1991 LEXUS SC300 radio

(With CD player)
Check forTester connectionConditionSpecified value
VoltageA4±GroundConstantBattery voltage
A3±GroundIgnition switch positionACC or ONBattery voltageg
LOCKNo voltage
A2±GroundLight control switchTAIL or HEADBattery voltageg
positionOFFNo voltage
If circuit is not as specified, refer to BE±201, 203 wiring dia-
grams and inspect the circuits connected to other parts.
HINT: Check the wire harness between radio receiver assem-
bly and the CD auto changer, between radio receiver assem-
bly and power amplifier, in accordance with the wiring dia-
grams in BE±201, 203.
(Front Door Speaker)
REMOVAL AND INSTALLATION OF
FRONT DOOR SPEAKER
(See page BO±35)
(Tweeter)
REMOVAL AND INSTALLATION OF
TWEETER
(See page BO±34)
(Rear Speaker)
REMOVAL AND INSTALLATION OF
REAR SPEAKER
1. REMOVE REAR SPEAKER
(a) Remove the package tray trim.
HINT: (See page BO±124)
(b) Remove eight bolts.
(c) Disconnect connectors and remove the rear speaker.
2. INSTALL REAR SPEAKER For installation, follow the removal procedure in reverse.
BE±208
±
BODY ELECTRICAL SYSTEM Audio System
WhereEverybodyKnowsYourName

 
Check for Tester connection Condition Specified value
 Voltage A4±Ground Constant Battery positive voltage
  
A3±Ground
 Ignition switch
iti
 ACC or ON Battery positive voltage
  A3±Ground position LOCK No voltage
 Continuity 
A7±Ground
 Luggage compartment
d t it h
 Push (OFF) No continuity  A7±Ground door courtesy switch Free (ON) Continuity
If circuit is not as specified, refer to BE±201, 203 wiring dia-
grams and inspect the circuits connected to other parts.
HINT:
w Check the wire harness between the radio receiver
assembly and the CD auto changer in accordance with
the wiring diagrams in BE±201, 203.
w Since the signals to and from the CDL+, CDL, CDR+,
CDR, TXM+, TXM, TXS+ and TXS terminals are serial
signals, they cannot ordinarily be measured with a
tester.
LUGGAGE COMPARTMENT DOOR
COURTESY SWITCH
(See page BE±82)
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BODY ELECTRICAL SYSTEM AUDIO SYSTEMBE±213
WhereEverybodyKnowsYourName

MOTOR ANTENNA
MOTOR ANTENNA REMOVAL AND
INSTALLATION
1. REMOVE MOTOR ANTENNA
(a) Remove the antenna nut.
(b) Remove the LH side cover.
(c) Disconnect the motor antenna connector and the antennacord.
(d) Remove the nut and the motor antenna assembly.
2. INSTALL MOTOR ANTENNA
(a) Install the antenna nut.
(b) Connect the motor antenna connector and the antenna cord.
(c) Install the nut.
ANTENNA ROD REMOVAL AND
INSTALLATION
1. REMOVE ANTENNA ROD HINT: Perform this operation with the battery negative (±)
cable connected to the battery terminal.
(a) Turn the ignition switch to ºLOCKº position.
(b) Remove the antenna nut.
(c±1) with CD player
Press the ºAMº and ºCDº buttons on the radio receiver, and
simultaneously turn the ignition switch to ºACCº position.
(c±2) without CD player Press the ºAMº and ºT APEº buttons on the radio receiver, and
simultaneously turn the ignition switch to ºACCº position.
HINT:
w The rod will extend fully and be released from the motor
antenna.
w After removing the antenna rod, leave the ignition switch
at ºACCº.
NOTICE: To prevent body damage when the antenna rod is re-
leased, hold the rod while it comes out.
BE±214±
BODY ELECTRICAL SYSTEM AUDIO SYSTEM
WhereEverybodyKnowsYourName

2. INSTALL ANTENNA ROD
(a) Insert the cable of the rod until it reaches the bottom.HINT:
wWhen inserting the cable, the teeth on the cable must
face toward the rear of the vehicle.
w Insert the cable approx. 400 mm (15.75 in.).
(b) Wind the cable to retract the rod by turning the ignition switch
to ºLOCKº position.
HINT:
w If the ignition switch is already in ºLOCKº position,
perform step 1.
w In case the cable is not wound, twist it as shown in the
illustration.
w Even if the rod has not retracted fully, install the ant enna
nut and inspect the antenna rod operation. It will finally
retract fully.
(c) Inspect the antenna rod operation by pushing the radio wave
band select buttons.
MOTOR ANTENNA INSPECTION
1. INSPECT MOTOR ANTENNA (Circuit)
Disconnect the motor antenna connector from the body wire
harness and inspect the connector on body wire harness side
as shown.
 Check for Tester connection\
\
Condition Specified value
 Continuity 7±Ground\
\
Constant Continuity
 Voltage 3±Ground\
\
Constant Battery positive voltage
 
g
 8±Ground Ignition switch ACC or ON Battery positive voltage
  8±Ground 
g
position LOCK No voltage
  6±Ground Ignition switch ON Battery positive voltage
  6±Ground 
g
position ACC or LOCK No voltage
  2±Ground Ignition switch Radio or Tape or CD switch ON Battery positive voltage
  2±Ground 
g
ACC or ON Radio or Tape or CD switch OFF No voltage
  5±Ground Ignition switch Radio switch ON Battery positive voltage
  5±Ground 
g
ACC or ON Radio switch OFF No voltage
  
