1991 LEXUS SC400 stop start

OVERALL ELECTRICAL WIRING DIAGRAM
1234
16 LEXUS SC300
4ACC
IG1
ST1
IG2
AM1 2
1
11 AM2
3A
4
1J
7
1B
5 1J
5
2
1J
5
3C
4
1B
4 1E
12 1K 13 2 1K 4
3E
13A 8
3D
13 1H 10
16 IE1
15 IG1
10 IK1 2IJ2 1IJ2 9IJ2 7IG2
4 3
2 IE2 6 IE2 1 IE2 5 IE2 11 IE2 10 I E2 MEA
IG
1A
C14 A 3F
43E 3
Y
Y
B±R R
W± R R
BR±Y
P
W
G±W
Y± B
P± B R±W
R±LL
W±B
R±B
LG±R P
LG
G±R B±W
Y± B
Y±B
P±B
P±B
R± B
LG±R P
LG
G± R W±R W±R
W
R
W± R R
BR±Y
P
W± L
W W
W±B
W±B
W±B R±L R±L B±W
16
1
20
9
23
22
3
15 10
13
10 4 1115 5
6
1
3 4 18 13 24 25 26 12 11
675
123 MC
MO
VR3
VR2
VR1
GN D
CCS
CMS
PKB
TC
PI
100A AM1
120A ALT
60A MAIN
30A AM2 30A INJ
B BAT T N&C ECT I DL OD SPD STP+ STP± LY±B
3H
12
B
(
US A )
( CANADA )
6
W
4
W± R
BATTERY CRUI SE CONT ROL
INDICATOR LI GHT
[COMB. METER]
T6
TDCL
(Tot al Diagnos tic
Communic ation Link )C3
CHECK
CONNECTOR
F9
FUSE BLOCK
C15
CRUISE
CONTROL SW
[ COMB. SW]CA NCEL
RE SUME/
ACCEL SET/
COAST
MA I N
C8
CRUISE CONTROL ACTUATOR
POTENTIO METER
MAGNETI C
CLUTCH
C1 9
CRUI SE CONT ROL E CU
S12
STOP LIGHT SW From Stop Light SW
<4±6><5±6> Fr om º STOPº Fus e
<4±6><5±6> Fr om Combination Meter
< 21±5>
Fr om Engine and ECT ECU
<3±4> 10A GAUGE
15A ECU±IG 10A DOME 7. 5A ST
B±WB±Y W
40A IGSW
Cruise Control
14
5
47
14
9
Power
Source
C1 2 B , C14 A
TC
A/ D TC
To Parking Brake SW
< 21±2>
13 IG1
P± B
P±B
To Engine and ECT ECU
<3±3> Fr om Engine and ECT ECU
<3±2>8
I15
IGNITION SW
Ins trument panel
br ace LHFront side of
r ight fender
2
1
CRUISE CONTROL INDICATOR
LIGHT[ COMB. METER] 20 B
C12 B VR1 VR2 VR3 MC L
MO
GND
1221
IJ16
IJZ10
B±W
B±W B
B±W B±W
B±W
B±W
B±W
2
(
M/T )
( A/T )
C2 3
CL UTCH
START SW
C24
CRUISE CONTROL
CLUTCH SW
( M/T )
( A/T )
10 11 12 13 17 18 19 20 21 12345 6789
14 15 16
17 18
1 2345 6789 10
23
22
21
20
19
15
14
13
12
11 16
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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
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44
POWER SOURCE (Current Flow Chart)
The chart below shows the route by which current flows from the battery to \
each electrical source
(Fusible Link, Circuit Breaker, Fuse, etc.) and other parts.
The next page and following pages show the parts to which each electrica\
l source outputs current.
