Lexus SC300 / Lexus SC400. Manual - part 158

15

Tape player

VOLUME FAINT (EXCEPT WOOFER)

A. without CD player type

Is radio operating normally?

Radio receiver assembly faulty.

When the volume switch is turned from minumum to
maximum, does resistance between terminal B1–B3
of radio receiver assembly change from 0 to 50 k



?

Power switch faulty.

Wire harness faulty.

Is there battery voltage between the following ter-
minals with connector disconnected?

 Radio receiver assembly D3 – ground

Radio receiver assembly faulty.

B. with CD player type

Is radio operating normally?

Radio receiver assembly faulty.

When the volume switch is turned from minumum to
maximum, does resistance between terminal B1–B3
of radio receiver assembly change from 0 to 50 k



?

Power switch faulty.

Wire harness faulty.

Is there battery voltage between the following ter-
minals with connector disconnected?

 Radio receiver assembly D3 – ground

Radio receiver assembly faulty.

Power amplifier faulty.

Temporarily install another power amplifier.
Function is OK?

–

BODY ELECTRICAL SYSTEM

AUDIO SYSTEM

BE–243

16

Tape player

WOOFER DOES NOT WORK

A. without CD player type

Is radio operating normally?

Radio receiver assembly faulty.

Wire harness faulty.

Is there battery voltage between the following ter-
minals with connector connected?

 Woofer amplifier 3 – ground

 Woofer amplifier 4 – ground

Is there battery voltage between the following ter-
minals with connector connected?

 Woofer amplifier 6 – ground

Is there continuity between the following termi-
nals with connector disconnected?

 Woofer amplifier 7 – ground

Wire harness faulty.

Wire harness faulty.

Woofer faulty.

Wire harness faulty.

Is there continuity between the following terminals
with connector disconnected?

 Radio receiver assembly A9 – Woofer amplifier 6

Radio receiver
assembly faulty.

Wire harness faulty.

Is there continuity between the following terminals
with connector connected?

 Woofer amplifier 9 – Woofer 2

 Woofer amplifier 10 – Woofer 1

Is there continuity between the following terminals
with connector connected?

 Woofer amplifier 9 – ground

 Woofer amplifier 10 – ground

Temporarily install another woofer.
Functions OK?

Radio receiver assembly faulty

BE–244

–

BODY ELECTRICAL SYSTEM

AUDIO SYSTEM

B. with CD player type

HINT: The part names and terminals indicated in brackets ( ) are for models 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

–

BODY ELECTRICAL SYSTEM

AUDIO SYSTEM

BE–245

17

Tape player

WOOFER 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 models 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

BE–246

–

BODY ELECTRICAL SYSTEM

AUDIO SYSTEM