1991 LEXUS SC400 engine

213
R 4(A) RADIO AND PLAYER
(A) 3±GROUND : APPROX. 12 VOLTS WITH IGNITION SW AT ACC OR ON POSITION
(A) 4±GROUND : ALWAYS APPROX. 12 VOLTS
S14(B) STEREO POWER AMPLIFIER
(B) 7±GROUND : ALWAYS CONTINUITY
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
A1528L 630S14B31
A3230R 2B29S22A29
C 9D28R 3C29S23B29
C20A30R 4A29T16A31
C21B30R1231T17B31
F1130R1331W 931
F1230S13A31W1031
: 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)
1C20INSTRUMENT PANEL WIRE
1E20FLOOR WIRE
: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS
CODESEE PAGEJOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)
IF136FRONT DOOR LH WIRE AND COWL WIRE (LEFT KICK PANEL)
IF236FRONT DOOR LH WIRE AND COWL WIRE (LEFT KICK PANEL)
IG236INSTRUMENT PANEL WIRE AND COWL WIRE (R/B NO. 5)
IP138FRONT DOOR RH WIRE AND COWL WIRE (RIGHT KICK PANEL)
IQ138INSTRUMENT PANEL WIRE AND CONSOLE BOX WIRE (UNDER THE INSTRUMENT PANEL CENTER)IQ238INSTRUMENT PANEL WIRE AND CONSOLE BOX WIRE (UNDER THE INSTRUMENT PANEL CENTER)
BT140FLOOR WIRE AND COWL WIRE (LEFT KICK PANEL)
BV1
BV240FLOOR NO. 3 WIRE AND CONSOLE BOX WIRE (UNDER THE INSTRUMENT PANEL CENTER)
BV3
40FLOOR NO. 3 WIRE AND CONSOLE BOX WIRE (UNDER THE INSTRUMENT PANEL CENTER)
Bc140FLOOR NO 3 WIRE AND FLOOR WIRE (UNDER THE LEFT SIDE OF REAR SEAT CUSHION)Bc240FLOOR NO. 3 WIRE AND FLOOR WIRE (UNDER THE LEFT SIDE OF REAR SEAT CUSHION)
: GROUND POINTS
CODESEE PAGEGROUND POINTS LOCATION
II36UNDER THE ASHTRAY RH
BM40BACK PANEL CENTER
: SPLICE POINTS
CODESEE PAGEWIRE HARNESS WITH SPLICE POINTSCODESEE PAGEWIRE HARNESS WITH SPLICE POINTS
I3038CONSOLE BOX WIREB23
I3138CONSOLE BOX WIREB2440FLOOR NO. 3 WIRE
B16B25
40FLOOR NO. 3 WIRE
B1940FLOOR NO. 3 WIREB3540FLOOR MAIN WIRE
B22B3740FLOOR NO. 3 WIRE
SERVICE HINTS
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216
RADIO AND PLAYER (w/o CD PLAYER)
R 5(A) RADIO AND PLAYER
(A) 3±GROUND : APPROX. 12 VOLTS WITH IGNITION SW AT ACC OR ON POSITION
(A) 4±GROUND : ALWAYS APPROX. 12 VOLTS
(A) 7±GROUND : ALWAYS CONTINUITY
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
A1528R 3B29T16A31
A3230R 5C29T17B31
F1130R 6D29W 931
F1230R1231W1031
R 2A29R1331
: 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
1E20INSTRUMENT PANEL WIRE
: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS
CODESEE PAGEJOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)
IE136ENGINE ROOM MAIN WIRE AND COWL WIRE (R/B NO. 4)
