LEXUS SC400 1991 Service Repair Manual

Wiring and Connector Diagrams
±
BODY ELECTRICAL SYSTEM Audio SystemBE±205
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Parts Inspection
(Power Switch)
REMOVAL AND INSTALLATION OF
POWER SWITCH
1. REMOVAL CONTROL PANEL(a) Remove the console upper panel.(See BO section)
(b) Remove three screws and the control panel.
2. INSTALL CONTROL PANEL For installation, follow the removal procedure in reverse.
INSPECTION OF POWER SWITCH
INSPECT POWER SWITCH
(Continuity)
Inspect continuity between terminals.
Terminal
Switch position
OFF (Power switch released) ON (Power switch pushed in)
If continuity is not as specified, replace the control panel.
(Resistance)
Inspect resistance between terminals.
Tester connectionConditionSpecified value
11±13ConstantApprox. 50 k 
11±14Switch knob
A
BApprox. 0
50 k 
If resistance is not as specified, replace the control panel.
(Illumination)
Connect the positive (+) lead from the battery to terminal 2
and the negative (±) lead to terminal 1, check that the illu-
mination light lights up.
If the illumination light does not light up, replace the control
panel.
BE±206
±
BODY ELECTRICAL SYSTEM Audio System
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(Circuit)
Disconnect the control panel connector and inspect the con-
nector on wire harness side as shown.
Check forTester connectionConditionSpecified value
Voltage2±GroundLight control switch positionTAIL or HEADBattery voltage
OFFNo voltage
If circuit is not as specified, refer to BE±199, 201, 203 wiring
diagrams and inspect the circuits connected to other parts.
(Radio Receiver Assembly)
REMOVAL AND INSTALLATION OF
RADIO RECEIVER ASSEMBLY
(See page BE±112)
INSPECTION OF RADIO RECEIVER
ASSEMBLY
INSPECT RADIO RECEIVER ASSEMBLY
(Circuit)
Disconnect the connectors from the radio receiver assembly.
And inspect the connector on the wire harness side as
shown.
(without CD player)
Check forTester connectionConditionSpecified value
ContinuityA7±GroundConstantContinuity
VoltageA4±GroundConstantBattery voltage
VoltageA3±GroundIgnition switch positionACC or ONBattery voltageg
LOCKNo voltage
A10±GroundLight control switch positionTAIL or HEADBattery voltageg
OFFNo voltage
If circuit is not as specified, refer to BE±199 wiring diagrams
and inspect the circuits connected to other parts.
±
BODY ELECTRICAL SYSTEM Audio SystemBE±207
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(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
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(Woofer)
REMOVAL AND INSTALLATION OF
WOOFER
1. REMOVE WOOFER(a) Remove woofer cover together with high mount stoplight.
(b) Remove four bolts.
(c) Disconnect connector and remove woofer.
2. INSTALL WOOFER For installation follow the removal procedure in reverse.
(Woofer Amplifier)
REMOVAL AND INSTALLATION OF
WOOFER AMPLIFIER
(without CD player)
1. REMOVE WOOFER AMPLIFIER(a) Remove the RH side cover.
(b) Disconnect the connector and remove three nuts and
the woofer amplifier with the bracket.
(c) Remove four bolts and the woofer amplifier.
2. INSTALL WOOFER AMPLIFIER
For installation, follow the removal procedure in reverse.
(with CD player±Pioneer)
1. REMOVE WOOFER AMPLIFIER (a) Remove the package tray trim.
HINT: (See page BO±124)
(b) Remove four bolts.
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BODY ELECTRICAL SYSTEM Audio SystemBE±209
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(c) Disconnect the connector and remove the wooferamplifier.
2. INSTALL WOOFER AMPLIFIER For installation, follow the removal procedure in reverse.
INSPECTION OF WOOFER AMPLIFIER
INSPECT WOOFER AMPLIFIER
(Circuit)
Disconnect the connector from woofer amplifier and inspect
the connector on the wire harness side as shown.
Check forTester connectionConditionSpecified value
Continuity7±GroundConstantContinuity
Voltage3±GroundConstantBattery voltage
4±GroundIgnition switch positionACC or ONBattery voltage
6±Ground
g
LOCKNo voltage
If circuit is not as specified, refer to BE±201 wiring diagrams
and inspect the circuits connected to other parts.
(Power Amplifier)
REMOVAL AND INSTALLATION OF
POWER AMPLIFIER
(Pioneer)
1. REMOVE POWER AMPLIFIER (a) Remove the RH side cover.
(b) Remove the CD auto changer (See page BE±212).
(c) Disconnect two connectors and remove three nuts and the power amplifier with the bracket.
(d) Remove four bolts and the power amplifier.
2. INSTALL POWER AMPLIFIER For installation, follow the removal procedure in reverse.
BE±210
±
BODY ELECTRICAL SYSTEM Audio System
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(Nakamichi)
1. REMOVE POWER AMPLIFIER
(a) Remove the RH side cover.
(b) Remove the CD auto changer (See page BE±212).
(c) Disconnect three connectors and remove three nuts and the power amplifier with the bracket.
(d) Remove four bolts and the power amplifier.
2. INSTALL WOOFER AMPLIFIER For installation follow the removal procedure in reverse.
POWER AMPLIFIER INSPECTION
INSPECT POWER AMPLIFIER
(Circuit)
Disconnect the connector from power amplifier and inspect
the connector on the wire harness side as shown.
(Produced by PIONEER)
 Check for Tester connection Condition Specified value
 Continuity B7±Ground Constant Continuity
 Voltage B10±Ground Constant Battery positive voltage
  A14±Ground
A6 G d
 Ignition switch position ACC or ON Battery positive voltage  A6±Ground  LOCK No voltage
If circuit is not as specified, refer to BE±201 wiring diagrams
and inspect the circuits connected to other parts.
±
BODY ELECTRICAL SYSTEM AUDIO SYSTEMBE±211
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(Produced by NAKAMICHI)
 Check for Tester connection Condition Specified value 

Continuity 

B7±Ground
C7±Ground 


Constant


Continuity
 

Voltage 

B10±Ground
C3±Ground 


Constant


Battery positive voltage
 


 

A6±Ground
A14±Ground 


Ignition switchposition
 


ACC or ON

Battery positive voltage
 


 


C4±Ground
C6±Ground 


Ignition switch position 


LOCK

No voltage
If circuit is not as specified, refer to
BE±203 wiring diagrams
and inspect the circuits connected to other parts.
CD AUTO CHANGER
CD AUTO CHANGER REMOVAL AND
INSTALLATION
1. REMOVE CD AUTO CHANGER (a) Remove RH side cover.
(b) Disconnect two connectors.
(c) Remove three bolts, one nut and the CD auto changer.
CD AUTO CHANGER INSPECTION
INSPECT CD AUTO CHANGER(Circuit)
Disconnect connectors from CD auto changer and inspect
the connector on the wire harness side as shown.
BE±212
±
BODY ELECTRICAL SYSTEM AUDIO SYSTEM
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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)
±
BODY ELECTRICAL SYSTEM AUDIO SYSTEMBE±213
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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