LEXUS SC400 1991 Service Repair Manual

152
CRUISE CONTROL
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
C 326C1928P 329
C 826C2328S1229
C12B28C2428T 629
C14A28E 9A28
C1528E10B28
: 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
1E20INSTRUMENT PANEL WIRE
1H
1I20COWL WIRE
1K
20COWL WIRE
3A
3C
3D22INSTRUMENT PANEL WIRE3E22INSTRUMENT PANEL WIRE
3F
3H
: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS
CODESEE PAGEJOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)
IE236ENGINE ROOM MAIN WIRE AND COWL WIRE (BEHIND GLOVE BOX)
IG136INSTRUMENT PANEL WIRE AND COWL WIRE (R/B NO. 5)
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)
: GROUND POINTS
CODESEE PAGEGROUND POINTS LOCATION
EA34FRONT SIDE OF RIGHT FENDER
IG36INSTRUMENT PANEL BRACE LH
IH36UNDER THE ASHTRAY LH
: SPLICE POINTS
CODESEE PAGEWIRE HARNESS WITH SPLICE POINTSCODESEE PAGEWIRE HARNESS WITH SPLICE POINTS
I 738COWL WIREI 938COWL WIRE
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ECT AND A/T INDICATOR
21I
5
22 EB1 8 EB14
A
24 A 33 A 12 A1
A
32 A 31 B 10 B8
22
EB2
3
I33 IJ2
11
EB B±Y
B±O
B±R
B±Y
B±O B±Y
B±O
W±B
B±R
B±Y
BR±Y B±O B±O
B±R
B±R
LG
R±L
B±R
W±B
FROM POWER SOURCE SYSTEM (
SEE PAGE 56 )
30A
EFI
3
13
WY
M±REL BATT OD1 IGSW +B1 +B S1 S3
FROM
CRUISE CONTROL ECU (
OD )
7. 5A
IGN
21
43
ENGINE AND ECT ECU
ECT SOLENOID
E9
,E10
B
A
NO. 1
NO. 3
EFI
MAIN
RELAY 4
B
9
W±R
2
B
S2
NO. 2
E1
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127
2 1
2
1
E18 E20
E20 I32
I32
B
27 B
4B 28 A20 B 29
B
42 B 63 B 41 B43 B64 B65 B 44 B 23 B3
ED
E18
L±R
Y±L
R±B
BR
L±R Y
R BR
BR
Y±L
R±B
L±R Y
R
BR
G
P
V
GR±Y LG
B±Y BR
LG
BR
W±B
BR L
LG
GR±Y
BR
L±R
GR±Y
14 8 13
3
NE
E11 VF2 TE1 VF1
VTA2 IDL2 VC VTA1 IDL1 E2 THW SP2 SP2±
G1 TVF1
E1
SUBTHROTTLEPOSITION
SENSOR
(
W/ TRACTION CONTROL ) THROTTLE POSITION SENSOR
EFI WATER
TEMP. SENSOR
SPEED SENSOR
NO. 2(
FOR ECT )
ENGINE AND ECT ECU
CHE CK CONNE CTOR
VC VTA IDL2 E2 VC VTA IDL E2
4321 4321
C3
S4
E2
T2
S9
B
E9
,E10
A
P
(
W/ TRACTION CONTROL )
( W/ TRACTION CONTROL )
( W/ TRACTION CONTROL )
( W/ TRACTION
CONTROL )
BR
B
26
R
G1
B
25
Y
G2
B
7
B
G±
VF2
NE
G±
G2 B
79
W±B
EO2
B
80
W±B
EO1
I33 I33 B
69
BR
E1
W±B W±B
2341
D13
DISTRIBUTOR
BR
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128
ECT AND A/T INDICATOR
POWER NORMAL
3 4
71529 1 2 IJ 2
3
IK1
5IK1 2IK1 22
IJ 1
6
IK1
21
IG2
7
1E
12
1K
4
3D
3
3D
63B 43B
53D
3A
4
3D13 1H
12
B
76
NSW A
18
P A
9
2 A
10
L A
2
SP1
B
17 TT
A
19 TE2
A
28 OD2
IK 1 4
IK 1 3 I19
A
14
IJ1
10
GR±Y LG G±O G±O Y
Y
G
W
G±O
GR±R W±B
Y
Y
Y
ENG TE1 TT TE2 ECT
Y
Y B±W
B±W
G±O
G
W
P
P
P
P G±R
G±Y
GR±R
GR±R
GR±Y
LG
G±R G±Y
GR±R
W±B GR±R GR±R G±O
FROM POWER SOURCE SYSTEM
(
