1991 LEXUS SC400 stop start

139
(FOR ABS)
THIS SYSTEM CONTROLS THE RESPECTIVE BRAKE FLUID PRESSURES ACTING ON THE DISC\
BRAKE CYLINDERS OF THE RIGHT
FRONT WHEEL, LEFT FRONT WHEEL AND REAR WHEELS WHEN THE BRAKES ARE APPLIED IN \
A PANIC STOP SO THAT THE
WHEELS DO NOT LOCK. THIS RESULTS IN IMPROVED DIRECTIONALLY STABILITY AND STEERABILITY DURING PANIC BRAKING.
1. INPUT SIGNALS
(1) SPEED SENSOR SIGNALTHE SPEED OF THE WHEELS IS DETECTED AND INPUT TO TERMINALS FL+, FR+, RL+ AND RR+ OF THE ABS AND TRACTION
ECU.
(2) STOP LIGHT SW SIGNAL A SIGNAL IS INPUT TO TERMINAL STP OF THE ABS AND TRACTION ECU WHEN THE BRAKE PEDAL IS OPERATED.
(3) PARKING BRAKE SW SIGNAL A SIGNAL IS INPUT TO TERMINAL PKB OF THE ABS AND TRACTION ECU WHEN THE PARKING BRAKE IS OPERATED.
2. SYSTEM OPERATION
DURING SUDDEN BRAKING, THE ABS AND TRACTION ECU WHICH HAS SIGNALS INPUT FROM E\
ACH SENSOR CONTROLS THE
CURRENT FLOWING TO THE SOLENOID INSIDE THE ACTUATOR AND LETS THE HYDRAULIC PRESSURE ACTING ON EACH WHEEL
CYLINDER ESCAPE TO THE RESERVOIR. THE PUMP INSIDE THE ACTUATOR IS ALSO OPERATING AT THIS TIME AND IT RETURNS
THE BRAKE FLUID FROM THE RESERVOIR TO THE MASTER CYLINDER, THUS PREVENTING LOCKING OF THE VEHICLE WHEELS.
IF THE ECU JUDGES THAT THE HYDRAULIC PRESSURE ACTING ON THE WHEEL CYLINDER IS INSUFFICIENT, THE CURRENT
ACTING ON SOLENOID IS CONTROLLED AND THE HYDRAULIC PRESSURE IS INCREASED, HOLD\
ING OF THE HYDRAULIC
PRESSURE IS ALSO CONTROLLED BY THE COMPUTER, BY THE SAME METHOD AS ABOVE. BY REP\
EATED PRESSURE REDUCTION,
HOLDING AND INCREASE ARE REPEATED TO MAINTAIN VEHICLE STABILITY AND TO IMPROVE STEERABILITY DURING SUDDEN
BRAKING.
(FOR TRACTION CONTROL)
THE TRACTION CONTROL SYSTEM IS A SYSTEM WHEREBY THE ªABS AND TRACTION ECUº AND ªTRACTION ECUº\
CONTROLS THE
ENGINE TORQUE AND THE HYDRAULIC PRESSURE OF THE WHEEL CYLINDER OF THE DRIVING WHEELS IN ORDER TO CONTROL
SPINNING OF THE DRIVING WHEELS WHEN STARTING OFF AND ACCELERATING, AND PROVIDE THE MOST APPROPRIATE DRIVING
FORCE IN RESPONSE TO THE ROAD CONDITIONS FOR VEHICLE STABILITY.
TRACTION CONTROL OPERATION
VEHICLE SPEED SIGNALS FROM THE SPEED SENSOR INSTALLED ON EACH WHEEL ARE INPUT TO THE ABS AND TRACTION ECU.
WHEN THE ACCELERATOR PEDAL IS DEPRESSED WHILE DRIVING ON A SLIPPERY ROAD AND THE DRIVING WHEEL (REAR WHEEL)
SLIPS, IF THE ROTATION OF THE REAR WHEEL EXCEEDS THE ROTATION OF THE FRONT WHEELS FOR A SPECIFIED PERIOD, THE
ECU JUDGES THAT THE REAR WHEEL IS SLIPPING.
