LEXUS SC400 1991 Service Repair Manual

147
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
A 4B26A3130D 228
A 726A33A26F 926
A 826B 126P 329
A22A28C 326S1229
A23B28C13B28T 629
A3030C14A28
: RELAY BLOCKS
CODESEE PAGERELAY BLOCKS (RELAY BLOCK LOCATION)
219ENGINE COMPARTMENT LEFT624ENGINE COMPARTMENT LEFT
: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR
CODESEE PAGEJUNCTION BLOCK AND WIRE HARNESS (CONNECTOR LOCATION)
1E20INSTRUMENT PANEL WIRE
1H20COWL WIRE1I20COWL WIRE
3A
3D22INSTRUMENT PANEL WIRE3E22INSTRUMENT PANEL WIRE
3H
: 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)
IE136ENGINE ROOM MAIN WIRE AND COWL WIRE (R/B NO. 4)
IE238ENGINE ROOM MAIN WIRE AND COWL WIRE (BEHIND GLOVE BOX)
IG136INSTRUMENT PANEL WIRE AND COWL WIRE (R/B NO. 5)
IK136ENGINE WIRE AND INSTRUMENT PANEL WIRE (RIGHT KICK PANEL)IK236ENGINE WIRE AND INSTRUMENT PANEL WIRE (RIGHT KICK PANEL)
IO138ENGINE ROOM MAIN WIRE AND INSTRUMENT PANEL WIRE (RIGHT KICK PANEL)
BW140ENGINE ROOM MAIN WIRE AND FLOOR NO. 3 WIRE (RIGHT KICK PANEL)
Bc240FLOOR NO. 3 WIRE AND FLOOR WIRE (UNDER THE LEFT SIDE OF REAR SEAT CUSHION)
: GROUND POINTS
CODESEE PAGEGROUND POINTS LOCATION
EA34FRONT SIDE OF RIGHT FENDER
EB34FRONT SIDE OF LEFT FENDER
IJ36RIGHT KICK PANEL
: SPLICE POINTS
CODESEE PAGEWIRE HARNESS WITH SPLICE POINTSCODESEE PAGEWIRE HARNESS WITH SPLICE POINTS
E 934ENGINE ROOM MAIN WIREI2638ENGINE ROOM MAIN WIRE
E1034ENGINE ROOM MAIN WIREB1740FLOOR NO. 3 WIRE
E1234ENGINE ROOM MAIN WIREB3440FLOOR MAIN WIRE
I2338INSTRUMENT PANEL WIREB3640FLOOR NO. 3 WIRE
I2538ENGINE ROOM MAIN WIRE
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134
ABS AND TRACTION CONTROL
34
3 2
16
1
4
26
666
66
66
6 56
ABS MOTOR
RELAY
ABS ACTUATOR
RELAY4 1
3
26
6
66TRACTION MOTOR
RE LA Y
M
A
13 SFL C
12 SRL
A
8 AST
A
7 MT
B
1 SFR
B
4B 51B 2B3
A 2
A 1
C 1
L±W
L
Y
B±Y
P±B
L±W Y±G
SFR SFL SRL AST MT
BS
BM
GND
ABS ACTUATOR A4,A5 ,A6 B
B C
A
EA
EB B
16
MR A
9
TMR
A
22
SR
A
25
R± E10
E12
6
11 2
L±Y
W±B V±Y
W±B B±R
R
Y R
W±B V±Y
W±B W±B
W±B
Y
V±Y
R±B G Y
R R
W±B L±W
V±Y
V±Y
G V±Y
L
L±W
L
W±B W±B W±B W
R Y
30A ABS NO. 2
60A ABS NO. 1 120A ALT
BATTERY
FUSE BLOCK
ABS AND TRACTION ECUA
26 SRR
6
P
SRR B
A24
,A25 ,
A26
F9
B
A
B
A
5 FL+
A
18 FL ±
21 (
SHIELDED )
W
B
B
W
A7
FRONT LH
E2
V±Y
W±B
V±Y
R±B
V±Y
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135
B
4 RL+
B
15 RL±
B
5 RSS
B
14 RR+
B
3 ALT
BW1
3BW1 8
BW1
2
BW1
5
BW1
6
Bc2
6
Bc2
2 I26
12 12
W O W±B
L±G
L±Y
W
O
L±G L±Y
W
O
L±G L±Y
(
SHIELDED ) (
SHIELDED )
(
SHIELDED )
REAR LH REAR RH A3 1
A3 0
ABS SPEED SENSOR
M
6
1
4
36
6
66
TRACTION BRAKE
MAIN RELAY
2 16 22
3
1 23 11
E7
I25 I32
I23
EB1
6
IO1
7 IK2
2
A
23
