LEXUS SC400 1991 Service Repair Manual

OVERALL ELECTRICAL WIRING DIAGRAM
1234
20 LEXUS SC300 (
Cont . ne xt pa ge )
4 ACC
IG1
ST1
AM1 3
2
1J
7
1B
4
5
BV3 4
BV3 15
BV3 14
BV3 13
BV3 12
BV3 1
BV3 8
BV3 11
BV3 10
BV3 3
BV3 2
BV3 16
BV3 10
BV1 11
IQ2 2
IE1
3
IG2 2
2
74 3F 8F 9F 10F 1F 6F 11F 2F 7F 4F 5F 12F 3E 2C 6C 1C 3C 4D
6 1G 3G 2G 6G 1H 5H 8H 2H 6H 9H 4H 3H
3
IQ1 7
BV2
2
BV1 1
BV1 19
BV1 7
BV1 18
BV1
1J
8
1E
10
7D 6D 15D 14D 5D 13D 12D 11D 1E 5E 1D 2E 8D 4E 10E
3D
13
BV1
12
BV1
16
BV1
15
BV1
11
BV1
14
BV1
8
BV1
17
BV1
6
BV1
5
BV1
4
BV1
9
BV1
3
BV1
7H
B± Y
GR
L±Y
L±W B±RL±G
Y±R
R±B L±B
P± L W
BR B
G Y
W
BR L
R
L±YW
P±L
B± Y
W
W± L
W
G±WG± OY±R Y± L
B
W
BR
L
R
Y±B
V±W G±B
V
L±Y L±Y W
P±L
L±Y
L±Y
GR
L±Y
L±Y
P± G
L±W
Y±R GR
GR
L±Y
L±W B± R
L±G
Y± R
G±Y
R±W R± L
G± R V
G± B
V±W Y± B R
L
BR W
B
Y± L
Y±R
G± O
G±W
R L
BR
WY
G
BR±B BR
B
W
P±L
R± B
P±L
W
B
BR G
Y
W
BR
L
R
L±B R± B
GR
To Luggage Compar tment
light SW< 6±3>
From Telephon Tr ans ceiv er
and Speaker Relay< 18±1>
To A/C Control SW and Radio SW
< 22±4>
From A/C Control SW and Radio SW
< 22±4>
40A
IGSW I15
IGNITION SW
R± W
TXM+ TXM± TXS+ TXS± CDR+ CDR± SGND CDL+ CDL± GND +B ACC SW
TXM+ TXM± TXS+ TXS± CDR+ CDR± SGND CDL+ CDL± GND +B
BATTERY
60A MAIN 100A AM1
120A ALTF9
FUSE BLOCK F¥
RF¥ LR¥RR¥ L MUTE B E EP GND S GND RU+ RU± A MP MUTE
ACC TLMT PWR VOL+ VOLC SGN1 B ACC ANT ANTA ANTB
P±L
7 . 5A RA DI O No. 220A RADIO No. 1
CD PL AYER
CD A UTOMAT I C CHA NGE R
RA DI O A ND P LA YE R
Power
SourceRadio and Player
(
w/ CD Player )
(
SHI ELDED )
(
SHIELDED )
( SHIELDED )(
SHI ELDED)
( SHI EL DED )
( SHI EL DED )
(
PIONEER )
( PIONEER )
7 8
(
SHI EL DED )
C9 R2 , R3 , R4
F DCE
12
3456
12 34
5678910
GH
CD AUTOMATIC CHANGER
C2 0 C2 1
C20 , C21 GH
123 45
6789101112 F
CD PLAYER
C9 123 45
6 7 8 9 10 11 12
12
3456D
E
RADIO AND PLAYER
R2
R4 R3 C(
PI ONEER )
3
4
1234 567
8 9 10 11 12 13 14 15
BR BR
BR
BR
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567 8
20 LEXUS SC300(
Cont ' d )
2
MUTE
5 RU±1
RU+
9
WF±
10WF+
6
AMP 8
GN D 3
B 4
ACC 7
E 6 BV2 5 BV2 2 IG2 1 IG2
11 BC2 12 BC2
10 IF2 1 IF2
6 IQ2 7 IQ2
1B FR+ 2B
FL +
5B
FR± 6B
FL ± 3B
RR+ 4B
RR± 8B
RL+ 9B
RL ±
6A AMP
11 ASGND
10 AGND
9ABEEP
3AMU TE
8AR¥
L
7AR¥
R
2AR¥
L
1AF¥
R
7AE
2
12 121
2
1
8 BV2