4±Ground
 Ignition switch
ACC or ON and
 AM or FM (87.9 ± 96.0 MHz) Battery positive voltage
  4±Ground ACC or ON and
radio switch ON Others No voltage
 


 

1±Ground
 

Ignition switch
ACC or ON and 

AM
 

Battery positive voltage
   radio switch ON Others No voltage
If circuit is not as specified, inspect radio or wire harness. If
circuit is as specified, replace motor antenna.
±
BODY ELECTRICAL SYSTEM AUDIO SYSTEMBE±215
WhereEverybodyKnowsYourName

TROUBLESHOOTING
NOTICE: When replacing the internal mechanism (ECU part) of the audio system,\
be careful that no part
of your body or clothing comes in contact with the terminals of the lead\
s from the IC, etc. of the replace-
ment part (spare part).
HINT:
This inspection procedure is simple troubleshooting which should be carried \
out on the vehicle during
system operation and is based on the assumption that the cause of trouble lies\
with the system
components (excluding the wires and connectors, etc.).
Always inspect the trouble taking the following items into consideration\
.
Open or short circuit of the wire harness

Connector or terminal connection fault

The cassette tape or compact disc itself may be causing the trouble, so whe\
n troubleshooting the tape
player or CD player, always use a different cassette tape or compact disc first of all to check operation
of the tape player or CD player.

For some of problems in the following problem chart, the AUDIO SYSTEM CHECKER can be used
to inspect malfunctions of the Radio or Tape Player, and the CD PLAYER CHECKER can be used to
inspect the CD player.
The portions indicated by on the flow charts on the following pages can be\
inspected using a CHECK-
ER.
For instructions on how to connect the checker to the vehicle and how to\
use the checker, please refer
to the instruction Manual for AUDIO SYSTEM CHECKER or CD PLAYER CHECKER.
BE±218
±
BODY ELECTRICAL SYSTEM AUDIO SYSTEM
WhereEverybodyKnowsYourName

 
\
 \

Problem No.
 \
 \
Radio not operating when power switch turned to ºONº 1
 


\
 
\

\

Display indicates when power switch turned to ºONº, but no sound (\
including ºnoiseº)
is produced (except woofer). 


2
 \
 \
Noise present, but AM±FM not operating 3
 
Radio
\
 \
Any speaker does not work (except woofer). 4
 Radio\
 \
Volume faint (except woofer). 5 \
 \
Woofer does not work. 6 


\
 
\

\
Woofer volume faint. 

7
 \
 \
Reception poor. 8
 \
 \
Preset memory disappears. 9
 \
 \
Volume remains at maximum level. 10
 \
 \
Cassette tape cannot be inserted. 11
 \
 \
Cassette tape will not eject. 12
 \
 \
Display indicates, but no sound is produced (except woofer). 13 \
 \
Any speaker does not work (except woofer). 14 

Tape player
\
 
\

\
Volume faint (except woofer). 

15
 \
 \
Woofer does not work. 16
 \
 \
Woofer volume faint. 17
 \
 \
Sound quality poor. 18
 \
 \
Volume remains at maximum level. 19
 \
 \
Magazine cannot be inserted into auto changer. 20
 \
 \
Magazine is inserted, but display does not indicate ºCDº. 21 \
 \
Display indicates, but no sound is produced (except woofer). 22 


\
 
\

\
Any speaker does not work (except woofer). 

23
 CDplayer\
 \
Volume faint (except woofer). 24
 CD player\
 \
RH channel or LH channel speaker volume faint. 25
 \
 \
Woofer does not work. 26
 \
 \
Woofer volume faint. 27
 \
 \
Sound quality poor. 28
 \
 \
Volume remains at maximum level. 29 
Noise
\
 \
Noise produced by vibration or shock while driving. 30 


Noise\
 
\

\
Noise produced when engine starts. 

31
 Antenna\
 \
Antenna±related. 32
±
BODY ELECTRICAL SYSTEM AUDIO SYSTEMBE±219
WhereEverybodyKnowsYourName

1RadioRADIO NOT OPERATING WHEN POWER
SWITCH TURNED TO ºONº.
A. Without CD player type
Does radio operate normally when AM or FM
button is pushed?
Check if RADIO NO.1 and RADIO NO.2 fuses
are OK.Is there battery voltage between the following
terminals with connector connected?

Radio receiver assembly A3±ground

Radio receiver assembly A4±ground
Is there continuity between the following termi-
nals with connector disconnected?

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


Radio receiver assembly B2±power switch 12

Radio receiver assembly B4±power switch 11
Wire Harness faulty.
Is there battery voltage between the following
terminals with connector connected?


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

Power amplifier B7±ground
Power amplifier faulty.
BE±220±
BODY ELECTRICAL SYSTEM AUDIO SYSTEM
WhereEverybodyKnowsYourName

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