LEXUS SC400 1991 Service Repair Manual

B. with CD player type
HINT: The part names and terminals indicated in brackets ( ) are for model\
s with a Nakamichi system.
Is radio operating normally?Radio receiver assembly faulty.
Woofer faulty.
Wire harness faulty.
Is there battery voltage between the following
terminals with connector connected?

Woofer amplifier 3 (Power amplifier C3) ± ground

Woofer amplifier 4 (Power amplifier C4) ± ground
Temporarily install another woofer.
Functions OK? Radio receiver assembly faulty Wire harness faulty.
Wire harness faulty.
Wire harness faulty.
Wire harness faulty.
Is there continuity between the following terminals
with connector disconnected?


Woofer amplifier 9 (Power amplifier C9) ±
Woofer 2

Woofer amplifier 10 (Power amplifier C10) ±
Woofer 1
Is there continuity between the following terminals
with connector disconnected?

Woofer amplifier 9 (Power amplifier C9) ± ground

Woofer amplifier 10 (Power amplifier C10) ±
ground
Is there battery voltage between the following
terminals with connector connected?


Woofer amplifier 6 (Power amplifier C6) ± ground
Is there continuity between the following terminals
with connector connected?

Woofer amplifier 7 (Power amplifier C7) ± ground
±
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17Tape playerWOOFER VOLUME FAINT
A. without CD player type
Is radio operating normally?Radio receiver assembly faulty.
Wire harness faulty.
Is there continuity between the following terminals
with connector connected?

Radio receiver assembly D1 ± Woofer amplifier 1

Radio receiver assembly D5 ± Woofer amplifier 5
Wire harness faulty.
Woofer amplifier faulty.
Radio receiver assembly faulty.
Temporarily install another woofer amplifier.
Funcitions OK? Is there continuity between the following terminals
with connector disconnected?


Radio receiver assembly D1 ± ground

Radio receiver assembly D5 ± ground
B. with CD player type
HINT: The part names and terminals indicated in brackets ( ) are for model\
s with a Nakamichi system.
Is radio operating normally?
Radio receiver assembly faulty.
Wire harness faulty.
Is there continuity between the following terminals
with connector connected?

Radio receiver assembly D1 ± Woofer
amplifier 1 (Power amplifier C1)

Radio receiver assembly D5 ± Woofer
amplifier 5 (Power amplifier C5)
Wire harness faulty.
Woofer amplifier faulty.
Radio receiver assembly faulty. Temporarily install another woofer amplifier.
Funcitions OK? Is there continuity between the following terminals
with connector disconnected?

Radio receiver assembly D1 ± ground

Radio receiver assembly D5 ± ground
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18Tape playerSOUND QUALITY POOR
A. without CD player type
Is radio operating normally?Is speaker properly installed?
Temporarily install another speaker.
Functions OK?
Radio receiver assembly faulty. Operates normally after cleaning the heads?
Head dirty.
Radio receiver
assembly faulty.
Speaker installation faulty.
Speaker faulty.
B. with CD player type
Is speaker properly installed?
Temporarily install another speaker.
Functions OK?
Radio receiver assembly faulty. Speaker installation faulty.
Speaker faulty.
Power amplifier faulty.
Head dirty. Radio receiver as-
sembly faulty.
Temporarily install another power amplifier.
Functions OK?
Is radio operating normally?
Operates normally after cleaning the heads?
±
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19Tape playerVOLUME REMAINS AT MAXIMUM LEVEL
A. without CD player type
Is radio operating normally? Radio receiver assembly faulty.Wire harness faulty.
Is there continuity between the following terminals
with connector disconnected?

Radio receiver assembly B1 ± Power switch 14

Radio receiver assembly B3 ± Power switch 11
Power switch faulty.
Radio receiver assembly faulty. When the volume switch is turned from minu-
mum to maximum, does resistance between
terminal 11±14 of power switch change from 0
to 50 k
?
B. with CD player type
Is radio operating normally? Radio receiver assembly faulty.
Wire harness faulty.
Is there continuity between the following terminals
with connector disconnected?

Radio receiver assembly B1 ± Power switch 14

Radio receiver assembly B3 ± Power switch 11
Power switch faulty.
Radio receiver assembly faulty.
When the volume switch is turned from minumum
to maximum, does resistance between terminal
11±14 of power switch change from 0 to 50 k
?
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20CD playerMAGAZINE CANNOT BE INSERTED INTO AUTO
CHANGER
Is radio operating normally?
Is there battery voltage between the following termi-
nals with connector connected?

Radio receiver assembly C5 ± ground
Is there continuity between the following terminals
with connector disconnected?

CD auto changer A4 ± Radio receiver assembly C5
Is there continuity between the following terminals
with connector disconnected?

CD auto changer A9 ± ground
CD auto changer faulty. Wire harness faulty.
Radio receiver assembly faulty.
Go to No. 1.
Is there continuity between the following terminals
with connector disconnected?

CD autochanger A9 ± Radio receiver assembly C4
Wire harness faulty. Radio receiver as-
sembly faulty.
±
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21CD playerMAGAZINE IS INSERTED, BUT DISPLAY DOES
NOT INDICATE ºCDº
Is radio operating normally?
Is there battery voltage between the following
terminals with connector connected?

Radio receiver assembly C12 ± ground
Wire harness faulty.Radio receiver assembly faulty.
Go to No. 1.
Is there battery voltage between the following
terminals with connector connected?

Radio receiver assembly C12 ± CD auto
changer A3
Is there battery voltage between the following
terminals with connector connected?