12 IQ2 II 23 Bc1 9 Bc1
8Bc1 1Bc2 10Bc1 1J
5
1C
6
4
AMP
7E
1
ANTB 2
ANTA 5
ANT3
B 8
ACC 6
IG
24 Bc 1
BM
B±Y
GR
L±Y
L±W B± R
L±G
Y± R
R± BL±B
P±L WB
BR
GY
W
BR L
R L±Y
R± B P± L P± L
BR
BR
P
V
P
V
P
V
P
V
LG
L
P
V
B Y
Y±R
L±W
P± G L±Y GR
B±RGR
L±Y
B±R L±G
Y±R
Y B
W R
P±L
P±L
W± B
BR
BR BR BR
R
L
BR W
Y
G
BR
P±L GR
L±Y
L±W L±B P±L
L±YGR GR
B± Y
To Telephon
Transceiver
and Relay< 18±1>
15A
ECU± I G
W
B
B±W
R± W
W9
WOOFER
SPEAKER
W10 WOOFER SPEAKER
AMPLIFIER STEREO POWER AMPLIFIERR12
REAR
SPEAKER LH
R13
REAR
SPEAKER RH
F10
FRONT DOOR
SPEAKER LH
A32
AUTO ANTENNA MOTOR AND RELAY
Radio and Player(
w/ CD Player )
Auto Antenna
(SHI ELDED )
( SHI ELDED ) (
SHIELDED )
(
PIONEER )
( PIONEER )
P± L
(NAKAMICHI )
( PI ONEER )
(
PIONEER )
BR±B
S13 , S14 AB
6
4
3
2
1
7 8 9 10 11 12 14 5
13
12
5 34
678910 A
B
STEREO POWER
AMPLIFIER
S1 3
S1 4
P±L L±B
Under the
as htr ay RH Back panel c ent er
(
PIONEER )
10 B 14 AL±YGR+B ACC
L±Y
GR
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OVERALL ELECTRICAL WIRING DIAGRAM
1234
21 LEXUS SC300 (
Cont . ne xt pa ge )
4 ACC
IG1
ST 1
IG2
AM1
3
2
6
11 AM2
1J
7
1B
4 16 IE1
20 IK110 IK2
1IE1
1J
31J 51J821B 2
1E
1E
18
1E 1H1E 2 1E
131B
IG1 20 3D
3A 4
3D
2
3C
6
3A
2
3F
1 2 1 6
3F 5
3C
5
3A
IK16
IK1 7
10 IJ1
IE110
IG118
EB
19 IG1
ED EA 13 IE2 14 IG3 W± R
R
Y
B± O Y± B
V±R V± Y
R± W
L±R
W
R±Y B
V±W V
R
L±R
P± L
R
L±R L±R
P± L
P± L
Y
B±O B±YP±L
W± L
R± W
B
W± B R±W
B
W
W
W±L
W± L W±L
W
W±R
Y±B
V±R
V± Y
R±WV±Y V± R Y±B
W± R
W
W± R
B± O
R±W R± W
B
B
R±W R±W
R±W V±Y
BR
W± B
R±W Y
W±B Y
R4713
21 11
4
12
8
7
9
2
1
2
340A IGSW
100A AM1
120A ALT
60A MAIN
30A INJ
30A AM2
14
9 I15
IGNITION SW
7. 5A I GN
10A GAUGE
15A CIG
10A DOME
15A ECU±B
From ABS ECU
<9±2>
From ABS ECU
< 8±5>
(
* 1 )
(
* 2)
6
BATTERY
F9
FUSE BLOCK
12
O2
OI L P RE SS URE SW
C5
COOLANT LEUEL
WARNING SW E6
ENGI NE OI L L EVEL
WARNING SW
P3
PARKI NG
BRAKE SWD2
DIODE
(f or Par king
Brake )
B1
BRAKE FLUID
LEVEL SW
B
B
R±W R±WR±W
R±W
B
B B
( Canada )
(
Canada )
( US A )
(USA )
(
US A )
(
US A )
(
Canada )
(
Canada )(
Canada )
(
* 2
) (
* 1)
(
US A )(
US A)
(
USA )
R±W
R± W
Fro m Dayt i me
Running Light
Relay< 4±4>
Fr om Cr uise Control
ECU< 16±2> T1 5
TRIP SW AND THEFT DETERRENT
I NDI CA TOR L I GHT
S3
SPEED SENSOR No. 1
