Lexus SC300 / Lexus SC400. Manual - part 160

22

CD player

DISPLAY 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.

–

BODY ELECTRICAL SYSTEM

AUDIO SYSTEM

BE–251

23

CD player

ANY 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

BE–252

–

BODY ELECTRICAL SYSTEM

AUDIO SYSTEM

Temporarily install another power amplifier.
Function is OK?

Radio receiver assembly faulty.

Power amplifier faulty.

24

CD player

VOLUME 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?

–

BODY ELECTRICAL SYSTEM

AUDIO SYSTEM

BE–253

25

CD player

RH 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

–

BODY ELECTRICAL SYSTEM

AUDIO SYSTEM