WHEN THIS OCCURS, CURRENT FLOWS FROM TRACTION ECU TO SUB THROTTLE ACTUATOR TO CLOSE THE SUB THROTTLE
VALVE. THE THROTTLE VALVE OPENING ANGLE SIGNAL IS OUTPUT FROM TERMINAL VTA OF SUB THROTTLE POSITION SENSOR
TO TERMINAL VTA2 OF ENGINE AND ECT ECU TO KEEP THE ENGINE RPM AT THE MOST SUITABLE LEVEL FOR THE DRIVING
CONDITIONS AND REDUCE SLIP OF THE DRIVING WHEEL. AT THE SAME TIME, OPERATION OF THE ABS AND TRACTION ECU
CAUSE THE TRACTION BRAKE ACTUATORS (ACC CUT, M/C CUT, RESERVOIR CUT SOLENOID) TO TURN ON TO SWITCH THE
HYDRAULIC CIRCUIT TO ªTRACTIONº MODE.
IN THIS CASE, SIGNALS ARE INPUT FROM TERMINAL SRR OF ABS AND TRACTION ECU TO TERMINAL (B)6 OF ABS ACTUATOR, AND
FROM TERMINAL SRL OF ABS AND TRACTION ECU TO TERMINAL (B)1 OF ABS ACTUATOR, CONTROLLING THE REAR WHEEL
SOLENOID IN THE ABS ACTUATOR AND INCREASING THE HYDRAULIC PRESSURE OF THE WHEEL CYLINDER IN ORDER \
TO
PREVENT SLIP.
TO MAINTAIN THE HYDRAULIC PRESSURE OF THE REAR WHEELS, THE REAR WHEEL SOLENOID I\
NSIDE THE ABS ACTUATOR IS
PUT IN ªHOLDº MODE AND KEEPS THE HYDRAULIC PRESSURE TO THE BRAKE CYLINDER CONSTANT.
WHEN THE BRAKE CYLINDER HYDRAULIC PRESSURE IS REDUCED, THE PRESSURE REDU\
CTION MODE REDUCES AND CONTROLS
THE HYDRAULIC PRESSURE.
SYSTEM OUTLINE
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227
4. OPERATION OF AIR MIX CONTROL SERVO MOTOR
WHEN THE TEMPERATURE SW IS TURNED TO THE ªCOOLº SIDE, THE CURRENT FLOWS FROM TERMINAL MC OF A/C CONTROL
ASSEMBLY " TERMINAL 4 OF AIR MIX CONTROL SERVO MOTOR " MOTOR " TERMINAL 5 " TERMINAL MH OF A/C CONTROL
ASSEMBLY " GROUND AND THE MOTOR ROTATES. THE DAMPER OPENING ANGLE AT THIS TIME IS INPUT FROM TERMINAL 1 OF
SERVO MOTOR TO TERMINAL TP OF A/C CONTROL ASSEMBLY, THIS IS USED TO DETERMINE THE DAMPER STOP POSITION AND
MAINTAIN THE SET TEMPERATURE.
WHEN THE TEMPERATURE CONTROL SW IS TURNED TO THE ªHOTº SIDE, THE CURRENT FLOWS FROM SERVO MOTOR "
TERMINAL MH OF A/C CONTROL ASSEMBLY " TERMINAL 5 OF AIR MIX CONTROL SERVO MOTOR " MOTOR " TERMINAL 1 "
TERMINAL MC OF A/C CONTROL ASSEMBLY, ROTATING THE MOTOR IN REVERSE AND SWITCHING THE DAMPER FROM ªCOOLº TO
ªHOTº SIDE.
5. AIR CONDITIONER OPERATION
THE A/C CONTROL ASSEMBLY RECEIVES VARIOUS SIGNALS, I.E., THE ENGINE RPM FROM THE IGNITER, OUTLET TEMPERATURE
SIGNAL FROM THE A/C THERMISTOR, COOLANT TEMPERATURE FROM THE WATER TEMP. SENSOR AND THE LOCK SIGNAL FROM
THE A/C COMPRESSOR, ETC.
WHEN THE ENGINE IS STARTED AND THE A/C SW (A/C CONTROL ASSEMBLY) IS ON, A SIGNAL IS INPUT TO THE ECU. (BUILT IN THE
A/C CONTROL ASSEMBLY).
