1991 LEXUS SC300 phone

Is there continuity between the following terminals
with connector disconnected?

Fr: Radio receiver assembly B1±FR speaker 1
Radio receiver assembly B5±FR speaker 2

FL: Radio receiver assembly B2±FL speaker 1
Radio receiver assembly B6±FL speaker 2

RR: Radio receiver assembly B3±RR speaker 1
Radio receiver assembly B4±RR speaker 2

RL: Radio receiver assembly B8±RL speaker 1
Radio receiver assembly BP±RL speaker 2
Is there continuity between the following terminals
with connector disconnected?

FR: Radio receiver assembly B1±ground
Radio receiver assembly B5±ground

FL: Radio receiver assembly B2±ground
Radio receiver assembly B6±ground

RR: Radio receiver assembly B3±ground
Radio receiver assembly B4±ground

RL: Radio receiver assembly B8±ground
Radio receiver assembly 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 tape player operating normally?
Wire harness faulty.
Temporarily install another speaker.
Functions OK?
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
amplifier A7

RL: Radio receiver assembly A14±Power
amplifier 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 Wire harness faulty.
only for vehicles with cellular phone
B. with CD player type BE±226
±
BODY ELECTRICAL SYSTEM AUDIO SYSTEM
WhereEverybodyKnowsYourName

206
CELLULAR MOBILE TELEPHONE
21C6
A
A
A AB
BS1
4
Bc1
4Bc2 8Bc115 Bc2 7Bc1 6
AA
Bc1
18 B
8
2 2
PWR
PWR 11
R L±R L±R R±W
A
B
A
TAF+ RAF+ D1 6
8
7 3
8
7
2
5 D1
RAF±
RAF+
TA F±
TAF+
PH±
PH+
GND 5
16
4
24
6
1
14
15
17
3
11 16 2727 3 910
15A
TEL
15A
ECU±IG
FROM POWER SOURCE SYSTEM
(
SEE PAGE 56 )
B±RW±L
R R
G±B
IG
+B
GR±W
BRG G
B B
W
(
SHIELDED )
W±B
( SHIELDED )
W
( SHIELDED )
R±L
L±O
R±L
(
SHIELDED )
W
(
SHIELDED )
(
SHIELDED )
W±B
BR W
L±O
BR
V
G
TELEPHONE TRANSCEIVER AND SPEAKER RELAY
TELEPHONE
MICROPHONE
[COMB. SW] MOBILEPHONE M1
C16 T16 ,
T17
AB
MIC+ GND
W
EB BT1
20 BT1 19 TELEPHONE TRANSCEIVER
BS1
8
W±L
6 1
B35B8
I3 I8:USA
I26 : CANADA B36 B34 B35
BR BR BR
B36 B34 B35BR
BR
BR±W
BR±W
BR±W
BR±W
WhereEverybodyKnowsYourName

207
Bc1
17 Bc1 5Bc116 Bc1 19 Bc 1 20 Bc24Bc23
BBA BAA B
B
BCC
12 18 23 10 5 3 9
4
10
451 1
6
5 22 25 19 6 2 1
D3 GND3 GND2 MUTE RLI+ RLI± RLO+
RLO±
D3 GND2 GND1 TEL+ TEL± SP±CUT
GND AUD+ AUD± SP+
SP±
188 4512 5
12
415
Y±B
L
B
W±B B±R B±YL±B
V
LG
LL LG
V
L
LG
V
B±R B±Y
L±B
B
Y
O
B B BR
R±B BR
R±B
TLMT FR+ FR±
MOBILEPHONE RADIO AND PLAYER
TELEPHONE TRANSCEIVER AND SPEAKER RELAY T16
,T17
M1 R4,
R5 ,R
6
A
B
B
D2 3 4
D2
11
6
R
L±Y
L±Y
Y
G±WR±W
L±W
B±W
SPEAKER RELAY
L
BV1
10 BV2 2BV21
(
W/O CD PLAYER )
(
W/O CD PLAYER )
( W/ CD PLAYER )
( W/ CD PLAYER )
15
STEREO POWER
AMPLIFIER
LG L
FR+ FR±
S14
1
2
IP1
10
IP1 1 BT1
5
BT1 6
L
LG
LG L LG
L
FRONT DOOR
SPEAKER RH
F1 2
TELEPHONE TRANSCEIVER
A
3
(
W/ CD PLAYER )
(
W/O CD PLAYER )
A
BC
WhereEverybodyKnowsYourName

