1991 LEXUS SC400 CD player

B. with CD player type
Does radio operate normally when AM or FM
button is pushed?
Is there battery positive voltage between the
following terminals with connector connected?

Radio receiver assembly A3±ground

Radio receiver assembly A4±ground
Check if RADIO No.1 and RADIO No.2 fuses are OK.
Is therecontinuity between the following termi-
nals with connector disconnected?

Radio receiver assembly A11±ground Replace fuse.
Wire harness faulty
Radio receiver assembly faulty.
Wire harness faulty.
Wire harness faulty. Inspect power switch.
Wire harness faulty
Is there continuity voltage between the following
terminals with connector connected?


Radio receiver assembly B2±Power switch 12

Radio receiver assembly B3±Power switch 11
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?

Radio receiver assembly B7±ground
Power amplifier faulty.
±
BODY ELECTRICAL SYSTEM AUDIO SYSTEMBE±221
WhereEverybodyKnowsYourName

2Radio
DISPLAY INDICATES WHEN POWER SWITCH
TURNED TO ºONº, BUT NO SOUND (INCLUDING
ºNOISEº) IS PRODUCED (EXCEPT WOOFER)
A. without CD player type
Is there continuity between the following terminals
with connector disconnected?

Radio receiver assembly B1±Power switch 14

Radio receiver assembly B3±Power switch 11
Radio receiver assembly faulty.
Is tape player operating normally?
When the volume switch is turned from minimum
to maximum, does resistance between terminals
B1 ± B3 of radio receiver assembly change from
0 to 50 k .
Power switch faulty. Wire harness faulty.
Is resistance value approx. 50  between termi-
nals is B3±B6 of radio receiver assembly?
Radio receiver assembly faulty. Is there continuity between the following terminals
with connector disconnected?


Radio receiver assembly B6±Power switch 13
Power switch faulty. Wire harness faulty.
BE±222±
BODY ELECTRICAL SYSTEM AUDIO SYSTEM
WhereEverybodyKnowsYourName

B. with CD player type
Is there continuity between the following terminals
with connector disconnected?

Radio receiver assembly B1±Power switch 14

Radio receiver assembly B3±Power switch 11
Is tape player operating normally?
Power switch faulty.Wire harness faulty.
Is resistance value about 50 k
 between termi-
nals is B3±B6 of radio receiver assembly?
Wire harness faulty.
Is there continuity between the following terminals
with connector disconnected?

Radio receiver assembly A1±Power amplifier A6
Is there continuity between the following terminals
with connector disconnected?


Radio receiver assembly B6±Power switch 13
Power switch faulty.
Wire harness faulty.
Is there battery positive voltage between the follow-
ing terminals with connector connected?

Power amplifier A14±ground

Power amplifier B10±ground
Is there battery positive voltage between the follow-
ing terminals with connector connected?

Power amplifier A6±ground Radio receiver assembly faulty.
When the volume switch is turned from mini-
mum to maximum, does resistance between
terminals B1±B3 of radio receiver assembly
change from 0 to 50 k ?
Wire harness faulty.
Power amplifier faulty. Is there continuity between the following terminals
with connector disconnected?


Power amplifier B7±ground Radio receiver assem-
bly faulty.
Wire harness faulty.
±
BODY ELECTRICAL SYSTEM AUDIO SYSTEMBE±223
WhereEverybodyKnowsYourName

4RadioANY 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.
Finctions OK?
Radio receiver assembly faulty.
±
BODY ELECTRICAL SYSTEM AUDIO SYSTEMBE±225
WhereEverybodyKnowsYourName

Is there continuity between the following terminals
with connector disconnected?

Fr: Radio receiver assembly B1±FR speaker 1
Radio receiver assembly B5±FR speaker 2

FL: Radio receiver assembly B2±FL speaker 1
Radio receiver assembly B6±FL speaker 2

RR: Radio receiver assembly B3±RR speaker 1
Radio receiver assembly B4±RR speaker 2

RL: Radio receiver assembly B8±RL speaker 1
Radio receiver assembly BP±RL speaker 2
Is there continuity between the following terminals
with connector disconnected?