AS A RESULT, THE GROUND CIRCUIT IN A/C CONTROL ASSEMBLY IS CLOSED AND CURRENT FLOWS FROM HEATER FUSE (10A) TO
TERMINAL 2 OF MAGNETIC CLUTCH RELAY " TERMINAL 3 " TERMINAL ACMG OF ENGINE AND ECT ECU " TERMINAL E OF A/C
CONTROL ASSEMBLY " GROUND , TURNING THE MAGNETIC CLUTCH RELAY ON, SO THAT THE MAGNETIC CLUTCH IS ON AND THE
A/C COMPRESSOR OPERATES.
AT THE SAME TIME, THE ENGINE AND ECT ECU DETECTS THE MAGNETIC CLUTCH IS O\
N AND THE A/C COMPRESSOR OPERATES.
OPEN DIRECTION TO AVOID LOWERING THE ENGINE RPM DURING A/C OPERATING.
WHEN ANY OF THE FOLLOWING SIGNALS ARE INPUT TO THE A/C CONTROL ASSEMBLY, THE CONTROL ASSEMBLY OPERATES TO
TURN OFF THE AIR CONDITIONING.
* ENGINE HIGH TEMP. SIGNAL IS HIGH.
* COOLANT HIGH TEMP. SIGNAL IS HIGH.
* A SIGNAL THAT THE TEMPERATURE AT THE AIR OUTLET IS LOW.
* A SIGNAL THAT THERE IS A LARGE DIFFERENCE BETWEEN ENGINE RPM AND COMPRESSOR RPM.
* A SIGNAL THAT THE REFRIGERANT PRESSURE IS ABNORMALLY HIGH OR LOW.
WhereEverybodyKnowsYourName

149
1K
4 1I
10
B
9B 64 A 12
1
IJ2
2IJ2 1IJ1
6
PARKING
BRAKE SWM42
4 31
5
7
6
23
1 25A
STOP
7. 5A
ST
POTENTIO METER
CRUIS E CONTROL ACTUATOR GN DL
MC
MO
VR3
VR2
VR1
MAGNETIC
CLUTCH
S2 IDL1 OD1
ECT IDL OD VR1 VR2 VR3 MC MO L STP±
N& C STP+
CRUISE CONTROL ECU
STOP
LIGHT
SW
B±W B±W
W
B±W
W
W
G±W BR±Y
R
W±R
W±R
R
BR±Y
R±B
LG±R P
LG
G±R
W
R±L R±B
LG±R P
LG
G±R B±W
W±B
I9
S12
C19
P3C8
FROM POWER SOURCE SYSTEM
(
SEE PAGE 56 )
R±W
B
PKB
ENGINE AND ECT ECU E9 ,E10
I7
EA
IE 2
10
IE2
11
IE2
5
IE2
1
IE2
6
IE2
2
IG1
19
IJ2
9
B (
CANA DA )
(
USA )
R±L
22 23 9 3 24 25 26 12 11 10 16 1
A B IJ2
10
I9
C24 C23
CLUTCH
START SW CRUISE
CONTROL
CLUTCH SW(
A/T )
B±W
BB±W
B±W
B±W
(
A/T )
(
A/T )
1
2
2
21
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150
CRUISE CONTROL
CURRENT IS APPLIED AT ALL TIMES THROUGH STOP FUSE TO TERMINAL 1 OF THE CONTROL ECU TERMINAL 2 OF STOP LIGHT
SWITCH, AND ALSO THROUGH THE DOME FUSE TO TERMINAL 15 OF CRUISE CONTROL ECU.
WITH THE IGNITION SWITCH TURNED TO ON, THE CURRENT FLOWS THROUGH GAUGE FUSE TO TERMINAL (A)1 OF COMBINATION
METER AND THE CURRENT THROUGH ECU±IG FUSE FLOWS TO TERMINAL 14 OF CRUISE CONTROL ECU.