208
CELLULAR MOBILE TELEPHONE
T16 (A) TELEPHONE TRANSCEIVER AND SPEAKER RELAY
(A) 9±GROUND : ALWAYS APPROX. 12 VOLTS
(A) 10±GROUND : APPROX. 12 VOLTS WITH IGNITION SW AT ACC OR ON POSITION
(A) 11±GROUND : ALWAYS CONTINUITY
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
C1628R 4A29 (W/ CD PLAYER)S1431
F1230R 5B29 (W/O CD PLAYER)T16A31
M 131R 6C29 (W/O CD PLAYER)T17B31
: RELAY BLOCKS
CODESEE PAGERELAY BLOCKS (RELAY BLOCK LOCATION)
219ENGINE COMPARTMENT LEFT
: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR
CODESEE PAGEJUNCTION BLOCK AND WIRE HARNESS (CONNECTOR LOCATION)
1C20FLOOR WIRE
: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS
CODESEE PAGEJOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)
IP138FRONT DOOR RH WIRE AND COWL WIRE (RIGHT KICK PANEL)
BS140ENGINE ROOM MAIN WIRE AND FLOOR WIRE (LEFT KICK PANEL)
BT140FLOOR WIRE AND COWL WIRE (LEFT KICK PANEL)
BV140FLOOR NO 3 WIRE AND CONSOLE BOX WIRE (UNDER THE INSTRUMENT PANEL CENTER)BV240FLOOR NO. 3 WIRE AND CONSOLE BOX WIRE (UNDER THE INSTRUMENT PANEL CENTER)
Bc140FLOOR NO 3 WIRE AND COWL WIRE (UNDER THE LEFT SIDE OF REAR SEAT CUSHIONBc240FLOOR NO. 3 WIRE AND COWL WIRE (UNDER THE LEFT SIDE OF REAR SEAT CUSHION
: GROUND POINTS
CODESEE PAGEGROUND POINTS LOCATION
EB34FRONT SIDE OF LEFT FENDER
: SPLICE POINTS
CODESEE PAGEWIRE HARNESS WITH SPLICE POINTSCODESEE PAGEWIRE HARNESS WITH SPLICE POINTS
I 338COWL WIREB3440FLOOR MAIN WIREI 838COWL WIREB3540FLOOR MAIN WIRE
I 2638ENGINE ROOM MAIN WIREB3640FLOOR NO. 3 WIRE
B 840FLOOR MAIN WIRE
SERVICE HINTS
WhereEverybodyKnowsYourName

31
Position of Parts in Body
M 1 Mobilephone R 16 Remote Control Mirror LH
M 2 Moon Roof Control Relay R 17 Remote Control Mirror RH
M 3 Moon Roof Control SW R 18 Remote Control Mirror SW
M 4 Moon Roof Motor and Limit SWS 13 Stereo Power Amplifier
O 8 Oxygen Sensor Sub (for California) S 14 Stereo Power Amplifier
P 4 Power Window Control SW RH T 16 Telephone Transceiver and Speaker Relay
P 5 Power Window Master SW and Door Lock Control SW LH T 17 Telephone Transceiver and Speaker Relay
P 6 Power Window Motor LH T 18 Tension Reducer Solenoid LH
P 7 Power Window Motor RH T 19 Tension Reducer Solenoid RH
P 20 Personal Light V 5 Vanity Light LH
R 10 Rear Combination Light LH V 6 Vanity Light RH
R 11 Rear Combination Light RH
R 12 Rear Speaker LH W 8 Wireless Door Lock ECU
R 13 Rear Speaker RH W 9 Woofer Speaker
R 14 Rear Window Defogger (+) W 10 Woofer Speaker Amplifier
R 15 Rear Window Defogger (±)
WhereEverybodyKnowsYourName