SEE PAGE 56 )
5
7. 5A
ST
10A
GAUGE
ECT PATTERN
SELECT SW
ENGINE AND ECT ECU
O/D MAIN
SW
TDCL E8
E9 , E1 0
T6
O5
A A
10IH
BR
A
E20
IK1
6
IK1
7
2
2 A
13
A
15
SHORT
CONNE CTOR
L±R L±R
R
32
OU T GND
L±R
R
1
VCC SPEED SENSOR
NO. 1 S3
Y
A
B
B
S22 A
,S23
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129
PRND 2 1146578 9
GR
R±B
L
G±W G
W
A/T INDICATOR SW
[NEUTRAL START SW AND BA CK ±UP LIGHT SW]
N1
B
4C 1C 2C3C4C 5C16 A 1
410
56789
I33
I33
I19
I19
I19
I19
I22
I22
IK 1
12 IK1 11 IK113 IK1 14 IK116 IK117
C
18
B A
23
3D10
3D 9 3H
3
3A 1
1J1
1E 18
IF
Y
Y
G
W
G±O
GR±R W±B W±B
W±B W±B
GR±R Y
G
W
W
G
G±W L
R±B
GR
G±O
GR
R±B
L
G±W G
W
Y
GR
R±B
L
G±W G
W
W±B
W±BA/T INDICATOR LIGHT
[COMB. METER]
ECT POWER P
R
N
D
2
L
O/D OFF
A/T INDICATOR LIGHT
( FOR SHIFT LEVER )
A2 1
C12 ,C13
,C14A
W±B
C PRND2 L
W
G
G±W
L
R±B
GR
C
17 3H
1 3A
9
TO P ANE L FUS E (
USA )
TO I NTE GRA TI ON REL AY (
CA NA DA )
1
G±O
3C1
G±O
G±O
G±O
G±O G±O
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130
ECT AND A/T INDICATOR
THIS SYSTEM, ELECTRICALLY CONTROLS THE LINE PRESSURE, THROTTLE PRESSURE, LOCK±UP PRESSURE AND\
ACCUMULATOR
PRESSURE ETC. THROUGH THE SOLENOID VALVE. THE ECT IS A SYSTEM WHICH PRECISELY CONTROLS GEAR SHIFT TIMING AND
LOCK±UP TIMING IN RESPONSE TO THE VEHICLE'S DRIVING CONDITIONS AND THE ENGINE OPERATING CONDITIONS DETECTED
BY VARIOUS SENSORS, MAKING SMOOTH DRIVING POSSIBLE BY SHIFT SELECTION FOR EA\
CH GEAR WHICH IS THE MOST
APPROPRIATE TO THE DRIVING CONDITIONS AT THAT TIME, AND CONTROLS THE ENGINE TORQUE DURING SHIFTING TO ACHIEVE
OPTIMUM SHIFT FEELING.
1. GEAR SHIFT OPERATION
WHEN DRIVING, THE ENGINE WARM UP CONDITION IS INPUT AS A SIGNAL TO TERMINAL (B)44 OF THE ECU FROM THE EFI WATER
TEMP. SENSOR AND THE VEHICLE SPEED SIGNAL FROM SPEED SENSOR NO.2 IS INPUT TO TERMINAL (B)23 OF THE ECU. AT THE
SAME TIME, THE THROTTLE VALVE OPENING SIGNAL FROM THE THROTTLE POSITION SENSOR (MAIN) IS INPUT TO TERMINAL
(B)43 OF THE ECU AS ENGINE RPM CONDITION (IDLING, HIGH LOAD AND ACCELERATION CONDITIONS) SIGNAL.
BASED ON THESE SIGNALS, THE ECU SELECTS THE BEST SHIFT POSITION FOR DRIVING C\
ONDITIONS AND SENDS CURRENT TO
THE ECT SOLENOIDS.
WHEN SHIFTING TO 1ST SPEED, THE CURRENT FLOWS FROM TERMINAL (B)10 OF THE ECU " TERMINAL 1 OF ECT SOLENOIDS "
GROUND AND CONTINUITY TO NO.1 SOLENOID CAUSES THE SHIFT (NO.2 SOLENOID DOES NOT HAVE CONTINUITY AT THIS TIME).
FOR 2ND SPEED, THE CURRENT FLOWS SIMULTANEOUSLY FROM TERMINAL (B)9 OF THE ECU " TERMINAL 2 OF ECT SOLENOIDS
" GROUND, AND FROM TERMINAL (B)10 OF THE ECU " TERMINAL 1 OF ECT SOLENOIDS " GROUND, AND CONTINUITY TO NO.1
AND NO.2 SOLENOIDS CAUSES THE SHIFT.