WHEN THE IGNITION SWITCH IS ON AND THE CRUISE CONTROL MAIN SWITCH IS TUR\
NED ON, A SIGNAL IS INPUT FROM TERMINAL
15 OF CRUISE CONTROL MAIN SWITCH TO TERMINAL 4 OF CRUISE CONTROL ECU. AS A RESULT, THE CRUISE CONTROL ECU
FUNCTIONS AND THE CURRENT TO TERMINAL 14 OF CRUISE CONTROL ECU TO TERMINAL 13 OF CRUISE CONTROL ECU "
GROUND, AND THE CRUISE CONTROL SYSTEM IS IN A CONDITION READY FOR OPERATION.
AT THE SAME TIME, THE CURRENT THROUGH THE GAUGE FUSE FLOWS FROM TERMINAL (A)1 OF CRUISE CONTROL INDICATOR
LIGHT " TERMINAL (B)20 "TERMINAL 5 OF CRUISE CONTROL ECU "TERMINAL 13 " TO GROUND, CAUSING THE CRUISE
CONTROL INDICATOR LIGHT TO LIGHT UP, INDICATING THAT THE CRUISE CONTROL IS READY FOR OPERATION.
1. SET OPERATION
WHEN THE CRUISE CONTROL MAIN SWITCH IS TURNED ON AND THE SET SWITCH IS PUSHE\
D WITH THE VEHICLE SPEED WITHIN
THE SET LIMIT (APPROX. 40 KM/H, 2.5 MPH TO 200 KM/H, 124 MPH), A SIGNAL IS INPUT TO TERMINAL 18 OF THE CRUISE CONTROL
ECU AND THE VEHICLE SPEED AT THE TIME THE SET SWITCH IS RELEASED IS MEMORIZED IN THE ECU AS THE SET\
SPEED.
2. SET SPEED CONTROL
DURING CRUISE CONTROL DRIVING, THE ECU COMPARES THE SET SPEED MEMORIZED IN THE ECU WITH THE ACTUAL VEHICLE
SPEED INPUT INTO TERMINAL 20 OF THE CRUISE CONTROL ECU FROM THE SPEED SENSOR, AND CONTROLS THE CRUIS\
E
CONTROL ACTUATOR TO MAINTAIN THE SET SPEED.
WHEN THE ACTUAL SPEED IS LOWER THAN THE SET SPEED, THE ECU CAUSES THE CURREN\
T TO THE CRUISE CONTROL
ACTUATOR TO FLOW FROM TERMINAL 12 " TERMINAL 6 OF CRUISE CONTROL ACTUATOR "TERMINAL 7 " TERMINAL 11 OF
CRUISE CONTROL ECU. AS A RESULT, THE MOTOR IN THE CRUISE CONTROL ACTUATOR IS ROTATED TO OPEN THE THROTTLE
VALVE AND THE THROTTLE CABLE IS PULLED TO INCREASE THE VEHICLE SPEED. WHEN THE ACTUAL DRIVING SPEED IS HIGHER
THAN THE SET SPEED, THE CURRENT TO CRUISE CONTROL ACTUATOR FLOWS FROM TERMINAL 11 OF ECU "TERMINAL 7 OF
CRUISE CONTROL ACTUATOR "TERMINAL 6 "TERMINAL 12 OF CRUISE CONTROL ECU.
THIS CAUSES THE MOTOR IN THE CRUISE CONTROL ACTUATOR TO ROTATE TO CLOSE THE THROTTLE VALVE AND RETURN THE
THROTTLE CABLE TO DECREASE THE VEHICLE SPEED.
3. COAST CONTROL
DURING THE CRUISE CONTROL DRIVING, WHILE THE COAST SWITCH IS ON, THE CRUISE CONTROL ACTUATOR RETURNS THE
THROTTLE CABLE TO CLOSE THE THROTTLE VALVE AND DECREASE THE DRIVING SPEED. THE VEHICLE SPEED WHEN THE COAST
SWITCH IS TURNED OFF IS MEMORIZED AND THE VEHICLE CONTINUES AT THE NEW SET SPEED.
4. ACCEL CONTROL
DURING CRUISE CONTROL DRIVING, WHILE THE ACCEL SWITCH IS TURNED ON, THE CRUISE\
CONTROL ACTUATOR PULLS THE
THROTTLE CABLE TO OPEN THE THROTTLE VALVE AND INCREASE THE DRIVING SPEED.
