ect LEXUS SC300 1991 Service Repair Manual

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

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
WhereEverybodyKnowsYourName

232
AUTOMATIC AIR CONDITIONER
IR2
7IQ1 8
IQ1
19
IQ1
10
IQ1
4 1E
18
3H
13
1J
1
3E
33H 12
ED IF EA 4
1
L±B
L±B
W±B
P±L
P±B
W±G
W±B P±L
P±B
W±G
L±B
P±L
P±B
P±B
BR
W±B
W±B W±B W±B
L±G
A
2B 5C7B17 B 6 E1 E1
A/C TC TC OP1
DIN
DOUT
E
PSW
REOST
A/C CONTROL ASSEMBLY TDCL
(
TOTAL DIAGNOSTIC
COMMUNICATION LINK )CHECK
CONNECTOR
A/C PRESSURE SW
A1 2 , A1 3 ,
A14 T6 C3
A3
11 4 11
3
CAB IK1
10
P±B
3A
12
3H
10 3G 33A
1
A
5A 6
IQ1
18 IQ1 23A
9
3G
2 IG1
5 1I
3
W±B
G±O
G±O
G±O
G
G LL
W±G
8
6 FROM POWER SOURCE SYSTEM
(
SEE PAGE 56 )
7. 5A
PANEL
I16
INTEGRATION
RE LAY
(
CA NADA )(
USA )
RHEOSTAT R9
TC TAIL IN1
5
A
5
A
WhereEverybodyKnowsYourName

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
WhereEverybodyKnowsYourName

234
AUTOMATIC AIR CONDITIONER
: 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)
II136ENGINE WIRE AND A/C WIRE (BEHIND GLOVE BOX)
IJ236ENGINE WIRE AND COWL WIRE (RIGHT KICK PANEL)
IK136ENGINE WIRE AND INSTRUMENT PANEL WIRE (RIGHT KICK PANEL)
IN138ENGINE ROOM MAIN WIRE AND A/C WIRE (BEHIND GLOVE BOX)
IQ138INSTRUMENT PANEL WIRE AND CONSOLE BOX WIRE (UNDER THE INSTRUMENT PANEL CENTER)
IR138CONSOLE BOX WIRE AND A/C SUB WIRE (BEHIND GLOVE BOX)IR238CONSOLE BOX WIRE AND A/C SUB WIRE (BEHIND GLOVE BOX)
: GROUND POINTS
CODESEE PAGEGROUND POINTS LOCATION
EA34FRONT SIDE OF RIGHT FENDER
EB34FRONT SIDE OF LEFT FENDER
ED34REAR SIDE OF INTAKE MANIFOLD
IF36LEFT KICK PANEL
IJ36RIGHT KICK PANEL
: SPLICE POINTS
CODESEE PAGEWIRE HARNESS WITH SPLICE POINTSCODESEE PAGEWIRE HARNESS WITH SPLICE POINTS
E1134ENGINE ROOM MAIN WIREI2838CONSOLE BOX WIREE1834ENGINE WIREI2938CONSOLE BOX WIRE
I2738A/C WIREI3238ENGINE WIRE
WhereEverybodyKnowsYourName

4
XXXX10 4
XXXX10
BDB
R2 R2
A32
12 3
45678 A
A32
13
8X A
R4
3
89
C
R5
X23 456
7891011121314
205
A32 AUTO ANTENNA MOTOR AND RELAY
3±GROUND : ALWAYS APPROX. 12 VOLTS
6±GROUND : APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION
8±GROUND : APPROX. 12 VOLTS WITH IGNITION SW AT ACC OR ON POSITION
7±GROUND : ALWAYS CONTINUITY
R 4(A), R 5(C) RADIO AND PLAYER
(A) 3, (C) 3±GROUND : APPROX. 12 VOLTS WITH IGNITION SW AT ACC OR ON POSITION
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
A32A30R2A29 (W/ CD PLAYER)R 4B29 (W/ CD PLAYER)A32B30R 2D29 (W/O CD PLAYER)R 5C29 (W/O CD PLAYER)
: 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)
IG236INSTRUMENT PANEL WIRE AND COWL WIRE (R/B NO. 5)
IQ138INSTRUMENT PANEL WIRE AND CONSOLE BOX WIRE (UNDER THE INSTRUMENT PANEL CENTER)IQ238INSTRUMENT PANEL WIRE AND CONSOLE BOX WIRE (UNDER THE INSTRUMENT PANEL CENTER)
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
BM40BACK PANEL CENTER
: SPLICE POINTS
CODESEE PAGEWIRE HARNESS WITH SPLICE POINTSCODESEE PAGEWIRE HARNESS WITH SPLICE POINTS
I3138CONSOLE BOX WIRE
SERVICE HINTS
WhereEverybodyKnowsYourName