IF236FRONT DOOR LH WIRE AND COWL WIRE (LEFT KICK PANEL)
IG236INSTRUMENT PANEL WIRE AND COWL WIRE (R/B NO. 5)
IP138FRONT DOOR RH WIRE AND COWL WIRE (RIGHT KICK PANEL)
IQ138INSTRUMENT PANEL WIRE AND CONSOLE BOX WIRE (UNDER THE INSTRUMENT PANEL CENTER)IQ238INSTRUMENT PANEL WIRE AND CONSOLE BOX WIRE (UNDER THE INSTRUMENT PANEL CENTER)
BT140FLOOR WIRE AND COWL WIRE (LEFT KICK PANEL)
BU140INSTRUMENT PANEL WIRE AND FLOOR 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 FLOOR WIRE (UNDER THE LEFT SIDE OF REAR SEAT CUSHION)Bc240FLOOR NO. 3 WIRE AND FLOOR WIRE (UNDER THE LEFT SIDE OF REAR SEAT CUSHION)
: GROUND POINTS
CODESEE PAGEGROUND POINTS LOCATION
II36UNDER THE ASHTRAY RH
BM40BACK PANEL CENTER
: SPLICE POINTS
CODESEE PAGEWIRE HARNESS WITH SPLICE POINTSCODESEE PAGEWIRE HARNESS WITH SPLICE POINTS
I3138CONSOLE BOX WIREB1940FLOOR NO. 3 WIRE
B1640FLOOR NO. 3 WIRE
SERVICE HINTS
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7XXX XX X
10 12 12
87 BA
N2
C22
A1 3
A12
A(
W/ MEMORY )
R16, R17
54B
R16, R17 (
W/O MEMORY ) 1
R
14 ,
R15
AB
193
DEFOGGER RELAY
2±4 : CLOSED WITH IGNITION SW AT ON POSITION AND DEFOGGER SW (A/C CONTROL ASSEMBLY) ON
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
A12B28R14A31R17A31
A13A28R15B31R17B31
C2230R16A31
N 227R16B31
: 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)
1A20ENGINE ROOM MAIN WIRE1B20ENGINE ROOM MAIN WIRE
1C20FLOOR WIRE
1D20FRONT DOOR LH WIRE
1E20INSTRUMENT PANEL WIRE
1H20COWL WIRE1J20COWL WIRE
3A22INSTRUMENT PANEL WIRE3G22INSTRUMENT PANEL WIRE
: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS
CODESEE PAGEJOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)
IE136ENGINE ROOM MAIN WIRE AND COWL WIRE (R/B NO. 4)
IG136INSTRUMENT PANEL WIRE AND COWL WIRE (R/B NO. 5)
IP138FRONT DOOR RH WIRE AND COWL WIRE (RIGHT KICK PANEL)
IQ138INSTRUMENT PANEL WIRE AND CONSOLE BOX WIRE (UNDER THE INSTRUMENT PANEL CENTER)
Bc240FLOOR NO. 3 WIRE AND FLOOR WIRE (UNDER THE LEFT SIDE OF REAR SEAT CUSHION)
: GROUND POINTS
CODESEE PAGEGROUND POINTS LOCATION
EB34FRONT SIDE OF LEFT FENDER
IF36LEFT KICK PANEL
IJ36RIGHT KICK PANEL
BL40UNDER THE CENTER PILLAR RH
: SPLICE POINTS
CODESEE PAGEWIRE HARNESS WITH SPLICE POINTSCODESEE PAGEWIRE HARNESS WITH SPLICE POINTS
E 934ENGINE ROOM MAIN WIRE
SERVICE HINTS
WhereEverybodyKnowsYourName

180
SRS AIRBAG
1G
10 1G 6
1G
11E 13
10 11
IK1
10 IK1 23
IK 1
1
4
+SL
5±SL
3+SR
2±SR
11D+
10D±
13E1
8E2
3E1
3E1
7
IG2 14
ACC 6