MTT A
1
TSR A
20
E2 A
19
VC A
10
PR A
15
SRC A
2
SMC A
12
SAC C
1
TS B
9
WA C
3
TC
A
1A 2A3
A
4A 5A6
B
2
B
1 B
4
L±Y
B±R
L
L
L
L VB±R
P±B
P±B B±R
R±W
R±W
R±W
W
R
B
V±Y V
V±W B±R
R
R±W
V±Y
TS WA
R
B±R
L±Y
W±B V±Y
W±B W±B P±B
L
TC
WB
T5 T3
,
T4C3
TRACTION PUMP
AND MOTOR TRACTI ON BRA KE
ACTUATOR
CHECK
CONNECTOR
BA
(
SHIELDED )
C
ABS AND TRACTION ECU A24 ,
A25 ,A26
AB P±B
P±B
ACC CUT MIC CUT
RESERVOIR
CUT
(
SHIELDED )
A
17 FR+
A
4 FR±
A
16 FS S
I26
21(
SHIELDED )
O±L
W±L W±B
W±L O±L
A8
FRONT RH B
8
IO1
10
3B
1
3B
2
IJ 1
5 IG3
1
A1 0
ALTERNATOR Y±G
Y±G
Y±G
Y±G
Y±G
RR±
I26
B17
BR
BR
I26
B34
BW1
7
Bc2
5 B17
B36
BR±B BR±B BR±B
BR±B
(
SHIELDED )
2
SHORT
PIN
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136
ABS AND TRACTION CONTROL
I16E9
I14
I25 I25
I4
E13 I7
1E
12 1I 10 2 1I 8
14 8 17 4
IO1
8
IK2
9 3E
3
A1
B
15 B 5B1
B
22 GND1
B
2 GND2
B
13 GND3
B
6 LBL
B
17 PKB C
7 ABSO
C
12 BRP
C
8 BRC
C
7 THFA
C
11 BRFA
C
15 FRO
C
6 FL O
C
10 P
C
5 N
B
20
D/G B
10
STP B
21
BATT A
24
IG
3A
4
3D13
IK25 IO1
1IE2 7
1 2
I7 1H1
1E20
FROM POWER SOURCE SYSTEM
(
SEE PAGE 56 )
2 1 2 1
2 1 1
EA
IJ IG1
19 IG1 20IK2
18
IE2
12 IE1
1 IO1
9
P±B
Y
W
G±W
G±W
R
B±R
B±R R
G±W
Y
LG±R W
L V±W
L±Y W
G±W B±R
R±B
R±B
L
GR LG
LG±B P±L
P±G
V±R
B±Y
W±B
W±B
W±B
R±W
R±W
R±W
R±W
B
R±W
R±W
R±WR±B
B
W±B W±B W±B
V±W
L±Y
L
P±B
R±W R±W
B WW
R±W
10A
GAUGE
15A
STOP10A
DOME15A
ECU±IG
WTRC
ABS TC
G±W
COMBINATION METER STOP LIGHT
SW
TDCL
ABS AND TRACTION ECU
B
B
PARKING
BRAKE SW
BRAKE FLUID
LEVEL SW
DIODE
(FOR BRAKE FLUID LEVEL )
DIODE
( FOR P ARK I NG
BRAKE ) (
CANADA )
(
USA )
A24
,A2 5
,A26
C13
,
C14
T6 S12
P3
B1 D1
D2
B
A
B B±R
R
G± W
LG±R W
L±Y
B±Y
V±R
P±G P±L
LG±B LG
GR L
R±B
R±W
IK 1
10
3H
12
P±B
TRAC OFF TRAC ANTI
LOCK
A
B 2
1
P±B
P±B
P±B
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137
B±RR
G±W
LG±R W
L±Y
B±Y
V±R
P±G P±L
LG±B LG
GR L
R±B
R±W TRACTION E CUE9 , E10
AB
I33
I36 I36 2
IK2
15 EB1 5
1B
5
3A6
B
11
IND B
14
WT B
8
BAT B
2
STP
A
16
TR5 A
2
IG A
15
BM A
21
TR2 A
6
NEO A
8
VTH A
19
VSH
A
4 TRCO
A
5 THFA A
4 W
A
37 TR
A
38 NEO
A
40 VT01
A
39 VT02
B
6 TC
B
1 BRC
B
4 BRFA
B
10 FRO
B
3 FL O
B
7 P
B
16 N
B
15 ABSO
B
5 RLO
A
1 PKB
C
13 RRO
C
4 RLO
C
14 TRCO 1E
11
3B3
IJ2 12
IK2 4 IJ2
7
IK112
IK1 13 A
23 BRP
L±R
L±Y
Y±R P±L
V±Y Y±L
L±Y
W
LG±R
B±R R
G±W L±R
Y±R P±L
V±Y Y±L
P
R±W B±Y
V±R
P±G P±L
LG±B
LG
GR L
R±B
R±W P
R±W
L±YR
L±R
GRLG± R L
Y±B
LG±R
G±W
B±R
RR FROM POWER SOURCE SYSTEM
(
SEE PAGE 56 )
7. 5A
TRAC
GR L
FROM A/T INDICATOR SW ENGINE AND ECT ECU
T1 3 ,T14
BA 13 14
I33 A
6
STP
G±W
G±W
B
12 RRO
P±B
P±B
IK2
13
3H
7
3F
2
R±W R±W
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138
ABS AND TRACTION CONTROL*1 : USA SPEC.