From Tr act ion ECU
<8±7>
2
W
12 12 2 54 11 13 *
1: (
w/ Tr action Contr ol )
* 2: (
w/oTractionControl )
Power
Source Combination Meter
R±WL±R
R
4 3
SECURITY
M
H
SET
RESET A/ B
W1
WASHER
LEVEL SW
P± L
L±R
R W± R
From ABS ECU
<8±5>
( * 1)
R
R
10 11 12 13 17 18 19 20 21 12345 6789
14 15 16 12 34 56 78
9 10 1112 13 14 1516 1718
17 18
1 2345 6789 10
23
22
21
20
19
15
14
13
12
11 16
AB C
C12 C13 C14 COMBINATION METER
1 1
23
DE
FUEL SENDER
F1 7 F1 8
Rear side of
c ylinder head LH Fr ont side of
right fender Fr ont s ide of
left f ender
2
1
2 2
1 1
1
B
S HORT CONNE CTOR
1
2 12F
S23
G
S22
7BU1
From Tilt and
Power Telesc opic
ECU< 11±2>
GR
B
( M/T ) 3
G±B
From Theft Det err ent and
Door Lock ECU< 17±2>
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567 8
21 LEXUS SC300(
Cont ' d )
AIR BAG
CHA RGE
OIL
OIL LEVEL COOLANT
LEVEL REAR
LI GHT
PWR
ABS TRAC
TRAC OFF
CRUISE WASHER
O/ D OFF
FUEL
SEAT BELTP
R N D 2 L
A
C
C A
A
B
B
B
C
C
C
C
C
C
C
B C
C
B
B
BA
B
A
A
C
CA A A A A A A A
C
C
C
C C C A C C B B B B
B A A C C
10 : 00
BK 1E
18 3D
10
3A
1
1J
1 1K
12
IH IF ED
IK1
8
IK2 IK1
9
1
E
3
E
2
E
1
D
BU110
BU1
3
BU1
4 11
11
1
14
19
8
18
11
13 6
18
17
16
20
19
15
13
3
15 5
1
20 9
18 8
11
87 1 2 3 4 5 16 17
2
3
4
5 10 9
12 23 12 4 17 16 7
6
15
10 22 21
W± R
RY
B±O
Y±B
V± R
V±Y
R±W
L±R
W
R± Y B
V±W V
R
L±R
P±L
Y±B
B±Y
B± W
W±B BR
B
W± B W± B BR±B
Y± G
B
Y±G
BR±B
W± B
W±B
W±B
BR±B W± B BR
Y±G
WATER
TEMP.HI GH BEAM TURN
LH
RH
BRAKE DOOR
TACHO
TRI P
SPEED
ILLUMINATIONCHECK±
ENGINE
FUEL
See Taillight and
St op Light Sy stem
<4±6><5±6>
SeeEngineControlSystem
<2±3>
Se e ABS Sy st e m< 8± 7> < 9± 3>
See Cruise Control System
< 16±3>Se e ABS an d Tr act io n
Control System< 8±7>
SeeECTandA/TIndicator
System< 3±5>
D
F1 7 , F18 E
FUEL SENDER Y±B
B±Y
B±W 24
See SRS Airbag System< 15±4>
See Charging Sy stem< 1±2>
See Headlight Sys tem< 4±1> < 5±1>
See Turn Signal and
Hazard Warning
Light Sy stem< 7±3>
See ECT System< 3±5>
From Neutr al St art SW< 1±3>
See Interier Light System< 6±3> From Igniter º TACº < 1±5>
To Engine and ECT ECU< 2±7>
To Cruise Control ECU< 16±3>
To PPS ECU< 15±2> See Illumination System
<4±7><5±7>
See ECT and A/T Indic ator
Syst em< 3±6>
See Unlock and Seat Belt
Warning Syst em< 4±4> < 5±4>
W3
WATER TEMP.