Taillight
Relay (Point Side)
30A AM260A MAIN 50A DEFOG
60A HEATER
7.5 TRAC
40A IG SW
120A ALT
Starter Relay
(Point Side)
Headlight Relay
(Point Side)
30A EFI
15A TEL
10A DOME
20A RADIO No. 1
25A HAZ±HORN
Theft Deterrent and
Door Lock ECU
15A HEAD RH
(USA) 15A HEAD LH
(USA)
Dimmer Relay
(Coil Side)
Starter
15A STOPIgnition SW
(AM1)
30A DOOR
15A TAIL
Alternator
ABS Motor Relay
(Point Side)
Defogger
Relay
Starter ABS
Actuator
10A MIR±HTR
15A ECU±B 7.5A PANEL
7.5 IGN
Engine ECU Traction Brake
Actuator
30A INJ
60A ABS No.1
Traction Brake
Main Relay
(Point Side)
ABS
Actuator Relay
30A POWER
Integration
Relay
100A AM1
Seat Heater
Relay (Point Side)
7.5 ALT SENCING
30A ABS No.2 Headlight
Relay
(Coil Side)
Traction Motor
Relay (Point Side)Traction Pump
and Motor Dimmer Relay
(Point Side) Ignition SW
(AM2)
Taillight
Relay (Coil Side)
15A HEAD (LH±LWR)
(CANADA)
15A HEAD (RH±LWR)
(CANADA)
Engine and
ECT ECU
15A HEAD (LH±UPR)
(CANADA)
15A HEAD (RH±UPR)
(CANADA) ABS and
Traction ECU
Battery
[LOCATION](1): J/B No. 1 (See page
20)(2): R/B No. 2 (See page 19)(3): R/B No. 4 (See page 23)
20
19 22
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49
F16 F18 I1H8
G2
G1 H1 H3 H2 H4 H5 I2 I14 I15 L7 I16 L2 M2L6
L3 M4
80
194
111 94 101
62
68
101 11 2
126
186 154
162
68 68 94
216
90 86
107
H6 H7 H9 98
N1
Unlock Warning SW
[Ignition SW] Igniter No.1 Fuel Pump ECU
Glove Box Light
Headlight LH HI
Hazard SW
High Mount Stop Light
(w/ Rear Spailer) Horn LHISC ValveIgnition Key Cylinder Light
Key Inter Lock Solenoid
Moon Roof Control Relay Light Failure Sensor
Luggage Compartment
Light SW
A/T Indicator SW
Back±Up Light SW
Neutral Start SW Licence Plate Light Integration Relay Fuel Sender
Glove Box Light SW
Headlight RH HI
Headlight LH LO
Headlight RH LO
Horn RH
High Mount Stop Light
(w/o Rear Spailer)
Luggage Compartment
Light SW
Moon Roof Motor
86
98
108
182
216
82
91
94
102
82
216 90
104
(4)
: R/B No. 5 (See page ) 22
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56
POWER SOURCE
AM2 AM1
ACC
IG 1
IG 2
321 6 411
ST1
1B
2
1J 5
1J 6
1J 3
1J 8 1K
13
1K 4
1J
4
1B
4
1J
7 I24
I33
I11 P
N 2
3
IE1
16
IJ16
3421314 59 7
116
W
WB
B
B
B±R
B±W B±W
W±L
B
B±O P±L B
B
B
W±L R
W±R
W±R
B
W±R Y