THE VEHICLE SPEED WHEN THE ACCEL SWITCH IS TURNED OFF IS MEMORIZED AND THE \
VEHICLE CONTINUES AT THE NEW SET
SPEED.
5. RESUME CONTROL
UNLESS THE VEHICLE SPEED FALLS BELOW THE MINIMUM SPEED LIMIT (APPROX. 40 KM/H, 25 MPH) AFTER CANCELING THE SET
SPEED BY THE CANCEL SWITCH, PUSHING THE RESUME SWITCH WILL CAUSE THE VEHICLE \
TO RESUME THE SPEED SET BEFORE
CANCELLATION.
6. MANUAL CANCEL MECHANISM
IF ANY OF THE FOLLOWING OPERATIONS OCCURS DURING CRUISE CONTROL OPERATION, THE SAFETY MAGNETIC CLUTCH OF
THE ACTUATOR TURNS OFF AND THE MOTOR ROTATES TO CLOSE THE THROTTLE VALVE AND THE CRUISE CONTROL IS
RELEASED.
* PLACING THE SHIFT LEVER IN ªNº RANGE (NEUTRAL START SWITCH ON)). ªSIGNAL INPUT TO TERMINAL 2 OF ECUº
* DEPRESSING THE BRAKE LEVER (STOP LIGHT SWITCH ON). ªSIGNAL INPUT TO TERMINAL 16 OF ECUº
* PULLING THE PARKING BRAKE PEDAL (PARKING BRAKE SWITCH ON). ªSIGNAL INPUT TO TERMINAL 3 OF ECUº
* PUSHING THE CANCEL SWITCH (CANCEL SWITCH ON). ªSIGNAL INPUT TO TERMINAL 18ª
SYSTEM OUTLINE
WhereEverybodyKnowsYourName

66
.
ENGINE CONTROL
THIS SYSTEM UTILIZES AN ECU AND MAINTAINS OVERALL CONTROL OF THE ENGINE, TRANSMISSION AND SO ON. AN OUTLINE O\
F
THE ENGINE CONTROL IS EXPLAINED HERE.
1. INPUT SIGNALS
(1) WATER TEMP. SIGNAL CIRCUITTHE WATER TEMP. SENSOR DETECTS THE ENGINE COOLANT TEMP. AND HAS A BUILT±IN THERMISTOR WITH A RESISTANCE
WHICH VARIES ACCORDING TO THE WATER TEMP. THE WATER TEMP. IS INPUT INTO TERMINAL THW OF ENGINE CONTROL
ECU AS A CONTROL SIGNAL.
(2) INTAKE AIR TEMP. SIGNAL CIRCUIT THE INTAKE AIR TEMP. SENSOR IS INSTALLED IN THE AIR FLOW METER AND DETECTS THE INTAKE AIR TEMP., WHICH IS INPUT
AS A CONTROL SIGNAL TO TERMINAL THA OF ENGINE CONTROL ECU.
(3) OXYGEN SENSOR SIGNAL CIRCUIT THE OXYGEN DENSITY IN THE EXHAUST EMISSION IS DETECTED AND INPUT AS A CONTR\
OL SIGNAL FROM THE OXYGEN
SENSOR NO. 1 AND NO. 2 TO TERMINALS OX1, OX2 OF THE ECU AND FROM THE OXYGEN SENSOR SUB (FOR CALIFORNIA) TO
TERMINAL OX3 OF THE ECU.
TO STABILIZE DETECTION PERFORMANCE BY THE OXYGEN SENSOR SUB (FOR CALIFORNIA)\
IS WARMED. THIS HEATER IS
ALSO CONTROLLED BY THE ECU (HT).
(4) RPM SIGNAL CIRCUIT CRANKSHAFT POSITION IS DETECTED BY THE PICK±UP COIL INSTALLED INSIDE THE DISTRIBUTOR. CRANKSHAFT POSITION
IS INPUT AS A CONTROL SIGNAL TO TERMINALS G1 AND G2 OF THE ECU, AND RPM IS INPUT TO TERMINAL NE.