SENDER
Combination Meter
1
COMBINATION METER C12 , C13 , C14
A
AB IG1
8
Under the
c ent er
pillar LH Under the
as htr ay LH
Lef t
kick panelRear side of
c ylinder head RH
C
2
G 2
F
1
F 14
L±R
P
P
SH OR T C ON NE CT OR
S2 2 G , S23 F L±R
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OVERALL ELECTRICAL WIRING DIAGRAM
1234
22 LEXUS SC300 (
Cont . ne xt pa ge )
4 ACC
IG1
ST 1
AM1 3
2
1J
7 21J
51K2
22 22
1B
4 2
1A
5
22 222 2 1
3
5 4
53
1
2
EB1 EB1 3IN1
2IN1
IN1
6
1IN1
12 IN1
EB I J 1 2
M
2 1 2
A 1
B
2
B
M
1A IJ1
2
5 4 216
4
6 12
4
74
3
W
B
P±L
B±Y
LW±G R W
P± L
R±L
L±W
G± Y
G±R R±L
R± W
BR±W G±W BR
R±Y V
W± G BR
G± Y
Y
B±R
BR±W G± W BR
R± Y V
W± B
L
BR
G±Y
RL±R
W± B
W± B W± B
W±B
W±B B
W± L W
W W
B
L
W
I15
IGNITION SW
40A IGSW
60A MAIN
120A ALT 100A AM1
F9
FUSE BLOCK
BATTERY
To Engine and
ECT ECU< 2±7>A/ C MAGNETI C
CL UTCH REL AY
10A HEATER 60A HEATER
To Radio and Player
< 19±3> < 20±2>
From Radio and Player
<19±3><20±1>
From Radio and Player
<19±3><20±1> To Radio and Player
< 19±3> < 20±2>
5 12
L±W
R±L
COOL
WARM
Power
Source Automatic Air Conditioner
R±L
R±LR±L
B
W±B W±B
B3
BLOWER
RESISTOR
(for Low
Speed )
A2
A/C LOCK SENSOR
AND A/C MAGNETIC
CLUTCH A17 , A18
A/C POWER TRANSISTOR
AB
A27
A I R MI X CONT ROL S ERV O MOTOR
HEATER
RELAY
B2
BLOWER
MOTOR Y
B±R A/ C POWER TRANSI ST OR
L±W
L±R
W
12
12
AB
A1 7 A1 8
A/C CONTROL ASSEMBLY
1 23 45 6
7 8 9 10 11 12 14 15
13 12 34
5 6 7 8 9 10 11 12 13 14 15 16 20 21 22 23 24 25 123456 7891011
17 18 19
EC D
A12 A13 A14
Front side of
lef t fender Ri gh t ki c k
panel
1
2
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567 8
22 LEXUS SC300(
Cont ' d )
12
II1
7
II1 2 IR2
5
IR2 4
IR2
IR1
IR1
IR1
IR1
IR2
IR2
IR2
IR2 1J
82
1E
22
5
1B
3A 3A
3A
3E
3H 3G 3B
3G
11
1E
IQ1
IQ1 IQ1 IQ1 IQ1 IQ1 II1
5
IR2
IR1
IR1
IR1
IN1
4
EB1
12 IR1
13
IR1
IR1 5
IQ117
IQ1 6
IQ1 21 12 31
IQ1 16
D
D
D
D
D
D
C
D D
D
E
E
D
IR1
4
D
C
C
D
D
E
IQ1
D
E C
D
C
E
E
E
D
D D D
D D
IQ1
C E
D
IR1
IR2
5IN11E
18
1J
1
EA IF
POWER
VOLUME AUTO
BCD SW
(Room Temp.