+B
12AB 4
TC 11
TC 5
AB
121212 7. 5A
IGN
15A
CIG 15A
ECU±B
FROM ENGINE AND
ECT ECU(
E1 )
CHECK
CONNECTOR
TDCL
FRONT AIRBAG
SENSOR LH FRONT A I RBA G
SENSOR RH
AIRBAG SQUIBSPIRAL
CA BLE
CENTER AIRBAG SENSOR ASSEMBLY
BR
W±B W±BL
Y B
GR
WR
L
Y
B
GR
WR
BR W±B
BR BR BR B±Y P±BP±B
B±Y
P±B
B±Y B±Y W±RW±R
L±R
B±O
FROM POWER SOURCE SYSTEM
(
SEE PAGE 56 )
AIRBA G WA RNING
LIGHT
[COMB. METER]
C10
F1 F2 A2 9 C3
T6 C12
E2 0
1G
9 912
IF ED 1G
7
EC
LA TC
1E
41E 3
3B
2
3H
12
3E
3
3E
10
1J
1 3A
3
1G
4
1G
3 3A
73D 11
B±Y
P±B
B±Y
P±B
B±Y
W±B
WhereEverybodyKnowsYourName

181
THE SRS (SUPPLEMENTAL RESTRAINT SYSTEM) AIRBAG IS A DRIVER PROTECTION DEVICE WHICH HAS A SUPPLEMENTAL ROLE
TO THE SEAT BELTS.
CURRENT FLOWS CONSTANTLY TO TERMINAL 6 OF THE CENTER AIRBAG SENSOR ASSEMBLY. WHEN THE IGNITION SW IS
TURNED TO ACC OR ON, CURRENT FROM THE CIG FUSE FLOWS TO TERMINAL 14 OF THE CENTER AIRBAG SENSOR ASSEMBLY.
ONLY WHEN THE IGNITION SW IS ON DOES THE CURRENT FROM THE IGN FUSE TO TERMINAL 7 .
IF AN ACCIDENT OCCURS WHILE DRIVING, DECELERATION CAUSED BY A FRONTAL IMPACT IS DETECTED BY EACH SENSOR AND
SWITCH, AND WHEN THE FRONTAL IMPACT EXCEEDS A SET LEVEL (WHEN THE SAFING SENSOR BUILT INTO THE CENTER AIRBAG
SENSOR ASSEMBLY IS ON AND THE CENTER AIRBAG SENSOR IS ON, FRONT AIRBAG SENSORS ARE OFF), CURRENT \
FROM THE
CIG OR IGN FUSE FLOWS TO TERMINAL 11 OF THE CENTER AIRBAG SENSOR ASSEMBLY " TERMINAL 1 OF THE AIRBAG SQUIB "
SQUIB " TERMINAL 2 " TERMINAL 10 OF CENTER AIRBAG SENSOR ASSEMBLY " TERMINAL 8, TERMINAL 13 OR BODY GROUND
" GROUND.
WHEN THE SAFING SENSOR BUILT INTO THE CENTER AIRBAG SENSOR ASSEMBLY IS ON AND THE FRONT AIRBAG SENSOR LH OR
RH IS ON, CENTER AIRBAG SENSOR IS OFF AND CURRENT FROM THE CIG OR IGN FUSE FLOWS TO TERMINAL 11 OF THE CENTER
AIRBAG SENSOR ASSEMBLY " TERMINAL 1 OF THE AIRBAG SQUIB " SQUIB " TERMINAL 2 " TERMINAL 10 OF CENTER AIRBAG
SENSOR ASSEMBLY " TERMINAL 3 OR 4 " TERMINAL 1 OF FRONT AIRBAG SENSOR " TERMINAL 2 " TERMINAL 2 OR 5 OF
CENTER AIRBAG SENSOR ASSEMBLY " TERMINAL 8, TERMINAL 13 OR BODY GROUND " GROUND , WHEN THE SAFING SENSOR
BUILT INTO THE CENTER AIRBAG SENSOR ASSEMBLY IS ON, AND THE FRONT AIRBAG SENSOR LH OR RH IS ON AND CENTER
AIRBAG SENSOR IS ON ONE OF THE ABOVE±MENTIONED CIRCUITS IS ACTIVATED SO THAT CURRENT FLOWS TO THE AIRBAG
SQUIB AND CAUSES IT TO OPERATE. THE BAG STORED INSIDE THE STEERING WHEEL PAD IS INSTANTANEOUSLY EXPANDED TO
SOFTEN THE SHOCK TO THE DRIVER.
