LEXUS GS400 2000 Service Repair Manual

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)

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)

9 Tape Player CASSETTE TAPE CANNOT BE INSERTED
Ye s
No NG Is there a foreign object inside tape player?
Is auto search button radio operating normally?
Check if RADIO No.1 fuse is OK?
Radio assembly faulty.Radio assembly faulty. Remove foreign object.
Replace fuse.
+B wire harness faulty.
GND faulty.
Power amplifier faulty.
Power amplifier faulty. Ye s No
No
OK
Ye s
OK
Ye s
OKNG
No
NG
10 Tape Player CASSETTE TAPE INSERTED, BUT NO POWER
Is radio operating normal?
Check if RAD No.2 fuse is OK?
ACC wire harness faulty.
Check if RADIO No.1 fuse is OK?Radio assembly faulty.
Replace fuse.
Replace fuse.
+B wire harness faulty.
Power amplifier faulty.
Radio assembly faulty.No
No
No
No OK
OKYe s
Ye s
Ye sYe s
NG
NG 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?
Is power supplied to +B terminal of radio assembly? Is power supplied to ACC terminal of power amplifier?
Is power supplied to ACC terminal of radio assembly? BE±204
± BODY ELECTRICALAUDIO SYSTEM
2505 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)

11 Tape Player POWER COMING IN, BUT TAPE PLAYER NOT OPERATING
Ye s
NoRadio assembly faulty. Cassette tape faulty.
Speaker wire harness faulty.
Speaker faulty.
Power amplifier faulty.
Recheck system after repair. Ye s No
No
Ye s
Ye sNo No Function OK if different cassette tape inserted?
Is radio operating normally?
Does continuity exist in speaker wire harness?
Temporarily install another speaker.
Function OK?
Hiss noise from speaker?
Radio assembly faulty.
Recheck system after repair.Ye s
Radio assembly faulty.
Recheck system after repair. Radio assembly faulty.
No
No
No Ye sYe s
Ye s
Ye s No Is radio operating normally?
Speaker wire harness faulty.
Speaker faulty. Is hiss noise produced by non±functioning speaker.
Does continuity exist in speaker wire harness?
Temporarily install another speaker.
Function OK?
Radio assembly or power amplifier faulty.12 Tape Player ANY SPEAKER DOES NOT WORK
± BODY ELECTRICALAUDIO SYSTEM
BE±205
2506 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)

13 Tape Player SOUND QUALITY POOR (VOLUME FAINT)
Ye s
NoRadio assembly faulty. Cassette tape faulty.
Install properly.
Speaker faulty. Head dirty.
Ye s No
No
Ye sYe s
No No Function OK if different cassette tape inserted?
Is radio operating normally?
Is speaker properly installed?
Temporarily install another speaker.
Function OK?
Radio assembly faulty. Operates normally after cleaning the heads?
Ye s
Function OK if different tape (less than 120 mins.) is inserted?
Operates normally after cleaning the heads?
Radio assembly faulty. Is there a foreign object inside tape player?Cassette tape faulty.
Remove foreign object.
Head dirty. 14 TAPE JAMMED MALFUNCTION WITH TAPE SPEED OR AUTO±REVERSE
No
No
NoYe s
Ye s
Ye s 14
Tape PlayerTAPE JAMMED MALFUNCTION WITH TAPE SPEED OR AUTO±REVERSE BE±206
± BODY ELECTRICALAUDIO SYSTEM
2507 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)

15 Tape Player CASSETTE TAPE WILL NOT BE EJECTED
Radio assembly faulty. Is tape player operating normally?
Is auto search button of radio operating normally?
Check if RADIO No.1 fuse is OK?Cassette tape jammed.
Replace fuse.
+B wire harness faulty.
Power amplifier faulty. Ye s
Ye s
Ye sYe s
NoNo
No
No NG
OK
Radio assembly faulty.
16 CD Player CD CANNOT BE INSERTED
Ye s
No Is CD already inserted?
Eject CD.
Radio assembly faulty.
CD player faulty.
Replace fuse.
+B wire harness faulty. Check if RADIO No.1 fuse is OK?
Radio assembly faulty.
Is auto search button of radio operating normally?
NoNo Ye s
Ye sYe s
No OK
NG
OKOK
NGNG
Check if GND (wire harness side) of radio assembly
grounded normally? Is power supplied to +B terminal of power amplifier?
Is power supplied to +B terminal of radio receiver?
Is power supplied to +B terminal of power amplifier?Is power supplied to +B terminal
of CD player?
Check if GND (wire harness
side) of CD player grounded
normally?
± BODY ELECTRICALAUDIO SYSTEM
BE±207
2508 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)