(5) THROTTLE SIGNAL CIRCUIT THE THROTTLE POSITION SENSOR DETECTS THE THROTTLE VALVE OPENING ANGLE AS A CONTROL SIGNAL, WHICH IS
INPUT INTO TERMINAL VTA1 OF THE ECU. WHEN THE VALVE IS COMPLETELY CLOSED, THE CONTROL SIGNAL IS INPUT INTO
TERMINAL IDL1 .
(6) VEHICLE SPEED CIRCUIT THE VEHICLE SPEED IS DETECTED BY SPEED SENSOR NO. 1 INSTALLED IN THE TRANSMISSION AND THE SIGNAL IS INPUT TO
TERMINAL SPD OF THE ECU VIA THE COMB. METER.
(7) NEUTRAL START SIGNAL CIRCUIT THE NEUTRAL START SW DETECTS WHETHER THE SHIFT POSITION IS IN NEUTRAL OR NOT, AND THE SIGNAL IS INPUT INTO
TERMINAL NSW OF THE ECU.
(8) AIRCONDITIONING SW SIGNAL CIRCUIT THE OPERATING VOLTAGE OF THE A/C MAGNETIC CLUTCH IS DETECTED AND THE SIGNAL IS INPUT INTO TERMINAL ACMG OF
ECU AS A CONTROL SIGNAL.
(9) BATTERY SIGNAL CIRCUIT VOLTAGE IS CONSTANTLY APPLIED TO TERMINAL BATT OF THE ECU. WITH THE IGNITION SW TURNED ON, THE VOLTAGE FOR
ECU START±UP POWER SUPPLY IS APPLIED TO TERMINALS +B AND +B1 OF ECU VIA EFI MAIN RELAY.
THE CURRENT FLOWING THROUGH THE IGN FUSE FLOWS TO TERMINAL IGSW OF THE ECU.
(10) INTAKE AIR VOLUME SIGNAL CIRCUIT INTAKE AIR VOLUME IS DETECTED BY THE AIR FLOW METER AND THE SIGNAL IS INPUT TO TERMINAL KS OF THE ECU AS A
CONTROL SIGNAL.
(11) STOP LIGHT SW SIGNAL CIRCUIT THE STOP LIGHT SW IS USED TO DETECT WHETHER OR NOT THE VEHICLE IS BRAKING AND THE SIGNAL IS INPUT INTO
TERMINAL STP OF THE ECU AS A CONTROL SIGNAL.
(12) STA SIGNAL CIRCUIT TO CONFIRM WHETHER THE ENGINE IS CRANKING, THE VOLTAGE APPLIED TO THE STARTER MOTOR DURING CRANKING IS
DETECTED AND THE SIGNAL IS INPUT INTO TERMINAL STA OF THE ECU AS A CONTROL SIGNAL.
(13) ENGINE KNOCK SIGNAL CIRCUIT ENGINE KNOCKING IS DETECTED BY KNOCK SENSOR NO. 1 AND NO. 2 AND THE SIGN\
AL IS INPUT INTO TERMINALS KNK1 AND
KNK2 AS A CONTROL SIGNAL.
SYSTEM OUTLINE
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69
E2022 22
1H
12
2
22
22 1I
10
P
N
3
2
1 2
EB2
1
IE1
15 IJ2
7 IJ1
10 IK1 7
IK1
6
1J
3
1E12
31 23 132
1
4
52 I32
EB1
3 EB2 1
VCC OUT GNDY
L±R
B±O B
Y
B
L±R
W
B±O
B±R B±Y
B±W
B±R B±O
B±W B±O
Y
B
L±R
W
B±O
B±R B±R
B±W
B±O
B
B
B
B±R B±R B±Y
W±B
W Y
R
L±R Y
G±W
G±W B±O B
L±O
B
B
B±WB±Y
R
L±O
NEUTRAL
START SW
FROM POWER SOURCESYSTEM(
SEE PAGE 56 )
FROM POWER SOURCE SYSTEM
(
SEE PAGE 56 )
STARTER