W±L
W±R
W
W±R
B±Y
B±W P±L
B±O
B±W
B±W
B±W
B±WW
B±R
15A ECU±B
15A STOP
30A POWER
30A DOOR
TAILLIGHT
RELAY 15A TAIL
7. 5A PANEL BATTERY
15A ECU±IG
7. 5A ENGINE
20A W IPER
10A GAUGE 20A TURN
10A HEATER
7. 5A ST
7. 5A IGN 15A CIG
7. 5A RADIO NO. 2
40A
IGSW
NEUTRAL
START SW
TO ENGINE AND ECT ECUTO CRUISE CONTROL ECU
TO ABS ACTUATOR RELAY,
ABS MOTOR RELAY AND
TRACTION BRAKE
ACTUATOR RELAYTO ALTERNATOR º Bº
IGNITION SW
FUSE BLOCK
TO TRACTION MOTOR RELAY100A AM1
60A ABS NO. 1
30A INJ
120A ALT 30A AM2
30A ABS NO. 2 60A MAIN
F9
N1
I15
5
1 3
2
2
6
3 4 1
5
1 2IJ2
8 B
B±W
B
B
(
M/T )
(
M/T )
C23
CLUTCH START SW
(
A/T )
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154
POWER SEAT (w/ DRIVING POSITION MEMORY)
PRND 2 L146578 9
GR
R±B
L
G±W G
W
A/T INDICATOR SW
[NEUTRAL START SW AND BACK±UP LIGHT SW]
N1
IT1
12
1I
10 1H 12
1C
10 1H
1
A
6
STOP A
15
P
A
3 RCL+
A
10 RCL±
B
16 SSRS
B
14 SSRR
B
6 PVCC
B
5 SSFV
B
15 SSRV
2
3 13
1265
2 13 2
13
M
B28
B26 B27
BU1
7
Ba16
Ba1
8 1 2
IJ1
10
GR
V V
V
BR±B
BR±B BR±B
BR±B
BR±B
BR±BLG
V
Y±R Y±B
V
V±W
LG±R V
Y±G V
BR±B
G±W G±W G±W W
Y
GR
GR
Y
Y
VV LG±R
Y±G
V±W
Y±B
Y±R LG
FROM POWER SOURCE SYSTEM
(
SEE PAGE 56 )
15A
STOP 10A
GAUGE
STOP LIGHT
SW
POWER SEAT ECU
(FOR DRIVE R' S SEA T )
SLIDE
POSITION
SENSOR
( FOR
DRIVE R' S SEA T )POWER SEAT MOTOR
(
FOR DRIVER' S SEAT
RECLINING MOTOR
CONTROL ) FRONT
VERTICAL
POSITION
SENSOR
RE AR
VEATICAL
POSITION
SENSOR
S20
P16 F19 R19
P10 , P 1 1
S12
AB
B261
B
( M/T )
PARKING
BRAKE SW
P
3 (
A/T )
BR±B
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159
RETURN OPERATION
WHEN THE SEAT BACK IS RAISED UP FROM THE WALK±IN POSITION AND RETURNED TO THE UPRIGHT LOCK POSITION,
RECLINING LIMIT SWITCH NO. 1 OPERATES AND A SIGNAL IS INPUT TO TERMINAL RRSW OF THE POWER SEAT ECU " TERMINAL
SLD± " TERMINAL 2 OF POWER SEAT MOTOR (FOR PASSENGER'S SEAT SLIDE CONTROL) " MOTOR " TERMINAL 1 " TERMINAL
SLD+ OF ECU " TERMINAL GND " GROUND . THIS CAUSES THE SEAT TO SLIDE BACK TO A POSITION 120 MM FROM THE MOST
REAR POSITION, COMPLETING RETURN OPERATION. HOWEVER, IF THE SEAT IS POSITIONED WITHIN 120 MM OF THE MOST REAR
POSITION, RETURN OPERATION DOES NOT OCCUR, THUS MAINTAINING SUFFICIENT SPACE FOR THE REAR SEAT PASSENGER.