Contr ol SW )
M
EIR1
M
W
P± L
R±L
L±W
G± Y
G± R[ R±L
R± W
BR±W G±W BR
R±Y V
W±G BR
G± Y
Y
B±R R± G
B±Y
B±R Y
G±O V±R
V±W
L±W
BR±W G±W BR
R±Y V
L±Y
G± Y Y
B±R P± L
P
GR
G±R G Y±L
Y±G L±Y
LG±R
Y± R
L
W
L±B
Y± B P±B
W± B R
L±R
R± Y B
L±R L±O
B
R± Y L±R R
W± B P±B
L±B Y±L W
L
Y±G
LG±R
L±Y
Y±R Y± L BR
BR
BR
BR
BR
BR±W
BR
BR±W
BR±W BRBR±W
Y± GBRW
Y± L
P± B
W± B
R
BR±W
G±W BR
R±Y V
W±G BR
G± Y
Y
B±R P± L
P±B
P± B
BR
GR
BR
LG
R±L
R±L
B± Y B±Y
R± L B±Y
P± L
W
L±R
L±W
BR±W BR
BR±W
BR±W
GRBR
G±R
BR L±G
L±G
W±B
W±B W±B R
L±R
BR± W
BR
L±W
BR
BR± W
11
12
13
14
351 2 2
4
5
6
7
8
9
3
4
4
2
1
6
1
1
W/ V
MGCIGN
RDFGR ACC+B
E
DI N
MDEF
LP
MFACE TC
TPM
TW
TE
ST
TR
IG+
SET5
SET4
SET3
SET2
SET1
SAUTO
HR
S5
TP
SG
MC
MH
A/ CI N
LCKIN
LV
BL R
DOUT
TAM
TPI
MR EC
MF RS
4 5
23
8
17
8 7 3 2
16
15
14
13
12
4
9
18
22
20 3
2
7 11 9
10 25 5 8
8
1
2
3
3
2
1 9 9
5
18
8 6
10 6
8 10 1 9 13
5 9 6 7 1 15 10 15
1 4 3
127
11
7
Automatic Air Conditioner
3 1 6 5
13 3 3 5
5
12
6 19 IR2
10
DEF FACE
A3
A/C PRESSURE SW
V4
VSV(
for Water Valve )
A15
A/C CONTROL
SW AND
RADIO SW
To TDCL< 2 ±4 >
A1
A/C AMBIENT
TEMP. SENSOR
A3 3
AI R INLET CONTROL
SERVO MOTOR
To Engine and ECT ECU
<2±7>
From I gniter
< 1±5>
From Defogger
Relay< 15±3>
To TDCL< 2±4>
From Rheostat < 5±7> < 6±7> A28
AIR VENT MODE
CONTROL SERVO
MOTOR
W6
WATER TEMP. SENSOR
(
for A/C System )
A16
A/C EVAPORATOR
TEMP. SENSOR
A20
A/C SOLAR SENSOR
A19
A/C ROOM TEMP. SENSOR 15A
CIG
10A
DOME
A12 , A13 , A14
ECD
A/ C CONTROL ASSEMBLY
II1 II1
1
4
BR
G±Y
7
BR
RECIRC FRESH
3H
12 IK110
To Check Connec tor
< 2±3>BR BR
P±B P±B
Fr ont side
of right
fender Lef t kic k panel
1
2
R±LN4
NOI SE FILTER C
3
E
6
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OVERALL ELECTRICAL WIRING DIAGRAM
1234
23 LEXUS SC300(
Cont ' d )
5Ba2
BK
M
21
12
7W± B W± B L
L±B
P1 7
POWER SEAT MOTOR
( for Driver' s Seat
Si de Con t ro l )FRONT
REAR
SL I DE
Under the center
pillar LH
4Ba2
L±W
L±W
FRONT VERTICALUPP1 3
POWER SEAT MOTOR
(
for Driver' s Seat
Front Ver tical Cont rol )L±Y
DOWN
L±R
M
21
56 REAR VERTI CAL
UPP15
POWER SEAT MOTOR
(
for Rear Vert ical
Control )Y±G
DOWN
Y±L
M
21
98 LUMBAR SUPPORT
RE L EA SEP1 4
POWER SEAT MOTOR
(
for Driver' s Seat
Lumbar Support Control )G±R
PUSH
G
M
21
10 12
3
4 RE CL I NI NG
FRONTP16
POWER SEAT MOTOR
(
for Reclining
Motor Cont rol )Y±R
REAR
Y±B
M
21 11
P8
POWER SEAT CONTROL SW
(
for Driver' s Seat )
1C
8
1B
2
4
6
L±W
W± L
W
30A
DOOR
BATTERY100A AM1
120A ALT
F9
FUSE BLOCK
6
5
Power Seat
(
w/o Driving Positiotn Memory )
Power Source
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242
HOW TO READ THIS SECTION
OVERALL ELECTRICAL WIRING DIAGRAM
WhereEverybodyKnowsYourName

Junction Block (the number in the circle is the
J/B No. and connector code is shown beside
it). Junction Blocks are shaded to clearly
separate them from other parts (different
junction blocks are shaded differently for fur-
ther clarification.).