236
GROUND POINT
FRONT TURN SIGNAL
LIGHT LH
ENGINE HOOD
COURTESY SW
TRACTION PUMP AND
MOTOR
HEATER RELAY
ABS ACTUATOR RELAY
TELEPHONE
TRANSCEIVER
AND SPEAKER RELAY
ENGINE OIL LEVEL
WARNING SW
COMBINATION METER
(E1 )
EFI ECU
TRACTION ECU
CHECK CONNECTOR
(
E1 ) CORNERING LIGHT LH
FRONT SIDE MAKER
LIGHT LH
BRAKE FLUID LEVEL
SW
FRONT CLEARANCE
LIGHT LH
FRONT SIDE MAKER
LIGHT RH
FRONT CLEARANCE
LIGHT RH
ABS ACTUATOR
FRONT TURN SIGNAL
LIGHT RH
CRUISE CONTROL
ACTUATOR
OXYGEN SENSOR SUB
(
FOR USA SPEC. )
TDCL (
E1 )
WASHER LEVEL SW EFI MAIN RELAY
CORNERING LIGHT RH
A/C PRESSURE SW
(HI GH PRESSURE )
AIR FLOW METER POWER STERRI NG
PRESSURE SW
NOISE FI LTER
(
FOR IGNI TION SYSTEM ) E4
E10
E12 2
2
BS1 4 E4
E7
E1 E5
EB EA I23
I33
E1 6
I32
E20
E20
E20
IK2 24
ED EC IK1
1 BY1
5
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W± B W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B BR
BR
W±B BR
BR
BR
W±B BR
BR±B BR BR
BR
BR
W± B
W± B
W± B
W± B
W± B
W± B
W± B
W±B
W±B
BR
BR
BR
BR BR
BR
BR
W±B
BR BR
BR
( EO1 )
( E11 )
( E1 )
( EO2 )
I27BR
(
S1 )
( E1 )
NOISE FILTER (
FOR
IGNITION SYSTEM )W±B
W/ TRACTION SYSTEM
NOI SE FILTER
(
FOR DEFOGGER SYSTEM )
W±B
W±B
WhereEverybodyKnowsYourName

OVERALL ELECTRICAL WIRING DIAGRAM
1234
18 LEXUS SC300
1J
7 2
3 1J
5
1B
4 2
4 1C
6
4
ACC
IG1
ST1
AM1 2
4
7 9A 10A
8BS1
10 19 22 25 23 18 12 11 24 6 1 394 105
416 5
612
4B 5A 12A 5B 12B 8A 8B 1B 6B 2B 7B 2A 7A
6 20 Bc1 4 Bc2 3 Bc2 19 Bc1 16 Bc1 5 Bc1 17 Bc1 6 Bc1 15 Bc1 7 Bc2 4 Bc1 8 Bc2
10 IP1 1 I P15BT1 6BT1 11 A
6A
1A
11 B
19 BT1
20 BT1
18 Bc1 4 BS1 81514317
EB
16543 8 7 2
52
3A
W± L W± L W
B±Y
B±R W
W
W± L
R
Y± B
B
Y
O R
BR
GR±W
G
R± W G
W
B
B
W±B
W± B W
BR
W
L±R W
W
L±R R±L
R±L L±O
L±Y
L±B
B±Y B±R L
LG
L
LG V
V
LG L
LG
L
B±R B± YL±B
L±Y
L±O L
R±B BR
G± W
R±W
L±W
B±W
LG
L
15A
ECU± I G
15A
TEL
40A
IGSW
G±B
R
60A MAIN 100A AM1
120A ALT
BATTERY
F9
FUSE BLOCK
From Radio and Player
(
w/ CD Player )
< 19±1>
Fr om Stereo Power
Amplifier
( w/o CD Player )
< 20±1>
To Radio and Player
< 19±1> < 20±3>
F12
FRONT DOOR
SPEAKER RH MIC+ GND
M1
MOBILE PHONE
TEL EP HONE TRA NS CE I VE R
C1 6
TELEPHONE
MICROPHONE
[COMB. SW]
TELEPHONE TRANSCEI VER AND SPEAKER RELAY
SPEAKER RELAY B
Power
Source Cellular Mobile Telephone
(
SHI ELDED )
(
SHIELDED )
(SHI ELDED )
(
SHIELDED )
(SHI ELDED )
(
SHIELDED )W
I15
IGNITION SW
T16 A , T17 B 2
3
5
7
8
9
10
12 4
11 1
6 5
4
3
2
1
6789101112
AB
TELEPHONE TRANSCEIVER AND SPEAKER RELAY
T16 T17
12 Fr ont s ide of
left fender
10
9
BR BR BR
BR±W BR±W BR±W
BR BR
BR±W
WhereEverybodyKnowsYourName

