1991 LEXUS SC400 clutch

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.
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228
AUTOMATIC AIR CONDITIONER
222 22 22
2
1A
5
222 22 22
I32
E11
I27 I27
EB IJ
1K
2
IN16
II1
5
II1
2
IR24
IJ2
2
EB1 2
IR22
IR2
1
IR2
6
IN1
1
IN1
3
IE 2
12
EB1
1
M
1 2
4
2 1
A
B
BB
1212 IR2
10
IR2 9
23 34
R±L R±L
R±LR±L
R±L
R±Y L±RL±Y
L±W
Y
B±R
R
L±W R±L
B
R±L
R±L
R±L
R±L
B
L±R
W
W
L±W
L±W L±R
W±B
L±R
L
L±R
W±B
W±B W±B W±B W±BRY
B±R
W±B
R L L
R±L
R±L
FROM POWER SOURCE SYSTEM
(
SEE PAGE 56 )
10A
HEATER
60A
HEATER
HEA TER
RELAY A/C MAGNETIC
CLUTCH RELAYENGINE AND ECT ECU
DEFOGGER
RELAY
BLOWER
MOTOR
A/C MAGNETIC CLUTCH BLOWER RESISTOR
(FOR LOW SPEED )
A/C POWER
TRANSISTOR A1 7
,A1 8
B3
A2
E9
B2 ACMG A/C
B
R±Y43 13 51 42
2 12
34
R±LB
L±O
W±G
IN1
2
AA
1
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233
A 2 A/C MAGNETIC CLUTCH
4±GROUND : APPROX. 3.7

A 3 A/C PRESSURE SW
4±1 : OPEN ABOVE APPROX. 15.5KG/CM2 ( 30 PSI, 206 KPA) OR 27 KG/CM2
(384 PSI, 2648 KPA)
A17, A18 POWER TRANSISTOR
(B) 1± (A) 2 : APPROX. 2.0±2.4K

A12, A13, A14 A/C CONTROL ASSEMBLY
+B ± GROUND: ALWAYS APPROX. 10±14 VOLTS
IG + ± GROUND: APPROX. 10±14 VOLTS WITH IGNITION SW AT ON POSITION
HR ± GROUND: APPROX. 10±14 VOLTS WITH IGNITION SW AT ON POSITION AND DO NOT TURN THE BLOWER MOTOR
BELOW 1 VOLTS WITH IGNITION SW AT ON POSITION AND TURN THE BLOWER MOTOR
LP ± GROUND: NO CONTINUITY WITH PRESSURE LESS THAN 2.1 KG/CM
2 (30 PSI, 206 KPA) OR ABOVE 27 KG/CM2
(384 PSI, 2648 KPA)
ACC ± GROUND: APPROX. 10±14 VOLTS WITH IGNITION SW AT ACC OR ON POSITION
WV ± GROUND: 10±14 VOLTS AT START THE ENGINE AND MAX. COLD POSITION OF A/C TEMP. CONTROL SW
BELOW 1 VOLTS AT START THE ENGINE AND MAX. WARM POSITION OF A/C TEMP. CONTROL SW
MGC ± GROUND: BELOW 1 VOLTS AT START THE ENGINE, PUSH THE A/C AUTO SW AND A/C SW ON POSITION
10±14 VOLTS AT START THE ENGINE, PUSH THE A/C AUTO SW AND A/C SW OFF POSITION
BLR ± GROUND: BELOW 1.5 VOLTS WITH THE IGNITION SW ON AND TURN THE BLOWER MOTOR
S5 ± GROUND: 4±6 VOLTS WITH THE IGNITION SW ON
SG ± GROUND: ALWAYS CONTINUITY
MH ± MC : 13±19 VOLTS WITH IGNITION SW OFF
MFRS ± GROUND: APPROX. 12 VOLTS WITH FRESH SW ON
MREC ± GROUND: APPROX. 12 VOLTS WITH RECIRC SW ON
MFACE ± GROUND: APPROX. 12 VOLTS WITH FACE SW ON
MDEF ± GROUND: APPROX. 12 VOLTS WITH DEF SW ON
E ± GROUND: ALWAYS CONTINUITY
B 3 BLOWER RESISTOR (FOR LOW SPEED)
1±2 : APPROX. 2.6±3.0

