1991 LEXUS SC400 audio

10RadioVOLUME REMAINS AT MAXIMUM LEVEL
A. without CD player type
Wire harness faulty.Radio receiver assembly faulty.
Is tape player operating normally?
Is there continuity between the following terminals
with connector disconnected?

Radio receiver amplifier B1 ± Power switch 14

Radio receiver amplifier 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 changes from 0 to 50 k
?
B. with CD player type
Wire harness faulty.
Radio receiver assembly faulty.
Is tape player operating normally?
Is there continuity between the following terminals
with connector disconnected?

Radio receiver amplifier B1 ± Power switch 14

Radio receiver amplifier 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 changes from 0 to 50 k ?
±
BODY ELECTRICAL SYSTEM AUDIO SYSTEMBE±233
WhereEverybodyKnowsYourName

11Tape playerCASSETTE TAPE CANNOT BE INSERTED
A. without CD player type
Wire harness faulty. Radio receiver assembly faulty.
Is there continuity between the following terminals
with connector connected?

Radio receiver amplifier A3 ± ground

Radio receiver amplifier A4 ± ground
Radio receiver assembly faulty.
Is there continuity between the following terminals
with connector disconnected?


Radio receiver assembly A7 ± ground Replace fuse.
Wire harness faulty.Remove foreign object.
Is there a foreign object inside tape player?
Is radio operating normally?
Check if RADIO No. 1 and RADIO No. 2 fuses
are OK.
BE±234±
BODY ELECTRICAL SYSTEM AUDIO SYSTEM
WhereEverybodyKnowsYourName

B. with CD player type
Wire harness faulty. Radio receiver assembly faulty.
Is there continuity between the following terminals
with connector connected?

Radio receiver amplifier A3 ± ground

Radio receiver amplifier A4 ± ground
Power amplifier faulty. Is there continuity between the following terminals
with connector disconnected?


Radio receiver assembly A11 ± ground Replace fuse.
Wire harness faulty.
Remove foreign object.
Is there a foreign object inside tape player?
Is radio operating normally?
Check if RADIO No.1 and RADIO No.2 fuses are OK
Wire harness faulty.Radio receiver assembly faulty.
Is there continuity between the following terminals
with connector disconnected?

Radio receiver assembly A11 ± Power amplifier A11
Is there continuity between the following terminals
with connector disconnected?

Power amplifier B7±ground.
±
BODY ELECTRICAL SYSTEM AUDIO SYSTEMBE±235
WhereEverybodyKnowsYourName

12Tape playerCASSETTE TAPE WILL NOT EJECT
A. without CD player type
Is there battery voltage between the following ter-
minals with connector connected?

Radio receiver amplifier A3 ± ground

Radio receiver amplifier A4 ± ground Replace fuse.
Wire harness faulty.
Wire harness faulty.
Is radio operating normally?
Check if RADIO No.1 and RADIO NO.2 fuses are OK Is tape player operating normally?
Radio receiver assembly faulty
Is there continuity between the following terminals
with connector disconnected?


Radio receiver amplifier A7 ± ground Cassette tape is
jammed or radio receiv-
er assembly faulty.
Radio receiver assem-
bly faulty.
BE±236±
BODY ELECTRICAL SYSTEM AUDIO SYSTEM
WhereEverybodyKnowsYourName

B. with CD player
Is there battery voltage between the following ter-
minals with connector connected?

Radio receiver amplifier A3 ± ground

Radio receiver amplifier A4 ± ground Replace fuse.
Wire harness faulty.
Is radio operating normally?
Check if RADIO No.1 and RADIO NO.2 fuses are OK Is tape player operating normally?
Power amplifier faulty.
Is there continuity between the following terminals
with connector disconnected?


Radio receiver amplifier A11 ± ground Cassette tape is
jammed or radio receiv-
er assembly faulty.
Radio receiver assem-
bly faulty.
Wire harness faulty. Wire harness faulty.Radio receiver assembly faulty.
Is there continuity between the following terminals
with connector disconnected?