1234
19 LEXUS SC300
4ACC
IG1
ST1
AM1 3
2
3BV1
2 BV2 1 BV2 6 IQ2 7 I Q2 4 BV2 3 BV2 10 BV2 9 BV2 6 BV1 5 BV1 4 BV1
10 I F2 1 IF22IG2 1IG2 11Bc2 12Bc2
10 BV1
11 IQ2 3 IQ1
7 BV2 2 BV1 19 BV1 7 BV1 18 BV1
3IG2
1Bc2
10 Bc 1
9Bc1
8Bc1
23 Bc1
8 BV2
12 IQ2 24 Bc 1
II BM 1J
5
1J
8
2
1C
6
1E
10
2
1B
4 1J
7
AMP E
MU TE A MP RU ± RU +
7A
10 C
4C
8A
3A
4A
3D
1D
6D
2D
3C
1A
6 5A 2A 6A 1B 3B 2B 6B 1C 5C 9C 2C
74
MU TE
AMP
RU±
RU+
RL±
RL +
RR±
RR+
FL±
FL+
FR±
FR+ TLMT PWR VOL+ VOLC SGND B ACC ANT ANTA ANTB WP+ WP± ACC +B E ANTB ANTA ANT ACC B IG
6
3
8
5
2
1
7
3
4
9
10
26 5 1 47
B
W
P±L
R± B BR
R± B P±L
W B Y B
W R
V
V
V
R
W B
Y
B
W
P±L
BR
BR P± L
W± B Y± R
L±W
P±G GR
L±Y
B±R
R±W
B±W
GR
L±Y
BR
L±Y
GR L±Y
GR
P± G
L±W Y±R L±Y
G±RL±YGR
P± G
L±W Y±R
Y±R
L±WP±G GR
L±Y L±Y W
P±L
VV
G±RR±L
R± W G± Y W
W± L W
LG L
P
P
P
P
V LG
L W
BR
BR
B±Y
P±L
B±Y
E
1 11 2
2 22 1
60A MAIN
100A AM1
120A ALT
40A
IGSW I15
IGNITION SW
BATTERY 20A
RADIO No. 1
7. 5A
RA DI O No. 2
RADIO AND PLAYER
F9
FUSE BLOCK A3 2
AUTO ANTENNA MOT OR AND REL AY
W1 0
WOOF ER SPEAKER
AMPLIFIER
W9
WOOFER
SPEAKER
R12
REAR
SPEAKER LH
R13
REAR
SPEAKER RH
F1 0
FRONT DOOR
SPEAKER LH
15A
ECU±I G
To Telephone Tr ans ceiv er
and Speaker Relay
< 18±7>
To A/ C Cont rol Sw
and Radio Sw
< 22±4>
To A/ C Cont rol Sw
and Radio Sw
< 22±4>
To Telephone Transc eiver
and Speak er Relay
< 18±7>
Power
Source
Radio and Player
(
w/ o CD Player )
Auto Antenna
2IE1L±Y
( SHI ELDED )
P± L (
SHI EL DED )
R2 ,R3 ,R5 , R6
CDA B 12
5
34
678910 12
3456
12 34
5678910 12
3456
CD A B
R2 R3 R5 R6 RADIO AND PLAYER
L±Y
GR
3
4
Under the
as htr ay RHBack panel
center
8
7
BR
Y B
WhereEverybodyKnowsYourName