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
A2928C1228T 629
C 326F 126
C1028F 226
: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR
CODESEE PAGEJUNCTION BLOCK AND WIRE HARNESS (CONNECTOR LOCATION)
1E20INSTRUMENT PANEL WIRE
1G20COWL NO. 2 WIRE
1J20COWL WIRE
3A
3B
3D22INSTRUMENT PANEL WIRE
3E
3H
: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS
CODESEE PAGEJOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)
IK136ENGINE WIRE AND INSTRUMENT PANEL WIRE (RIGHT KICK PANEL)
: GROUND POINTS
CODESEE PAGEGROUND POINTS LOCATION
EC34FRONT SIDE OF INTAKE MANIFOLD
ED34REAR SIDE OF CYLINDER HEAD RH
IF36LEFT KICK PANEL
: SPLICE POINTS
CODESEE PAGEWIRE HARNESS WITH SPLICE POINTSCODESEE PAGEWIRE HARNESS WITH SPLICE POINTS
E2034ENGINE WIRE
SYSTEM OUTLINE
WhereEverybodyKnowsYourName

63
E18E14
E20
2 1
ED
W± L
B
B±O
B
W± B B±OB±O
B±O
BB
B± O
TO COMBINATION
METER
(
TACHO )12
DISTRIBTOR
IGNITION COIL
I4
D13
IG± TAC +B
IGF IGT C±
IGNITER
CHECK
CONNECTOR
C3 I2
435
19
12
STA IGF IGT
77 58 57
ENGINE AND ECT ECU (
A/T )
E10
NOISE FILTER
(
FOR IGNITION SYSTEM )
N31234
27 26 25 7 NE G1 G2 G± NE G1 G2 G±
L
R Y
B
W±Y
R±Y
ENGINE ECU
(
M/T )
E12
WhereEverybodyKnowsYourName

64
STARTING AND IGNITION
C 4 COLD START INJECTOR
2±1 : APPROX. 12 VOLTS WHILE START INJECTOR TIME SW IS CLOSED AND STARTER CRANKING
I15 IGNITION SW
4±1 : CLOSED WITH IGNITION SW AT ST POSITION
11±6: CLOSED WITH IGNITION SW AT ON OR ST POSITION
N 1 NEUTRAL START SW
3±2 : CLOSED WITH A/T SHIFT LEVER IN P OR N POSITION
S 6(B), S 7(A) STARTER
POINTS CLOSED WITH NEUTRAL START SW ON AND IGNITION SW AT ST POSITION
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
C 326F 926N 327
C2328I 227S 6B27
D1326I 427S 7A27
E1028I1529
E1228N 127
: 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)
1B20ENGINE ROOM MAIN WIRE
1J20COWL WIRE1K20COWL WIRE
: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS
CODESEE PAGEJOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)
EB134ENGINE WIRE AND ENGINE ROOM MAIN WIRE (FRONT SIDE OF R/B NO 2)EB234ENGINE WIRE AND ENGINE ROOM MAIN WIRE (FRONT SIDE OF R/B NO. 2)
IE136ENGINE ROOM MAIN WIRE AND COWL WIRE (R/B NO. 4)
IJ136ENGINE WIRE AND COWL WIRE (RIGHT KICK PANEL)
IJ236ENGINE WIRE AND COWL WIRE (RIGHT KICK PANEL)
: GROUND POINTS
CODESEE PAGEGROUND POINTS LOCATION
ED34REAR SIDE OF INTAKE MANIFOLD
: SPLICE POINTS
CODESEE PAGEWIRE HARNESS WITH SPLICE POINTSCODESEE PAGEWIRE HARNESS WITH SPLICE POINTS
E1434ENGINE WIREE1934ENGINE WIREE1834ENGINE WIREE2034ENGINE WIRE
SERVICE HINTS
WhereEverybodyKnowsYourName

88
TAILLIGHT
WHEN THE LIGHT CONTROL SW IS TURNED TO TAIL OR HEAD POSITION. THE CURRENT FLOWS TO TERMINAL 3 OF THE LIGHT
FAILURE SENSOR THROUGH THE TAIL FUSE.