RELAY S3
S12N1
7. 5A
IGN
30A
EFI
15A
STOP10A
GAUGE
SPEED SENSOR NO. 1
EFI MAIN
RELAY
STOP LIGHT
SW
TO THEFT DETERRENT
ANDDOORLOCK
ECU (
ST )
TO STARTER
4
3
B±Y
B±Y EB1
8
G±W
W
2 1 IJ 2
8
1I
5
C23
CLUTCH
START
SW B
B
( A/T )
(
M/T )
(
A/T )
B±W
( M/T ) IJ1
6
(A/T )
EB
W±B
B±W
WhereEverybodyKnowsYourName

OVERALL ELECTRICAL WIRING DIAGRAM
1234
1J
7 1J
31J 6 22
1B
4 1I
51K 42 22
22
2
4
ACC
IG1
ST1 IG2
AM1 2
1
6
11 AM2
32
41 3 1
4
2
21
21
21
21
16 IE1
15 IE1 1 EB22
1BT1 2BT1 3BT1
N P
2
3
21
413
6 14
7
9 17 BT1
21 21 BK EB1J
5
1E
12 7
8
4
15
12
13 1
814 25
1
7IJ2 9IK2 IK1
3A
4
3D
13
3B 1A IK1
IK1
2 1 M 3
W
W±R
W± R W
B± Y
B±R B±R B± Y B±Y
B± R
B± R
L±Y
G±W
B±W
B±O
B±O
L±RW
B±R B±Y B
Y
B±O
B±O
B±O
B±O
B±O
B±O
GR ±YB±R B± Y
B± O
G
G
B
L±O
L±O B
R±GP
G
G
W± B GP
R± G
W± B
W± B L±Y
G±W
YY W±B
B±R
B±YB±W
B± W
W± R
B±O B±O
B±O
B± O
B±O
W
W± B
B±R3 4
G±W W± L
LG
B±Y
B±W
G± R G±Y LG
L±Y
B±R
G± Y
G±R
LG
GR±Y
B± O
B±W B± O
B±R
B±RB± Y
R±G L±Y
G±W B
Y
B
B± Y
B±R W
L±R
B± Y LG
GR±Y
R±L
W
TE1 TE2 TT
ENG
OX 2 OX 1VF1
FP +B
5
G
3
B
W
T6TDCL
C3
CHECK CONNE CT OR
E1
CHECK ENGINE WARNI NG
LIGHT[ COMB. METER]
10A
GA UGE
EFI
MAIN
RELAY
30A
EFI
N1
NE UT RA L
ST ART SW
ST ARTER
RE LA Y
F1 6
FUEL PUMP ECU
BATTERY
F15
FUEL PUMP
30A AM2
60A MAIN
120A ALT
100A AM1
30A I NJ
I11
I NJECTOR No. 6 I10
I NJECTOR No. 5 I9
I NJECTOR No. 4 I7
I NJECTOR No. 2 I8
I NJECTOR No. 3 I6
I NJECTOR No. 1
From Starter< 1±3>
To Thef t Deter rent
and Door Loc k ECU
< 17±3> F9
FUSE BL OCK
7. 5A
ST
7. 5A
IGN
40A
IGSW I15
IGNITION SW
Engine Control
2 LEXUS SC300
GR±YB±R
VF2
TE1
W
W± B
B±Y
17 18
1 2345 6789 10
23
22
21
20
19
15
14
13
12
11 16 12 34 56 78
9 10 1112 13 14 1516 1718
AB
CHECK E NGI NE WA RNI NG
LIGHT[COMB. METER] W
C14 C13 6IJ1
1EB2
IJ112
B±R
B± R
E1
3 BR
25
From Stop Light SW
<5±6><4±6>
C1 3
IG±
From Igniter
ºTACº<1±5>
B,C14 A
19
P
BR
1IJ1 IK1
4
3B
4
Power
Source
(
Cont . ne xt pa ge )
Fr om A/C Contr ol
Assembly
< 22±7> < 22±5>
TC A/ C
P±B P±L4
11
11TC
Fr om A/C Contr ol
Assembly< 22±8> P± B G± Y
IG3
3
B±R
Under the center
pillar LH Fro nt s i de o f
left f ender
7
4
2 1IJ28
B B±W
B
C23
CLUTCH
START SW (
A/T )(
M/ T )
7IJ1
3IJ1B±O B±O
(A/ T )
3 EB1B (
M/T )
*1: (
w/ Traction Control )
* 2:
(
w/oTractionControl )
* 3: (
USA Spec. )
* 4:
(
Ex. USA Sp ec. )