Radio receiver amplifier A11 ± Power amplifier A11
Is there continuity between the following terminals
with connector disconnected?

Power amplifier B7 ± ground
±
BODY ELECTRICAL SYSTEM AUDIO SYSTEMBE±237
WhereEverybodyKnowsYourName

13Tape playerDISPLAY INDICATES, BUT NO SOUND IS
PRODUCED (EXCEPT WOOFER)
A. without CD player type
Is radio operating normally?Radio receiver assembly faulty.
Radio receiver assembly faulty. Is there continuity between the following terminals
with connector disconnected?


Radio receiver amplifier B1 ± Power switch 14

Radio receiver amplifier B3 ± Power switch 11
When the volume switch is turned from minu-
mum to maximum, does resistance between
terminal B1±B3 of radio receiver assembly
change from 0 to 50 k
?
is resistance value approx. 50 k  between ter-
minals B3±B6 of radio receiver assembly? Is there continuity between the following terminals
with connector disconnected?


Radio receiver amplifier B6 ± Power switch 13
Power switch faulty. Wire harness faulty. Power switch faulty. Wire harness faulty.
BE±238±
BODY ELECTRICAL SYSTEM AUDIO SYSTEM
WhereEverybodyKnowsYourName

B. with CD player type
Is radio operating normally?Radio receiver assembly faulty.
Is there continuity between the following terminals
with connector disconnected?

Radio receiver amplifier B1 ± Power switch 14

Radio receiver amplifier B3 ± Power switch 11
When the volume switch is turned from minu-
mum to maximum, does resistance between
terminal B1±B3 of radio receiver assembly
change from 0 to 50 k
?
is resistance value about 50 k  between termi-
nals B3±B6 of radio receiver assembly? Is there continuity between the following terminals
with connector disconnected?


Radio receiver amplifier B6 ± Power switch 13
Power switch faulty. Wire harness faulty.
Power switch faulty.
Wire harness faulty.
Is there continuity between the following terminals
with connector disconnected?

Radio receiver amplifier A1 ± Power switch A6
Radio receiver as-
sembly faulty. Wire harness faulty.
Wire harness faulty.
Power amplifier faulty. Wire harness faulty.
Is there continuity between the following terminals
with connector disconnected?

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


Power amplifier A14 ± ground

Power amplifier B10 ± ground
Is there continuity between the following terminals
with connector disconnected?

Power amplifier A7 ± ground
±
BODY ELECTRICAL SYSTEM AUDIO SYSTEMBE±239
WhereEverybodyKnowsYourName

14Tape playerANY SPEAKER DOES NOT WORK (EXCEPT
WOOFER)
A. without CD player type
Is there continuity between the following terminals
with connector disconnected?

Fr: Radio receiver assembly A1±FR speaker 1
Radio receiver assembly A5±FR speaker 2

FL: Radio receiver assembly A2±FL speaker 1
Radio receiver assembly A6±FL speaker 2

RR: Radio receiver assembly C1±RR speaker 1
Radio receiver assembly C3±RR speaker 2

RL: Radio receiver assembly C2±RL speaker 1
Radio receiver assembly C6±RL speaker 2
Is there continuity between the following terminals
with connector disconnected?

FR: Radio receiver assembly A1±ground
Radio receiver assembly A5±ground

FL: Radio receiver assembly A2±ground
Radio receiver assembly A6±ground

RR: Radio receiver assembly C1±ground
Radio receiver assembly C3±ground

RL: Radio receiver assembly C2±ground
Radio receiver assembly C6±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 tape player operating normally?
Temporarily install another speaker.
Functions OK?
Radio receiver assembly faulty.
BE±240±
BODY ELECTRICAL SYSTEM AUDIO SYSTEM
WhereEverybodyKnowsYourName