FOR 3RD SPEED, THERE IS NO CONTINUITY TO NO.1 SOLENOID, ONLY TO NO.2 SOLENOID, CAUSING THE SHIFT.
SHIFTING INTO THE 4TH SPEED (OVERDRIVE) OCCURS WHEN NO CURRENT FLOWS TO NO.1 AND NO.2 SOLENOIDS. THE NO.4
SOLENOID (FOR ACCUMULATOR BACK PRESSURE MODULATION) IS INSTALLED TO ADJUST THE BACK PRESSURE ON THE
ACCUMULATOR AND CONTROL THE HYDRAULIC PRESSURE DURING SHIFTING AND LOCK±UP IN \
ORDER TO PROVIDE SMOOTH
SHIFTING WITH LITTLE SHIFT SHOCK.
2. LOCK±UP OPERATION
WHEN THE ECT ECU DECIDES, BASED ON EACH SIGNAL, THAT THE LOCK±UP CONDITION HAS BEEN MET, THE CURRENT FLOWS
FROM " TERMINAL (B)8 OF THE ECU " TERMINAL 3 OF THE ECT SOLENOID " GROUND, CAUSING CONTINUITY TO THE LOCK±UP
SOLENOID AND CAUSING LOCK±UP OPERATION.
3. STOP LIGHT SW CIRCUIT
IF THE BRAKE PEDAL IS DEPRESSED (STOP LIGHT SW ON) WHEN DRIVING IN LOCK±UP CONDITION, A SIGNAL IS INPUT\
TO
TERMINAL (A)4 OF THE ECU. THE ECU OPERATES AND CUTS THE CURRENT TO THE SOLENOID TO RELEASE LOCK±UP.
4. OVERDRIVE CIRCUIT
*O/D MAIN SW ON
WHEN THE O/D MAIN SW IS TURNED ON (SW POINT IS OPEN), A SIGNAL IS INPU\
T TO TERMINAL (A)28 OF THE ECU AND THE ECT
CAUSES SHIFT TO OVERDRIVE WHEN THE CONDITIONS FOR OVERDRIVE ARE MET.
* O/D MAIN SW OFF
WHEN THE O/D MAIN SW IS TURNED OFF (SW POINT IS CLOSED), THE CURRENT FLOWI\
NG THROUGH THE O/D OFF INDICATOR
LIGHT FLOWS TO GROUND BY WAY OF THE O/D MAIN SW AND CAUSES THE O/D OFF INDICATOR LIGHT TO LIGHT UP. AT THE
SAME TIME, A SIGNAL IS INPUT TO TERMINAL (A)28 OF THE ECU AND THE ECT PREVENTS SHIFT INTO OVERDRIVE.
5. ECT PATTERN SELECT SW CIRCUIT
WHEN THE ECT PATTERN SELECT SW IS CHANGED FROM ªNORMALº TO ªPOWERº, THE CURRENT THROUGH THE GAUGE FUSE
FLOWS TO TERMINAL 4 OF ECT PATTERN SELECT SW " TERMINAL 3 " TERMINAL (B)4 OF A/T INDICATOR " TERMINAL (C)23 "
GROUND AND CAUSES THE INDICATOR LIGHT TO LIGHT UP. AT THE SAME TIME, THE CURRENT FLOWS TO TERMINAL (A)18 OF
THE ECU AND THE ECU PERFORMS SHIFT UP AND SHIFT DOWN AT A HIGHER VEHICLE SPEED RANGE COMPARED WITH
ªNORMALº POSITION.
6. KICK DOWN OPERATION
WHEN THE ACCELERATOR IS DEPRESSED FURTHER THAN THE FULL THROTTLE POSITION WHILE DRIVING, THE KICK DOWN SW
TURNS ON AND ITS SIGNAL IS INPUT TO TERMINAL (A)3 OF THE ECU. THEN, THE ECU CONTROLS THE CURRENT WHICH FLOWS
FROM TERMINALS (B)10 AND (B)9 OF THE ECU TO THE NO. 1 AND NO. 2 SOLENOIDS AND SHIFTS DOWN BY TURNING THE
SOLENOIDS ON AND OFF.
7. CRUISE CONTROL
WHEN CRUISE CONTROL OPERATION IS SELECTED A SIGNAL IS INPUT TO TERMINAL (A)12 OF THE ECU FROM CRUISE CONTROL
ECU. AS A RESULT, THE ECU OPERATES AND CONTROLS OVERDRIVE, LOCK±UP AND SO ON FOR SMOOTH DRIVING.
SYSTEM OUTLINE
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131
E 1 ECT SOLENOID
1±4 : APPROX. 5.3

