2000 LEXUS GS400 radio

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)

BE0GD±10
I01372
Ignition SwitchRadio Assembly Tweeter
Front Speakers
Rear Speakers
Tweeter
Radio Assembly LEXUS Navigatioin
System Woofer
Power Amplifier
(NAKAMICHI made)
Driver Side Junction Block

RAD NO.2 FuseEngine Room No.1
Junction Block

ECU±B1 Fuse

RAD NO.1 Fuse
Passenger Side
Junction Block

DOME Fuse CD Auto ChangerCD Magazine
Power Amplifier
(PIONEER made)
BE±216
± BODY ELECTRICALAUDIO SYSTEM
2517 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
LOCATION
The vehicle shown in this illustration is ºGS400º.
All components of ºGS300º other than the ones used for engine are same as ºGS400º.

BE0GE±03
I04310
Wire Harness Side
I04189
Wire Harness Side
Connector ºBº
Connector ºDº Connector ºCº Connector ºAº
± BODY ELECTRICALAUDIO SYSTEM
BE±217
2518 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
INSPECTION
1. Except NAKAMICHI made:
INSPECT CD AUTO CHANGER CIRCUIT
Disconnect connectors from CD auto changer and inspect the
connector on the wire harness side.
Tester connectionConditionSpecified condition
8 ± GroundConstantContinuity
5 ± GroundConstantBattery positive voltage
10 ± GroundIgnition switch LOCKNo voltage
10 ± GroundIgnition switch ACC or ONBattery positive voltage
If the circuit is not as specified, inspect the circuits connected
to other parts.
HINT:

Check the wire harness between the radio receiver as-
sembly and the CD auto changer.

Since the signals to and from the MUTE, R±, R+, L±, L+,
TX
± and TX+ terminals are serial signals, they cannot or-
dinarily be measured with a tester.
2. Except NAKAMICHI made:
INSPECT POWER AMPLIFIER CIRCUIT
Disconnect the connector from power amplifier and inspect the
connector on the wire harness side.
Tester connectionConditionSpecified condition
B7 ± GroundConstantContinuity
C12 ± GroundIgnition switch LOCK and radio switch ONNo voltage
C12 ± GroundIgnition switch ACC or ON and radio switch ONBattery positive voltage
B4 ± GroundConstantBattery positive voltage
If the circuit is not as specified, inspect the circuits connected
to other parts.

I04190
Wire Harness Side
Connector ºAº Connector ºBº BE±218
± BODY ELECTRICALAUDIO SYSTEM
2519 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
3. Except 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
A2 ± GroundConstantContinuity
A4 ± GroundConstantBattery positive voltage
A1 ± GroundIgnition switch LOCKNo voltage
A1 ± GroundIgnition switch ACC or ONBattery positive voltage
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.

I04188
Wire Harness Side
± BODY ELECTRICALAUDIO SYSTEM
BE±219
2520 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
4. NAKAMICHI made:
INSPECT CD AUTO CHANGER CIRCUIT
Disconnect connectors from CD auto changer and inspect the
connector on the wire harness side.
Tester connectionConditionSpecified condition
14 ± GroundConstantContinuity
4 ± GroundIgnition switch LOCKNo voltage
4 ± GroundIgnition switch ACC or ONBattery positive voltage
5 ± GroundConstantBattery positive voltage
If the circuit is not as specified, inspect the circuits connected
to other parts.
HINT:

Check the wire harness between the radio receiver as-
sembly and the CD auto changer.

Since the signals to and from the MUTE, R±, R+, L±, L+,
TX
± and TX+ terminals are serial signals, they cannot or-
dinarily be measured with a tester.

I04309
Wire Harness Side
Connector ºBº
Connector ºDº Connector ºCº Connector ºAº BE±220
± BODY ELECTRICALAUDIO SYSTEM
2521 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
5. NAKAMICHI made:
INSPECT POWER AMPLIFIER CIRCUIT
Disconnect the connector from power amplifier and inspect the
connector on the wire harness side.
Tester connectionConditionSpecified condition
A1 ± Ground
A4 ± Ground
D1 ± Ground
ConstantContinuity
A6 ± GroundIgnition switch LOCK and radio switch ONNo voltage
A6 ± GroundIgnition switch ACC or ON and radio switch ONBattery positive voltage
A2 ± GroundConstantBattery positive voltage
A5 ± GroundConstantBattery positive voltage
If the circuit is not as specified, inspect the circuits connected
to other parts.

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.)