WHEN THE IGNITION SW IS TURNED ON, THE CURRENT FLOWS FROM THE GAUGE FUSE TO TERMINAL 8 OF THE LIGHT FAILURE
SENSOR, AND ALSO FLOWS THROUGH THE REAR LIGHT WARNING LIGHT TO TERMINAL 4 OF THE LIGHT FAILURE SENSOR.
TAILLIGHT DISCONNECTION WARNING
WITH THE IGNITION SW ON AND THE LIGHT CONTROL SW TURNED TO TAIL OR HEAD POSITION. IF THE TAILLIGHT CIRCUIT IS
OPEN, THE LIGHT FAILURE SENSOR DETECTS THE FAILURE BY THE CHANGE IN CURRENT FLOWING FROM TERMINAL 3 OF THE
LIGHT FAILURE SENSOR TO TERMINAL 9, 11 AND THE WARNING CIRCUIT OF THE LIGHT FAILURE SENSOR IS ACTIVATED.
AS A RESULT, THE CURRENT FLOWS FROM TERMINAL 4 OF THE LIGHT FAILURE SENSOR " TERMINAL 11 " GROUND AND TURNS
THE REAR LIGHT WARNING LIGHT ON, WHICH REMAINS ON UNTIL THE LIGHT CONTROL SW IS TURNED O\
FF.
TAILLIGHT RELAY
5±3 : CLOSED WITH LIGHT CONTROL SW AT TAIL OR HEAD POSITION
L 3 LIGHT FAILURE SENSOR
4, 8±GROUND : APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION
3±GROUND : APPROX. 12 VOLTS WITH LIGHT CONTROL SW AT TAIL OR HEAD POSITION
11±GROUND : ALWAYS CONTINUITY
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
C13B28F 526L 230
C14A28F 626L 330
C1528F 926R1031
F 326I16A29 (USA)R1131
F 426I16B29 (CANADA)
: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR
CODESEE PAGEJUNCTION BLOCK AND WIRE HARNESS (CONNECTOR LOCATION)
1A20ENGINE ROOM MAIN WIRE1B20ENGINE ROOM MAIN WIRE
1C20FLOOR WIRE
1E20INSTRUMENT PANEL WIRE
1J20COWL WIRE1K20COWL WIRE
3A22INSTRUMENT PANEL WIRE3D22INSTRUMENT PANEL WIRE
: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS
CODESEE PAGEJOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)
BU140FLOOR WIRE AND INSTRUMENT PANEL WIRE (LEFT KICK PANEL)
: GROUND POINTS
CODESEE PAGEGROUND POINTS LOCATION
EA34FRONT SIDE OF RIGHT FENDER
IF36LEFT KICK PANEL
BM40BACK PANEL CENTER
: SPLICE POINTS
CODESEE PAGEWIRE HARNESS WITH SPLICE POINTSCODESEE PAGEWIRE HARNESS WITH SPLICE POINTS
E 1E1134ENGINE ROOM MAIN WIRE
E 434ENGINE ROOM MAIN WIREB1440FLOOR MAIN WIREE 534ENGINE ROOM MAIN WIREB1540FLOOR MAIN WIRE
SYSTEM OUTLINE
SERVICE HINTS
WhereEverybodyKnowsYourName