D10 DOOR LOCK MOTOR, DOOR UNLOCK DETECTION SW AND DOOR OPEN DETECTION SW LH
3±6 : CLOSED WITH FRONT LH DOOR OPEN
N 1 A/T INDICATOR SW [NEUTRAL START SW]
9±1 : CLOSED WITH SHIFT LEVER AT ªPº POSITION
P10(A), P11(B) POWER SEAT ECU (FOR DRIVER'S SEAT)
(A) 6±GROUND : APPROX. 12 VOLTS WITH STOP LIGHT SW ON
(B) 7±GROUND : ALWAYS APPROX. 12 VOLTS
(A) 7±GROUND : APPROX. 12 VOLTS WITH IGNITION SW ON
(A) 15±GROUND : APPROX. 12 VOLTS WITH IGNITION SW ON AND SHIFT LEVER AT ªPº RANGE
(A) 2±GROUND : APPROX. 12 VOLTS WITH DRIVER'S SEAT AT FRONT SLIDE OPERATION
(A) 9±GROUND : APPROX. 12 VOLTS WITH DRIVER'S SEAT AT REAR SLIDE OPERATION
(A) 4±GROUND : APPROX. 12 VOLTS WITH DRIVER'S SEAT AT FRONT VERTICAL UP OPERATION
(A) 11±GROUND : APPROX. 12 VOLTS WITH DRIVER'S SEAT AT FRONT VERTICAL DOWN OPERATION
(A) 13±GROUND : APPROX. 12 VOLTS WITH DRIVER'S SEAT AT REAR VERTICAL UP OPERATION
(A) 12±GROUND : APPROX. 12 VOLTS WITH DRIVER'S SEAT AT REAR VERTICAL DOWN OPERATION
(B) 18±GROUND : ALWAYS CONTINUITY
(A) 5, (A) 14±GROUND : ALWAYS APPROX. 12 VOLTS
(A) 1, (A) 8±GROUND : ALWAYS CONTINUITY
P 8 POWER SEAT CONTROL SW (FOR DRIVER'S SEAT)
4±14 : CLOSED WITH DRIVER'S SEAT AT FRONT RECLINING OPERATION
3±14 : CLOSED WITH DRIVER'S SEAT AT REAR RECLINING OPERATION
1±14 : CLOSED WITH DRIVER'S SEAT AT FRONT SLIDE OPERATION
2±14 : CLOSED WITH DRIVER'S SEAT AT REAR SLIDE OPERATION
5±14 : CLOSED WITH DRIVER'S SEAT AT FRONT VERTICAL UP OPERATION
6±14 : CLOSED WITH DRIVER'S SEAT AT FRONT VERTICAL DOWN OPERATION
9±14 : CLOSED WITH DRIVER'S SEAT AT REAR VERTICAL UP OPERATION
8±14 : CLOSED WITH DRIVER'S SEAT AT REAR VERTICAL DOWN OPERATION
P12 POWER SEAT ECU (FOR PASSENGER'S SEAT)
1±GROUND : ALWAYS APPROX. 12 VOLTS
8±GROUND : ALWAYS APPROX. 12 VOLTS
7±GROUND : APPROX. 12 VOLTS WITH PASSENGER'S SEAT AT FRONT SLIDE OPERATION
17±GROUND : APPROX. 12 VOLTS WITH PASSENGER'S SEAT AT REAR SLIDE OPERATION
S12 STOP LIGHT SW
2±1 : CLOSED WITH STOP LIGHT SW ON
SERVICE HINTS
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167
4. AUTO RETURN OPERATION
WHEN THE STEERING IS IN ªAUTO AWAYº CONDITION AND THE IGNITION KEY IS INSERTED INTO THE IGNITION KEY CYLINDER
(UNLOCK WARNING SW ON), A SIGNAL IS INPUT TO TERMINAL UWSW OF TILT AND POWER TELESCOPIC ECU.
AS A RESULT, THE TILT AND POWER TELESCOPIC ECU OPERATES AND THE CURRENT TO TERMINAL +B OF TILT AND POWER
TELESCOPIC ECU FLOWS FROM TERMINAL TEM± OF TILT AND POWER TELESCOPIC ECU "TERMINAL 4 OF COMB. SW "
TERMINAL 1 OF TELESCOPIC CONTROL MOTOR "TERMINAL 2 " TERMINAL 1 OF COMB. SW " TERMINAL TEM+ OF TILT AND
POWER TELESCOPIC ECU " TERMINAL GND2 "GROUND , AND AT THE SAME TIME, CURRENT FLOWS FROM TERMINAL TIM± OF
TILT AND POWER TELESCOPIC ECU "TERMINAL 10 OF COMB. SW "TERMINAL 1 OF TILT CONTROL MOTOR "TERMINAL 2 "
TERMINAL 1 OF COMB. SW "TERMINAL TIM+ OF TILT AND POWER TELESCOPIC ECU "TERMINAL GND2 "GROUND , CAUSING
BOTH THE TILT CONTROL MOTOR AND TELESCOPIC CONTROL MOTOR TO ROTATE. THE MOTORS CONTINUE TO ROTATE UNTIL
THE SIGNALS INPUT FROM THE TILT POSITION SENSOR TO TERMINAL TIS OF TILT AND POWER TELESCOPIC ECU AND FROM THE
TELESCOPIC POSITION SENSOR TERMINAL TES OF TILT AND POWER TELESCOPIC ECU (SIGNALS INFORMING THE ECU OF THE
CURRENT POSITION OF THE STEERING) MATCH THE POSITION MEMORIZED BY THE ECU PRIOR TO AUTO AWAY OPERATION.