101
BACK±UP LIGHT
1H
12
IJ110
IK111
BU18
B15
B15BM
YY R±B R±B R±B R±B
W±B
R±B
W±B
W±B
44
55
10A
GAUGE
R±B
W±B
BACK±UP
LIGHT SW
BACK±UP LIGHT
[REAR COMB. LIGHT]
LH RH
R10 R11
FROM POWER SOURCE SYSTEM
(
SEE PAGE 56 )
4
9 R10, R11
GRAY B6 , N1
BA
X4
5
A
N1
12 B
B6 GRAY B
AAB 92 41
(A/T )
( M/T )
N 1 BACK±UP LIGHT SW
4±9 : CLOSED WITH SHIFT LEVER IN R POSITION
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
B 6B26R1031
N 1A27R1131
: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR
CODESEE PAGEJUNCTION BLOCK AND WIRE HARNESS (CONNECTOR LOCATION)
1H20COWL WIRE
: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS
CODESEE PAGEJOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)
IJ136ENGINE WIRE AND COWL WIRE (RIGHT KICK PANEL)
IK136ENGINE WIRE AND INSTRUMENT PANEL WIRE (RIGHT KICK PANEL)
BU140FLOOR WIRE AND INSTRUMENT PANEL WIRE (LEFT KICK PANEL)
: GROUND POINTS
CODESEE PAGEGROUND POINTS LOCATION
BM40BACK PANEL CENTER
: SPLICE POINTS
CODESEE PAGEWIRE HARNESS WITH SPLICE POINTSCODESEE PAGEWIRE HARNESS WITH SPLICE POINTS
B1540FLOOR MAIN WIRE
SERVICE HINTS
WhereEverybodyKnowsYourName

208
CELLULAR MOBILE TELEPHONE
T16 (A) TELEPHONE TRANSCEIVER AND SPEAKER RELAY
(A) 9±GROUND : ALWAYS APPROX. 12 VOLTS
(A) 10±GROUND : APPROX. 12 VOLTS WITH IGNITION SW AT ACC OR ON POSITION
(A) 11±GROUND : ALWAYS CONTINUITY
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
C1628R 4A29 (W/ CD PLAYER)S1431
F1230R 5B29 (W/O CD PLAYER)T16A31
M 131R 6C29 (W/O CD PLAYER)T17B31
: 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
: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS
CODESEE PAGEJOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)
IP138FRONT DOOR RH WIRE AND COWL WIRE (RIGHT KICK PANEL)
BS140ENGINE ROOM MAIN WIRE AND FLOOR WIRE (LEFT KICK PANEL)
BT140FLOOR WIRE AND COWL 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 COWL WIRE (UNDER THE LEFT SIDE OF REAR SEAT CUSHIONBc240FLOOR NO. 3 WIRE AND COWL WIRE (UNDER THE LEFT SIDE OF REAR SEAT CUSHION
: GROUND POINTS
CODESEE PAGEGROUND POINTS LOCATION
EB34FRONT SIDE OF LEFT FENDER
: SPLICE POINTS
CODESEE PAGEWIRE HARNESS WITH SPLICE POINTSCODESEE PAGEWIRE HARNESS WITH SPLICE POINTS
I 338COWL WIREB3440FLOOR MAIN WIREI 838COWL WIREB3540FLOOR MAIN WIRE
I 2638ENGINE ROOM MAIN WIREB3640FLOOR NO. 3 WIRE
B 840FLOOR MAIN WIRE
SERVICE HINTS
WhereEverybodyKnowsYourName

61
A10(A) ALTERNATOR
(A) 1±GROUND : 13.9±15.1 VOLTS WITH ENGINE RUNNING AT 2000 RPM AND 25°C ( 77°F)
13.5±14.3 VOLTS WITH ENGINE RUNNING AT 5000 RPM AND 11 5°C ( 239 °F)
(A) 2±GROUND : 0±4 VOLTS WITH IGNITION SW AT ON POSITION AND ENGINE NOT RUNNING
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
A10A26C1228
A11B26F 926
: 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
1H20COWL WIRE
3D22INSTRUMENT PANEL WIRE
: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS
CODESEE PAGEJOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)
EB234ENGINE 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)
IG338INSTRUMENT PANEL WIRE AND COWL WIRE (RIGHT KICK PANEL)
IJ136ENGINE WIRE AND COWL WIRE (RIGHT KICK PANEL)IJ236ENGINE WIRE AND COWL WIRE (RIGHT KICK PANEL)
: SPLICE POINTS
CODESEE PAGEWIRE HARNESS WITH SPLICE POINTSCODESEE PAGEWIRE HARNESS WITH SPLICE POINTS
I1438COWL WIRE
X X
14 15 6 5
7
1
23 1
B
A
A10 A11 C12 F 9 BLACK BLACK
SERVICE HINTS
WhereEverybodyKnowsYourName

169
CIGARETTE LIGHTER
1E
2
3A5
3F5
3F8
1E18
3A 1
1J1
IF
FROM POWER SOUR CE SYSTEM
(
SEE PAGE 56 )
15A
CIG
CIGARETTE
LIGHTER C11
L±R L±R
W±B W±B
W±B
4 2
C11 CIGARETTE LIGHTER
2±GROUND : APPROX. 12 VOLTS WITH IGNITION SW AT ACC OR ON POSITION
4±GROUND : ALWAYS CONTINUITY
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
C1128
: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR
CODESEE PAGEJUNCTION BLOCK AND WIRE HARNESS (CONNECTOR LOCATION)
1E20INSTRUMENT PANEL WIRE
1J20COWL WIRE
3A23INSTRUMENT PANEL WIRE3F23INSTRUMENT PANEL WIRE
: GROUND POINTS
CODESEE PAGEGROUND POINTS LOCATION
IF36LEFT KICK PANEL
2
4
C11
BLUE
SERVICE HINTS
WhereEverybodyKnowsYourName