17 CD Player CD INSERTED, BUT NO POWER
Radio assembly faulty.
Replace fuse. Check if RADIO No.2 fuse is OK? Is radio operating normally?
CD player faulty.
ACC wire harness faulty.
Power amplifier faulty.
Radio assembly faulty.No
No
NoNo Ye s
Ye s
Ye s
Ye s OKNG
18 CD Player POWER COMING IN, BUT CD PLAYER NOT OPERATING
Is CD inserted with correct side up?
Is radio operating normally?Insert correctly.
CD faulty.
Protective circuit in
operation. Function OK if different CD inserted?
Has sudden temperature change
occurred inside cabin?
CD player faulty.Is temperature inside cabin hot?
Speaker wire harness faulty.
Speaker faulty.
Power amplifier faulty.
Recheck system after repair. Dose continuity exist in speaker wire harness?
Temporarily install another speaker.
Functions OK?
Hiss noise from speaker?
Radio assembly faulty.
Recheck system after repair.No
Ye s Ye s
Ye s
Ye s
Ye s
Ye s Ye s
Ye s No
No
NoNo
No
No
No
Formation of
condensation
due to temp. changes.
Is power supplied to ACC terminal of power amplifier?
Is power supplied to ACC terminal of radio assembly?Is power supplied to ACC
terminal of CD player? BE±208
± BODY ELECTRICALAUDIO SYSTEM
2509 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)

CD Player SOUND JUMPS
19
CD player faulty. Does sound jump only during strong vibration?
Is CD player properly installed?
Functions OK if different CD inserted?
Has sudden temperature change occurred inside cabin?Jumping caused by vibration.
Install properly.
CD faulty.
Formation of condensation due to
temp. changes. Ye sYe s
Ye s
Ye s No No
No
No
20 CD Player SOUND QUALITY POOR (VOLUME FAINT)
Is radio operating normally?CD faulty. Function OK if different CD inserted?
Speaker faulty. Temporarily install another speaker.
Functions OK?Ye s
No
Is speaker property installed?CD player faulty.
Install properly. Ye s
Ye s Ye s No
NoNo
Radio assembly or CD player or power amplifier faulty.
± BODY ELECTRICALAUDIO SYSTEM
BE±209
2510 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)

CD player faulty.
Power amplifier faulty.
Recheck system after repair. Temporarily install another speaker.
Function OK?21 CD Player 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.
CD player faulty. 22 CD Player CD WILL NOT BE EJECTED
Is auto search button of radio
operating normally?
NoRadio assembly
faulty.
Replace fuse.
+B wire harness faulty.
Power amplifier faulty.
Radio assembly faulty. Check if RADIO No.1 fuse is OK?No
No
No Ye s
NG
OK
Ye s
Ye sYe s
Is power supplied to +B terminal of power amplifier?
Is power supplied to +B terminal of radio receiver?Is power supplied to +B terminal
of CD player? BE±210
± BODY ELECTRICALAUDIO SYSTEM
2511 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)

23 Power Amplifier NO POWER COMING IN
+ B wire harness faulty.
GND faulty.
Power amplifier or wire harness faulty.
Power amplifier or 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.Replace fuse.
ACC wire harness faulty. Radio assembly faulty.
Replace fuse.
Check if GND (wire harness side) of power amplifier
grounded normally?Is power supplied to ACC terminal of power amplifier?
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?
± BODY ELECTRICALAUDIO SYSTEM
BE±211
2512 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)