Example:
Indicates related system.
Indicates the wiring harness and wiring har-
ness connector. The wiring harness with male
terminal is shown with arrows
Outside numerals are pin numbers.
is used to indicate different wiring and
connector, etc. when the vehicle model, engine
type, or specification is different.
Indicates a shielder cable.
Indicates and located on ground point.
The same code occuring on the next page
indicates that the wire harness is continuous.
System Title
Indicates the wiring color.
Wire colors are indicated by an alphabetical
code.
B = Black L = Blue R = Red
BR = Brown LG = Light Green V = Violet
G = Green O = Orange W = White
GR = Gray P = Pink Y = Yellow
The first letter indicates the basic wire color and the
second letter indicates the color of the stripe.
Indicates the connector to be connected to a
part (the numeral indicates the pin No.)
The position of the parts. is the same as shown
in the wiring diagram and wire routing.
Indicates the pin number of the connector.
The numbering system is different for female
and male connectors.
The numbering system for the overall wiring
diagram is the same as above.
Indicates a Relay Block. No Shading is used
and only the Relay Block No. is shown to distin-
guish it from the J/B.
243
WhereEverybodyKnowsYourName

244
Rear Window Defogger
and Mirror Heater
Remote Control Mirror
Seat Heater
Shift Lock
SRS AIRBAG
Starting
Taillight and
Stop Light
Theft Deterrent and
Door Lock Control
Turn Signal and Hazard
Warning Light
Wiper and Washer
Wireless Door Lock
Remote Control
Horn
Ignition
Illumination
Interior Light
Liquid Crystal Inner
Rear View Mirror
Moon Roof
Power Seat
(Driver's)
Power Source
Power Window
PPS (Progressive
Power Steering
Radio and Player
ABS and
Traction Control
Automatic
Air Conditioner
Auto Antenna
Back±Up Light
Cellular Mobile
Telephone
Charging
Cigarette Lighter
Combination Meter
Cruise Control
Headlight and Light Auto
Turn Off (for USA)
Headlight
(for Canada) ECT and
A/T Indicator
4±2 16±2 7±2
3±2 21±2 3±8
14±4
18±2 19±4 (w/o CD Player)
20±8 (w/ CD Player)9±2 8±2
4±7 (for USA)
5±7 (for Canada)11±2
12±311±5 (w/ Driving
Position Memory)11±7 12±1 1±5 13±2
6±2 15±2 14±2
13±2
17±7 7±3 17±2 15±3
1±315±2
Power Tilt and
Power Telescopic12±2
Power Seat (Passengerºs
and Electric Tension Header
5±2 2±2
Cornering Light ABS (Anti±Lock
Brake System)
22±2
Engine Control Unlock and Seat
Belt Warning
1±2
23±2 (w/o Driving
Position Memory)
1 23±119±2 (w/o CD Player
20±2 (w/ CD Player
14±310±2 (w/ Memory)
5±7 (w/o Memory)
4±3 (for USA)
5±3 (for Canada) 4±5 (for USA)
5±5 (for Canada)
OVERALL ELECTRICAL WIRING DIAGRAM
WhereEverybodyKnowsYourName