2±5 : APPROX. 3.7

3±GROUND : APPROX. 13.2

6±GROUND : APPROX. 13.2

E 2 EFI WATER TEMP. SENSOR
1±2 : APPROX. 16.2K
( ±20 °C ±4 °F)
APPROX. 2.5K
( 20 °C 68 °F)
APPROX. 0.32K
( 80 °C 176 °F)
E 8 ECT PATTERN SELECT SW
4±3 : CLOSED WITH ECT PATTERN SELECT SW AT POWER POSITION
E 9(A), E10(B) ENGINE AND ECT ECU
BATT ± E1: ALWAYS APPROX. 12 VOLTS
IGSW ± E1: APPROX. 12 VOLTS WITH IGNITION SW ON
BK ± E1: APPROX. 12 VOLTS WITH BRAKE PEDAL DEPRESSED
P ± E1: APPROX. 12 VOLTS WITH IGNITION SW ON POSITION AND ECT PATTERN SELECT SW AT POWER POSITION
KD±GROUND :CONTINUITY WITH KICK DOWN SW ON
OD2 ± E1: APPROX. 12 VOLTS WITH O/D MAIN SW ON
0 VOLTS WITH O/D MAIN SW ON
+B±GROUND : APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION
+B1±GROUND : APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION
MREL±GROUND:APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION
E01±GROUND : ALWAYS CONTINUITY
E02±GROUND : ALWAYS CONTINUITY
L±GROUND : APPROX. 12 VOLTS WITH SHIFT LEVER AT ªLº RANGE
2±GROUND : APPROX. 12 VOLTS WITH SHIFT LEVER AT ª2º RANGE
R±GROUND : APPROX. 12 VOLTS WITH SHIFT LEVER AT ªRº RANGE
E1±GROUND : ALWAYS CONTINUITY
VC±VTA1 : LESS THAN 1 VOLTS WITH THROTTLE VALVE FULLY CLOSED
MORE THAN 3 VOLTS WITH THROTTLE VALVE OPEN
VTA1 ± E2: CONTINUITY WITH THROTTLE VALVE FULLY CLOSED APPROX. 4K
WITH THROTTLE VALVE FULLY OPEN
VC ± E2: APPROX. 5 VOLTS
O 1 O/D DIRECT CLUTCH SPEED SENSOR
1±2 : APPROX. 620

S 4 SPEED SENSOR NO.2 (FOR ECT)
1±2 : APPROX. 620

S12 STOP LIGHT SW
2±1 : CLOSED WITH BRAKE PEDAL DEPRESSED
SERVICE HINTS
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132
ECT AND A/T INDICATOR
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
A2128E 226S 927
C 326E 828S22B29
C12C28E 9A28S23A29
C13B28E10B28T 227
C14A28N 127T 629
D1326O 529S 327
E 126S 427
: 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)
1E20INSTRUMENT PANEL WIRE
1H
1I20COWL WIRE1J20COWL WIRE
1K
3A
3B22INSTRUMENT PANEL WIRE3D22INSTRUMENT 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)EB234ENGINE WIRE AND ENGINE ROOM MAIN WIRE (FRONT SIDE OF R/B NO. 2)
IG236INSTRUMENT PANEL WIRE AND COWL WIRE (R/B NO. 5)
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)
: GROUND POINTS
CODESEE PAGEGROUND POINTS LOCATION
EB34FRONT SIDE OF LEFT FENDER
ED34REAR SIDE OF CYLINDER HEAD RH
IF36LEFT KICK PANEL
IH36UNDER THE ASHTRAY LH
: SPLICE POINTS
CODESEE PAGEWIRE HARNESS WITH SPLICE POINTSCODESEE PAGEWIRE HARNESS WITH SPLICE POINTS
E1834ENGINE WIREI2238INSTRUMENT PANEL WIRE
E2034ENGINE WIREI3238ENGINE WIREI1938INSTRUMENT PANEL WIREI3338ENGINE WIRE
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