Radio receiver assembly C3 ± CD auto changer
B1

Radio receiver assembly C8 ± CD auto changer
B3

Radio receiver assembly C9 ± CD auto changer
B2

Radio receiver assembly C10 ± CD auto changer
B10
Is there battery voltage between the following
terminals with connector disconnected?

Radio receiver assembly C3 ± ground

Radio receiver assembly C8 ± ground

Radio receiver assembly C9 ± ground

Radio receiver assembly C10 ± ground
Temporarily install another CD auto changer.
Functions OK? CD auto changer faulty. Wire harness faulty.
Wire harness faulty.
Radio receiver assembly faulty
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22CD playerDISPLAY INDICATES, BUT NO SOUND IS
PRODUCED (EXCEPT WOOFER)
Is radio operating normally?Wire harness faulty.
Is there battery voltage between the following ter-
minals with connector connected?

Power amplifier A14 ± ground

Power amplifier A10 ± ground
Wire harness faulty.
Is there battery voltage between the following ter-
minals with connector connected?


Power amplifier A6 ± ground
Is there battery voltage between the following ter-
minals with connector connected?

Power amplifier A7 ± ground Is there battery voltage between the following ter-
minals with connector disconnected?


Radio receiver assembly B6 ± Power switch 13.
Is there battery voltage between the following ter-
minals with connector disconnected?


Radio receiver assembly B1±Power switch 14

Radio receiver assembly B3±Power switch 11
Wire harness faulty.
Power switch faulty.
Wire harness faulty.
Radio receiver assem-
bly faulty. Wire harness faulty.
Power switch faulty.
Is resistance value about 50 k  between terminals
B3±B6 of radio receiver assembly?
Temporarily install another CD auto changer.
Functions OK? CD auto changer faulty.Is there continuity between the following terminals
with connector disconnected?


Radio receiver assembly A1±Power amplifier A6.
When the volume switch is turned from minimum to
maximum, does resistance between terminals
B1±B3 of radio receiver assembly changer from 0
to 50 k

Radio receiver assembly faulty.
Radio receiver assembly faulty.
±
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23CD playerANY SPEAKER DOES NOT WORK
(EXCEPT WOOFER).
Is there continuity between the following terminals
with connector disconnected?

Fr: Power amplifier B1±FR speaker 1
Power amplifier B5±FR speaker 2

FL: Power amplifier B2±FL speaker 1
Power amplifier B6±FL speaker 2

RR: Power amplifier B3±RR speaker 1
Power amplifier B4±RR speaker 2

RL: Power amplifier B8±RL speaker 1
Power amplifier B9±RL speaker 2
Is there continuity between the following terminals
with connector disconnected?

FR: Power amplifier B1±ground
Power amplifier B5±ground

FL: Power amplifier B2±ground
Power amplifier B6±ground

RR: Power amplifier B3±ground
Power amplifier B4±ground

RL: Power amplifier B8±ground
Power amplifier B9±ground Wire harness faulty


(The wire harness for the FR speaker passes
through the transceiver, so the transceiver side
should be checked) Wire harness faulty


(The wire harness for the FR speaker passes
through the transceiver, so the transceiver side
should be checked)
Speaker faulty. Radio receiver assembly faulty.
Is radio operating normally?
Temporarily install another speaker.
Functions OK? Wire harness faulty.
Wire harness faulty.
Is there continuity between the following terminals
with connector disconnected?


FR: Radio receiver assembly A7±Power amplifier
A1

FL: Radio receiver assembly A6±Power amplifier
A2

RR: Radio receiver assembly A15±Power amplifi-
er A7

RL: Radio receiver assembly A14±Power amplifi-
er A8
Is there continuity between the following terminals
with connector disconnected?

FR: Radio receiver assembly A7±ground

FL: Radio receiver assembly A6±ground

RR: Radio receiver assembly A15±ground

RL: Radio receiver assembly A14±ground
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Temporarily install another power amplifier.
Function is OK?Radio receiver assembly faulty. Power amplifier faulty.
24CD playerVOLUME FAINT (EXCEPT WOOFER)
Is radio operating normally?
When the volume switch is turned from minimum to
maximum, does resistance between terminals
B1±B3 of radio receiver assembly changer from 0
to 50 k 
Radio receiver assembly faulty.
Power switch faulty.
Wire harness faulty.
Power amplifier faulty.
Radio receiver assembly faulty.
*Is there battery voltage between the following
terminals with connector disconnected?


Radio receiver assembly D3 ± ground
Temporarily install another power amplifier.
Function is OK?
±
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25CD playerRH CHANNEL OR LH CHANNEL SPEAKER
VOLUME FAINT
Is there continuity between the following terminals
with connector disconnected?

RH: :Radio receiver assembly C1 ±
CD auto changer A1
:Radio receiver assembly C6 ±
CD auto changer A5

LH: Radio receiver assembly C2 ±
CD auto changer A2
:Radio receiver assembly C7 ±
CD auto changer A6 Radio receiver as-
sembly faulty.
Is radio operating normally?
Wire harness faulty.
Wire harness faulty.
Is there continuity between the following terminals
with connector disconnected?

RH: :Radio receiver assembly C1 ± ground
:Radio receiver assembly C6 ± ground

LH: :Radio receiver assembly C2 ± ground
:Radio receiver assembly C7 ± ground
Temporarily install another CD auto changer.
Functions OK? CD auto changer faulty.
Radio receiver assembly faulty. Power amplifier
faulty.
Temporarily install another power amplifier.
Functions OK.
BE±254±
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