FR: Radio receiver assembly B1±ground
Radio receiver assembly B5±ground

FL: Radio receiver assembly B2±ground
Radio receiver assembly B6±ground

RR: Radio receiver assembly B3±ground
Radio receiver assembly B4±ground

RL: Radio receiver assembly B8±ground
Radio receiver assembly 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 tape player operating normally?
Wire harness faulty.
Temporarily install another speaker.
Functions OK?
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
amplifier A7

RL: Radio receiver assembly A14±Power
amplifier 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 Wire harness faulty.
only for vehicles with cellular phone
B. with CD player type BE±226
±
BODY ELECTRICAL SYSTEM AUDIO SYSTEM
WhereEverybodyKnowsYourName

5RadioVOLUME FAINT (EXCEPT WOOFER)
A. without CD player type
*Is there continuity between the following terminals
with connector disconnected?

Radio receiver assembly D3±ground
Is tape player operating normally? Radio receiver assembly faulty.
Power switch faulty.
Wire harness faulty.
Radio receiver assembly faulty.
When the volume switch is turned from minimum
to maximum, does resistance between terminals
B1±B3 of radio receiver assembly change from 0
to 50 k
?
B. with CD player type
*Is there continuity between the following terminals
with connector disconnected?

Radio receiver assembly D3±ground
Is tape player operating normally? Radio receiver assembly faulty.
Power switch faulty.
Wire harness faulty.
Radio receiver assembly faulty. When the volume switch is turned from minimum
to maximum, does resistance between terminals
B1±B3 of radio receiver assembly change from 0
to 50 k
?
Power amplifier faulty.
Temporarily install another power amplifier
Function is OK?
BE±228±
BODY ELECTRICAL SYSTEM AUDIO SYSTEM
WhereEverybodyKnowsYourName

6RadioWOOFER DOES NOT WORK
A. without CD player type
Is there battery voltage between the following termi-
nals with connector connected?

Woofer amplifier 3 ± ground

Woofer amplifier 4 ± ground
Is there continuity between the following terminals
with connector disconnected?

Woofer amplifier 9 ± Woofer 2

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

Woofer amplifier 9 ± ground

Woofer amplifier 10 ± ground Is there continuity between the following termi-
nals with connector connected?


Radio receiver assembly A9±Woofer amplifier 6
Wire harness faulty.
Wire harness faulty. Wire harness faulty.
Wire harness faulty. Woofer faulty.
Is there continuity between the following termi-
nals with connector disconnected?


Woofer amplifier 7±ground
Is there battery positive between the following
terminals with connector connected?


Woofer amplifier 7±ground
Temporarily install another woofer.
Functions OK?
Radio receiver assembv faulty. Radio receiver assembly faulty.
Is tape player operating normally?
Radio receiver
assembly faulty.Wire harness faulty.
±
BODY ELECTRICAL SYSTEM AUDIO SYSTEMBE±229
WhereEverybodyKnowsYourName

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


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

Woofer amplifier 9 (Power amplifier C9) ±Woofer 2

Woofer amplifier10 (Power amplifier C10) ±Woofer 1Is there continuity between the following terminals
with connector disconnected?


Woofer amplifier 7 (Power amplifier C7) ±ground
Is there continuity between the following terminals
with connector disconnected?

Woofer amplifier 9 (Power amplifier C9) ±ground

Woofer amplifier10 (Power amplifier C10) ±ground
Is there battery positive between the following
terminals with connector connected?


Woofer amplifier 3 (Power amplifier C3) ±ground

Woofer amplifier4 (Power amplifier C4) ±ground
BE±230±
BODY ELECTRICAL SYSTEM AUDIO SYSTEM
WhereEverybodyKnowsYourName