pitched when
accelerator strongly depressed, disappears shortly
after engine stops.Generator noise.
A/C noise.
Fuel gauge noise.
Horn noise.
Ignition noise.
Turn signal noise.
Washer noise.
Engine coolant temp. gauge noise.
Wiper noise. Whining noise occurs when A/C is operating.
Scratching noise occurs during sudden acceleration, driving on rough
roads or when ignition switch is turned ON.
Clicking sound is heard when horn button is pressed, then
released. Whirring/grating sound is heard when pushed
continuously.
Murmuring sound stops when engine stops.
Tick±tack noise occurs in co±ordination with blinking
offlasher.
Noise occurs during window washer operation.
Scratching noise occurs while engine is running,
and continues a while even after engine stops.
Scraping noise in line with wiper beat.
Other type of noiseYe s
Ye s
Ye s
Ye s
Ye s
Ye s
Ye s
Ye s No
No
No
No
No
No
No
No
± BODY ELECTRICALAUDIO SYSTEM
BE±215
2516 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)

BE04S±04
I05031
± BODY ELECTRICALPOWER SOURCE
BE±21
2322 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
INSPECTION
1. INSPECT ENGINE ROOM NO.1 JUNCTION BLOCK
CIRCUIT
(a) Remove the fuse from the junction block and inspect the
connector on junction block side.
Fuse Tester connectionConditionSpecified condition
MAIN 2 ± GroundConstantBattery positive voltage
ABS NO.1 4 ± GroundConstantBattery positive voltage
ALT 6 ± GroundConstantBattery positive voltage
ABS 8 ± GroundConstantBattery positive voltage
H±LP CLN 10 ± GroundConstantBattery positive voltage
RAD NO.1 12 ± GroundConstantBattery positive voltage
ALT±S 14 ± GroundConstantBattery positive voltage
EFI 16 ± GroundConstantBattery positive voltage
TURN HAZ 18 ± GroundConstantBattery positive voltage
TEL 20 ± GroundConstantBattery positive voltage
AM2 22 ± GroundConstantBattery positive voltage
ETCS 24 ± GroundConstantBattery positive voltage
HORN 26 ± GroundConstantBattery positive voltage
MPX±B 27 ± GroundConstantBattery positive voltage

BE±22
± BODY ELECTRICALPOWER SOURCE
2323 Author: Date:
2000 LEXUS GS300/GS400 (RM718U) ECU±B1 30 ± Ground
ConstantBattery positive voltage
HTR 31 ± GroundConstantBattery positive voltage
FAN MAIN 33 ± GroundConstantBattery positive voltage
CDS FAN 35 ± GroundIgnition switch ONBattery positive voltage
RAD FAN 35 ± GroundIgnition switch ONBattery positive voltage
H±LP R LWR 38 ± GroundLight control switch HEADBattery positive voltage
H±LP L LWR 38 ± GroundLight control switch HEADBattery positive voltage
H±LP R UPR 38 ± GroundLight control switch HEADBattery positive voltage
H±LP L UPR 42 ± GroundLight control switch HEADBattery positive voltage
If the circuit is not as specified, inspect the circuits connected
to other parts.
(b) Remove the relay from the junction block and inspect the
connector on junction block side.
Relay Tester connectionConditionSpecified condition
H±LP 44 ± GroundConstantBattery positive voltage
H±LP 46 ± GroundConstantBattery positive voltage
ST 48 ± GroundConstantContinuity
ST 51 ± GroundConstantBattery positive voltage
EFI MAIN 53 ± GroundConstantContinuity
EFI MAIN 55 ± GroundConstantBattery positive voltage
If the circuit is not as specified, inspect the circuits connected
to other parts.

I05032
± BODY ELECTRICALPOWER SOURCE
BE±23
2324 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
2. INSPECT ENGINE ROOM No.3 RELAY BLOCK CIR-
CUIT
Remove the relay from the relay block and inspect the connec-
tor on relay block side.
Fuse Tester connectionConditionSpecified condition
FAN NO.1 3 ± GroundIgnition switch ONBattery positive voltage
FAN NO.2 8 ± GroundIgnition switch ONBattery positive voltage
A/C COMP 13 ± GroundIgnition switch ONBattery positive voltage
FAN NO.3 17 ± GroundIgnition switch ONBattery positive voltage
DIMMER 20 ± GroundConstantBattery positive voltage
If the circuit is not as specified, inspect the circuits connected
to other parts.

I05033
BE±24
± BODY ELECTRICALPOWER SOURCE
2325 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
3. INSPECT ENGINE ROOM No.2 RELAY BLOCK CIR-
CUIT
Remove the relay from the relay block and inspect the connec-
tor on relay block side.
Relay Tester connectionConditionSpecified condition
HORN 1 ± GroundConstantBattery positive voltage
HORN 2 ± GroundHorn switch ONContinuity
HORN 4 ± GroundConstantBattery positive voltage
ABS SOL 5 ± GroundConstantBattery positive voltage
ABS SOL 6 ± GroundConstantContinuity
TRC MTR 11 ± GroundConstantBattery positive voltage
ABS MTR 15 ± GroundConstantBattery positive voltage
If the circuit is not as specified, inspect the circuits connected
to other parts.

I05034
± BODY ELECTRICALPOWER SOURCE
BE±25
2326 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
4. INSPECT DRIVER SIDE JUNCTION BLOCK CIRCUIT

BE±26
± BODY ELECTRICALPOWER SOURCE
2327 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(a) Remove the fuse from the junction block and inspect the
connector on junction block side.
Fuse Tester connectionConditionSpecified condition
AM1 1 ± GroundConstantBattery positive voltage
WASHER 3 ± GroundIgnition switch ONBattery positive voltage
FOG 5 ± GroundConstantBattery positive voltage
TAIL 7 ± GroundLight control switch TAIL or HEADBattery positive voltage
SRS±ACC 9 ± GroundIgnition switch ACC or ONBattery positive voltage
GAUGE 11 ± GroundIgnition switch ONBattery positive voltage
FUEL OPN 13 ± GroundConstantBattery positive voltage
D FR DOOR 15 ± GroundConstantBattery positive voltage
PANEL 17 ± GroundLight control switch TAIL or HEADBattery positive voltage
HTR 19 ± GroundIgnition switch ONBattery positive voltage
SRS±B 21 ± GroundConstantBattery positive voltage
P/SEAT (D) 23 ± GroundConstantBattery positive voltage
RAD NO.2 25 ± GroundIgnition switch ACC or ONBattery positive voltage
WIP 27 ± GroundIgnition switch ONBattery positive voltage
OBD 29 ± GroundConstantBattery positive voltage
STOP 31 ± GroundConstantBattery positive voltage
CIG 33 ± GroundIgnition switch ACC or ONBattery positive voltage
ECU±IG 35 ± GroundIgnition switch ONBattery positive voltage
ST 37 ± GroundIgnition switch ONBattery positive voltage
IGN 39 ± GroundIgnition switch ONBattery positive voltage
D RR DOOR 41 ± GroundConstantBattery positive voltage
If the circuit is not as specified, inspect the circuits connected
to other parts.
(b) Remove the relay from the junction block and inspect the
connector on junction block side.
Relay Tester connectionConditionSpecified condition
Fog light 43 ± GroundConstantBattery positive voltage
Fog light 44 ± GroundConstantContinuity
Fog light 46 ± GroundLight control switch HEADBattery positive voltage
Taillight 47 ± GroundConstantBattery positive voltage
Taillight 48 ± GroundConstantContinuity
Taillight 50 ± GroundConstantContinuity
If the circuit is not as specified, inspect the circuits connected
to other parts.