: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
A 126A18B28E 9A28
A 226A1928I 227
A 326A2028I1629
A12C28A2728N 429
A13A28A2828R 929
A14B28A3328T 629
A1528B 228V 427
A1628B 328W 429
A17A28C 326
: 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
1E20INSTRUMENT PANEL WIRE
1I
1J20COWL WIRE
1K
20COWL WIRE
3A
3B
3E23INSTRUMENT PANEL WIRE
3G
3H
SERVICE HINTS
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220
COMBINATION METER*1 : W/ TRACTION CONTROL
* 2 : W/O TRACTION CONTROL
2
1
3D
4 3A
6 1E
11
1B5
IK1
12 IK1 11 IK1 13 IK114
IK2
10
OPEN DOOR
RE AR LIGHT
BRAKE
ECT POWER P
R
N
D
C
11 A
17
C
12 A 1A2A 3A4
A
12 B 8
1 2
2 1
EA
10A
DOME
G±O
W±B
W±B
RR
R
G±O
B
GR
R±B
L
G±W
G±W L
R±B
GR
V±R
R±W
V±R
R±W
B
W±B R±W FROM
NEUTRAL START SW
(
A/T )
CLUTCH S TART SW (
M/T )
FROM A/T INDICATOR SW
FROM POWER SOURCE SYSTEM
(
SEE PAGE 56 )
DIODE
(
FOR PARKING
BRAKE )
PARKING
BRAKE SW
COMBINATION METER
P3 D2
C12
,C13 , C1 4
ABC
2
B
4
G±O
FROM ECT PATTERN
SELECT SW
COOLANT LEVEL
TO INTEGRATION
RELAY
BU1
9 B
11
TO LIGHT FAILURE
SENSOR V±G V±G
V±R IE1
1
IG1 20
A
13
R±WI7
I4
2 1
B
DIODE
(
FOR B RAK E
FLUID LEVEL SW )
D1
IG1
19
3E
2
3C
2
R±W
1BRAKE FLUID
LEVEL SW B1 (*2 ) B
IK2
23
R±W R±W
R±W R±W
( CANADA )
(
USA )
R±W
R±W
( USA )
B
(CA NADA )
( *1 )
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26
ELECTRICAL WIRING ROUTING
Position of Parts in Engine Compartment
A 1 A/C Ambient Temp. Sensor E 1 ECT Solenoid
A 2 A/C Lock Sensor and A/C Magnetic Clutch E 2 EFI Water Temp. Sensor
A 3 A/C High Pressure SW E 3 EGR Gas Temp. Sensor (for USA Spec.)
A 4 ABS Actuator E 5 Engine Hood Courtesy SW
A 5 ABS Actuator (w/ Traction Control) E 6 Engine Oil Level Warning SW
A 6 ABS Actuator (w/ Traction Control)
A 7 ABS Speed Sensor Front LH F 1 Front Airbag Sensor LH
A 8 ABS Speed Sensor Front RH F 2 Front Airbag Sensor RH
A 9 Air Flow Meter F 3 Front Clearance Light LH
A 10 Alternator F 4 Front Clearance Light RH
A 11 Alternator F 5Front Side Marker Light LH
A 33 ABS Actuator (w/o Traction Control) F 6 Front Side Marker Light RH F 7 Front Turn Signal Light LH
B 1 Brake Fluid Level SW F 8 Front Turn Signal Light RH
B 6 Back±Up Light SW (for M/T) F 9 Fuse Block
C 3 Check Connector H 1 Headlight Hi LH
C 6 Cornering Light LH H 2 Headlight Hi RH
C 7 Cornering Light RH H 3 Headlight Lo LH
C 8 Cruise Control Actuator H 4 Headlight Lo RH H 5 Horn LH
D 13 Distributor H 6 Horn RH
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28
ELECTRICAL WIRING ROUTING
Position of Parts in Instrument Panel
A 12 A/C Control Assembly C 9 CD Player
A 13 A/C Control Assembly C 10 Center Airbag Sensor Assembly
A 14 A/C Control Assembly C 11 Cigarette Lighter
A 15 A/C Control SW and Radio SW C 12 Combination Meter
A 16 A/C Evaporator Temp. Sensor C 13 Combination Meter
A 17 A/C Power Transistor C 14Combination Meter
A 18 A/C Power Transistor C 15 Combination SW
A 19 A/C Room Temp. Sensor C 16 Combination SW
A 20 A/C Solar Sensor C 17 Combination SW
A 21 A/T Indicator Light (for Shift Lever) C 19 Cruise Control ECU
A 22 ABS ECU (for M/T, w/o Traction Control) C 23 Clutch Start SW
A 23 ABS ECU (for M/T, w/o Traction Control) C 24 Cruise Control Clutch SW
A 24 ABS and Traction ECU
A 25 ABS and Traction ECU D 1 Diode (for Brake Fluid Level)
A 26 ABS and Traction ECU D 2 Diode (for Parking Brake)
A 27 Air Mix Control Servo Motor D 3 Diode (for Tension Reduser)
A 28 Air Vent Mode Control Servo Motor
A 29 Airbag Squib E 8 ECT Pattern Select SW
A 33 Air Inlet Control Servo Motor E 9 Engine and ECT ECU (for A/T) E 10 Engine and ECT ECU (for A/T)
B 2 Blower Motor E 11 Engine ECU (for M/T)
B 3 Blower Resistor (for Low Speed) E 12 Engine ECU (for M/T)
F 10 Fuel Lid Opener SW
G 1 Glove Box Light
G 2 Glove Box Light SW
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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
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