IN THIS WAY, THE STEERING POSITION IS AUTOMATICALLY RETURNED TO THE ORIGINAL POSITION.
WHEN THE IGNITION SW IS TURNED FROM OFF TO ON OR THE SHIFT LEVER IS SHIFTED TO A POSITION OTHER THAN P OR N,
AUTO OPERATION IS STOPPED.
C15 TILT AND POWER TELESCOPIC UNIT [COMB. SW]
4±6 : APPROX. 160
WITH TELESCOPIC LONG OPERATION
: APPROX. 360
WITH TILT UP OPERATION
: APPROX. 790
WITH TELESCOPIC SHORT OPERATION
: APPROX. 2.0K
WITH TILT DOWN OPERATION
8±7 : CONTINUITY WITH AUTO SW OFF
8±4 : APPROX. 5K

T 7 (D) TELESCOPIC POSITION SENSOR
6±3 : APPROX. 5K

D10 DOOR LOCK MOTOR, DOOR UNLOCK DETECTION SW AND DOOR OPEN DETECTION SW LH
3±6GROUND :CLOSED WITH FRONT DOOR LH OPEN
D12 DRIVING POSITION MEMORY AND RETURN SW
2±3 : CLOSED WITH DRIVING POSITION MEMORY SW (NO. 1) ON
1±3 : CLOSED WITH DRIVING POSITION MEMORY SW (NO. 2) ON
4±3 : CLOSED WITH DRIVING POSITION MEMORY SW (SET) ON
I15 UNLOCK WARNING SW [IGNITION SW]
9±10: CLOSED WITH IGNITION KEY IN CYLINDER
N 1 A/T INDICATOR SW [NEUTRAL START SW]
9±1 : CLOSED WITH SHIFT LEVER AT P POSITION
T10, T11 TILT AND POWER TELESCOPIC ECU
(A) 4±GROUND : ALWAYS APPROX. 12 VOLTS
(A) 1±GROUND : APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION
(B) 18±GROUND : ALWAYS APPROX. 12 VOLTS
(A) 6±GROUND : APPROX. 12 VOLTS WITH IGNITION SW ON AND SHIFT LEVER AT ªPº RANGE
(B) 10±GROUND : CONTINUITY WITH IGNITION KEY IN CYLINDER
(A) 7±GROUND : ALWAYS CONTINUITY
(B) 8±GROUND : ALWAYS CONTINUITY
(B) 2±GROUND : CONTINUITY WITH FRONT DOOR LH OPEN
(B) 3±GROUND : CONTINUITY WITH DRIVING POSITION MEMORY SW (NO. 1) ON
(B) 12±GROUND : CONTINUITY WITH DRIVING POSITION MEMORY SW (NO. 2) ON
(B) 11±GROUND : CONTINUITY WITH DRIVING POSITION MEMORY SW (SET) ON
(A) 10±GROUND : APPROX. 12 VOLTS WITH TILT UP OPERATION
(A) 3±GROUND : APPROX. 12 VOLTS WITH TILT DOWN OPERATION
(A) 2±GROUND : APPROX. 12 VOLTS WITH TELESCOPIC SHORT OPERATION
(A) 11±GROUND : APPROX. 12 VOLTS WITH TELESCOPIC LONG OPERATION
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
C1728N 127T 732
D1030P 329T10B29
D1230P1127T11A29
I1529R 732
SERVICE HINTS
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