B
41 VC
B
43 VTA
B
64 IDL
B
46 THG
B
63 IDL2
B
44 THW
B
69 E1
A
26 BCM
A
25 B
A
24 B
A
11 A
A
12 A
A
13 ACM
A
14 GN D
A
20 E1
B
13 CSWA
10
IDL1 A
22
IDL2
1
2
3
4
VC VTA IDL E2 1
2
3
4
VC VTA IDL E2
E18
I32
E18
I37 I32
6 2
IF IJ ED
3H
14
1E
18 3A
1
1J
1 213645 BR
L±R RR±B
BR
BR
BRG
R±B R
Y
L±R
R±B R
BR
BR
R±B
Y±L BR
RY
L±R
Y
R L
W G
BR
W±B
BR
W±B
BR W±B
W±B
W±B
B+ B± B A A± A+
L±R
TO AI R FL OW
METER
(
VC )
FROM AIR FLOW
METER(
E2 )
THROTTLE POSITION
SENSOR SUBTHROTTLEPOSITION
SENSOR
IK2
16
Y±R
Y±R
S UB THROTTLE A CTUATOR
TRACTION
CUT SW TRACTION ECU
T12
S8
T1 3 , T 1 4
A B S9
T2 ENGINE AND ECT ECU E9
,E10
B A
IJ1
13
W±B (
SHIELDED )
E20 B
65 E2
BR
I32
B
42 VTA2
Y±LBR
1 2
1
2
BRE3
EGR GAS TEMP
SENSOR
EFI WATER
TEMP. SENSOR
A
3 S1
BR (
*1 )
(
*1 )
E2
±±
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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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140
ABS AND TRACTION CONTROL
A24(A), A25(B), A26(C) ABS AND TRACTION ECU
(B) 21±GROUND : ALWAYS APPROX. 12 VOLTS
(B) 11±GROUND : APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION
(B) 10±GROUND : CONTINUITY WITH STOP LIGHT SW ON
(B) 2, (B) 13, (B) 22±GROUND : ALWAYS CONTINUITY
(B) 17±GROUND : CONTINUITY WITH PARKING BRAKE LEVER PULLED UP (PARKING BRAKE SW ON)
A 4(B), A 5(C), A 6(A) ABS ACTUATOR
(A) 1, (A) 2±GROUND : APPROX. APPROX. 12 VOLTS
(C) 1±GROUND : ALWAYS CONTINUITY
(B) 1, (B) 5, (B) 4, (B) 6±GROUND : APPROX. 1.15 (IGNITION SW OFF)
(B) 2±GROUND : APPROX. 5 (IGNITION SW OFF)
T3(A), T 4(B) TRACTION BRAKE ACTUATOR
(B) 2± (B) 4 : OPEN ABOVE APPROX. 134.5KG/CM2
(13189 KPA, 1910PSI)
CLOSED BELOW APPROX. 95KG/CM2 (9316 KPA, 1349PSI)
(A) 3± (A) 6 : APPROX. 2
(A) 2± (A) 5 : APPROX. 2
(A) 1± (A) 4 : APPROX. 2
S12 STOP LIGHT SW
2±1 : CLOSED WITH BRAKE PEDAL DEPRESSED
A 7, A 8, A30, A31 ABS SPEED SENSOR FRONT LH, RH, REAR LH, RH
1±2 : APPROX. 1.0(20 °C, 68°F)
T13(B), T14(A) TRACTION ECU
(A) 2±GROUND : APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION
(A) 15±GROUND : ALWAYS APPROX. 12 VOLTS
(A) 20, (A)14±GROUND : ALWAYS CONTINUITY
(A) 1±GROUND : CONTINUITY WITH PARKING BRAKE LEVER PULLED UP
(B) 2±GROUND : APPROX. 12 VOLTS WITH STOP LIGHT SW ON
(B) 13±GROUND : CONTINUITY WITH TRACTION CUT SW PUSHED ON
(B) 8±GROUND : ALWAYS APPROX. 12 VOLTS
P 3 PARKING BRAKE SW