WhereEverybodyKnowsYourName

567 8
8LEXUSSC300(
Cont ' d )
22 11 4 14 8 1716 23
1B
5
3A
6 3E
3
3B
3 1E
11 3H 12
18 IK2 15 IK2 12 IJ 2 7IO1 8IO1
9IK2 5IK2 4IK2
2IK2 10IK1
23 E BRP
4E
TRCO 1D
BRC 5E
THFA 4D
BRFA 10 D
FRO 3D
FL O 12 D
RRO 5D
RLO 15 D
ABSO 8D
BAT 2E
IG1 6D
TC 16 E
TR5 11 D
IND 14 D
WT 5
K
15 K
1
K
7D P
16 D N
1EPKB
13 IK2 3H
7
From A/ T Indicat or SW
[ NEUTRAL START SW AND
BACK±UP LIGHT]< 3±7> 26 E
BCM
25 EB±
24 EB
11 E A
12 EA±
13 EACM
14 EGND
13 DCS W
3ES1
15 E
BM 2D
STP 21 E
TR2 6E
NE O 8E
VT H 19 E
VSH 10 E
IDL1 22 E
IDL2
6 2
16 IK2
13 IJ1 3H
14
1E
18 3A
2
1J
1
IJ IF EE
213645
BCM B± B A A± ACM 1J
52
3A
4
3D
13 1E
12 2 13 14
5EE1
1
L
To Engine and
ECT ECU< 2±8>
10A
GA U GE 7. 5A
TRAC
From Stop Light SW
<5±6><4±6>
From Trottle Position
Sensor< 2±8>
FromSubThrottlePosition
Sensor< 2±8>
WB±Y
L
V± R
P±G P±L
LG±B LG
Y±B P
R± B
V±W P±B L
V
R
B± R B± R
R±W L
GR
B
R±W GR
L V± W
P±B
WA TC TC ABS W TRC
B±Y
V± R
P±G P±L
LG±B LG
Y±B
P
R±B
R
B±R RR
R±B
B±Y
W
L±R Y
Y
L±R
G±W
Y± RP±L
V±Y
Y±L R
R±B
BR
Y± R
W± B
BR
G
W L
R Y B
B
W± B Y± R
W±B
W±B
W± B
BR L
GR
L
L
P±B
L±Y W
LG±R LG±R W P±B
V± W L±G
W
P±B
P±B
P±B
W±B
R± W
W
B±Y
TS WB
C3
CHECK
CONNECTOR T6
TDCL
(
Total Diagnstic
Communic ation Link )
TRACTION ECU ABS WARNI NG AND
TRACTION OFF INDICATOR
AND TRA CT I ON I NDI CA TOR
LI GHTABS
TRAC OFF
S8
SUB THROTTL E
ACTUATOR
T12
TRACTION CUT SW (
SHI ELDED )
ABS and Traction Control
To Parking Brake SW
(
Canada )
< 21±2>
To Brake Fluide Level SW
( USA )
< 21±2>
To Parking Brake SW
< 21±3>
C1 3 , C14 KL
T1 3 , T1 4 DE 7IJ2
L±R
ABS AND TRACTION ECU TRACTION ECUABS WARNING AND TRACTION OFF INDICATOR AND
TRA CT I ON I NDI CA TOR L I GHT
Right k ick panel Left k ickpanelRea r
side of
cylinder
head LH
G±W
E
E1
20
To Engine and
ECT ECU< 2± 8> BRBR
BR
1234 67891011
14 15 16 17 18 24
512
25 26
20
19 21 22 23 13 12345 7 891011
1214 15 16 17 18 22
6
19 20 21
13 12345678
16
15
14
13
12
11
10
9 12345678
16
15
14
13
12
11
10
9 1234 67891011
14 15 16 17 18 24
512
25 26
20
19 21 22 23 13
A
A2 4 B A2 5 CA26 DT13 DARK GRAY E T1 4 DARK GRAY
12 34 56 78
910 111213 141516 1718
17 18
1 2345 6789 10
23
22
21
20
19
15
14
13
12
11 16
K
C13 L C14 123
456
12
34
F
T 3 BLACK G T4 BLACK
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