Lexus SC300 / Lexus SC400. Manual - part 159

18

Tape player

SOUND 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?

–

BODY ELECTRICAL SYSTEM

AUDIO SYSTEM

BE–247

19

Tape player

VOLUME 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



?

BE–248

–

BODY ELECTRICAL SYSTEM

AUDIO SYSTEM

20

CD player

MAGAZINE 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.

–

BODY ELECTRICAL SYSTEM

AUDIO SYSTEM

BE–249

21

CD player

MAGAZINE IS INSERTED, BUT DISPLAY DOES
NOT INDICATE ”CD”

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

BE–250

–

BODY ELECTRICAL SYSTEM

AUDIO SYSTEM