1±GROUND : CLOSED WITH PARKING BRAKE LEVER PULLED UP
S 8 SUB THROTTLE ACTUATOR
2±1, 2±3 : APPROX. 0.9
5±4, 5±6 : APPROX. 0.9
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
A 4B26C 326S 927
A 5C26C13B28S1229
A 6A26C14A28T 227
A 726D 128T 3A27
A 826D 228T 4B27
A1026E 226T 527
A24A28E 326T 629
A25B28E 9A28T1229
A26C28E10B28T13B29
A3030F 926T14A29
A3130P 329
B 126S 827
: RELAY BLOCKS
CODESEE PAGERELAY BLOCKS (RELAY BLOCK LOCATION)
219ENGINE COMPARTMENT LEFT624ENGINE COMPARTMENT LEFT
SERVICE HINTS
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141
: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR
CODESEE PAGEJUNCTION BLOCK AND WIRE HARNESS (CONNECTOR LOCATION)1B20ENGINE ROOM MAIN WIRE1E20INSTRUMENT PANEL WIRE1H1I20COWL WIRE1J20COWL WIRE
3A3B3D22INSTRUMENT PANEL WIRE3E22INSTRUMENT PANEL WIRE
3F3H
: 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)IE136ENGINE ROOM MAIN WIRE AND COWL WIRE (R/B NO. 4)IE236ENGINE ROOM MAIN WIRE AND COWL WIRE (BEHIND GLOVE BOX)IG136INSTRUMENT PANEL WIRE AND COWL WIRE (R/B NO. 5)IG336INSTRUMENT PANEL WIRE AND COWL WIRE (RIGHT KICK PANEL)IJ136ENGINE WIRE AND COWL WIRE (RIGHT KICK PANEL)IJ236ENGINE WIRE AND COWL WIRE (RIGHT KICK PANEL)
IK136ENGINE WIRE AND INSTRUMENT PANEL WIRE (RIGHT KICK PANEL)IK236ENGINE WIRE AND INSTRUMENT PANEL WIRE (RIGHT KICK PANEL)
IO138ENGINE ROOM MAIN WIRE AND INSTRUMENT PANEL WIRE (RIGHT KICK PANEL)BW140ENGINE ROOM MAIN WIRE AND FLOOR NO. 3 WIRE (RIGHT KICK PANEL)Bc240FLOOR NO. 3 WIRE AND FLOOR WIRE (UNDER THE LEFT SIDE OF REAR SEAT CUSHION)
: GROUND POINTS
CODESEE PAGEGROUND POINTS LOCATIONEA34FRONT SIDE OF RIGHT FENDEREB34FRONT SIDE OF LEFT FENDERED34REAR SIDE OF INTAKE MANIFOLDIF36LEFT KICK PANELIJ36RIGHT KICK PANEL
: SPLICE POINTS
CODESEE PAGEWIRE HARNESS WITH SPLICE POINTSCODESEE PAGEWIRE HARNESS WITH SPLICE POINTSE 2I2338INSTRUMENT PANEL WIREE 7I2538ENGINE ROOM MAIN WIREE 934ENGINE ROOM MAIN WIRE
ENGINE ROOM MAIN WIREI2638ENGINE ROOM MAIN WIRE
E1034ENGINE ROOM MAIN WIRE
ENGINE ROOM MAIN WIREI32E12I33E13I3538ENGINE WIREE1834ENGINE WIREI3638ENGINE WIRE
E2034ENGINE WIREI37I 4B1740FLOOR NO. 3 WIREI 738COWL WIREB3440FLOOR MAIN WIREI1438COWL WIREB3640FLOOR NO. 3 WIREI1638INSTRUMENT PANEL WIRE
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142
ABS AND TRACTION CONTROL
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