1991 LEXUS SC400 heater

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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Position of Parts in Instrument Panel
H 7 Hazard SW S 10 Shift Lock ECUS 11 Step Light
I 14 Ignition Key Cylinder Light S 12 Stop Light SW
I 15 Ignition SW, Unlock Warning SW and Key Inter Lock Solenoid S 22 Short Connector
I 16 Integration Relay S 23 Short Connector S 24 Seat Heater SW (for M/T)
K 3 Kick Down SW T 6 TDCL (Total Diagnostic Communication Link)
L 1 Luggage Compartment Door Open SW T 7 Telescopic Position Sensor T 8 Theft Deterrent and Door Lock Control ECU
N 4 Noise Filter (for A/C System) T 9 Theft Deterrent and Door Lock Control ECU T 10 Tilt and Power Telescopic ECU
O 5 O/D Main SW T 11 Tilt and Power Telescopic ECU T 12 Traction Cut SW and Seat Heater SW (for A/T)
P 2 PPS ECU T 13 Traction ECU (for A/T)
P 3 Parking Brake SW T 14 Traction ECU (for A/T) T 15 Trip SW and Theft Deterrent Indicator Light
R 2 Radio and Player
R 3 Radio and Player W 6 Water Temp. Sensor (for A/C System)
R 4 Radio and Player (w/ CD Player) W 7 Wireless Door Lock Main SW
R 5 Radio and Player (w/o CD Player)
R 6 Radio and Player (w/o CD Player)
R 7 Remote Control Mirror ECU
R 8 Remote Control Mirror ECU
R 9 Rheostat
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ELECTRICAL WIRING ROUTING
Position of Parts in Seat
B 4 Buckle SW LH P 15 Power Seat Motor (for Driver's Seat Rear Vertical Control)
B 5 Buckle SW RH P 16 Power Seat Motor (for Driver's Seat Reclining Motor Control)P 17 Power Seat Motor (for Driver's Seat Slide Control)
F 19 Front Vertical Position Sensor P 18 Power Seat Motor (for Passenger's Seat Reclining Control) P 19 Power Seat Motor (for Passenger's Seat Slide Control)
P 8 Power Seat Control SW (for Driver's Seat)
P 9 Power Seat Control SW (for Passenger's Seat) R 19 Rear Vertical Position Sensor
P 10 Power Seat ECU (for Driver's Seat) R 20 Reclining Limit SW
P 11 Power Seat ECU (for Driver's Seat)
P 12 Power Seat ECU (for Passenger's Seat) S 15 Seat Heater (for Driver's Seat Back)
P 13 Power Seat Motor (for Driver's Seat Front Vertical Control) S 16 Seat Heater (for Driver's Seat Cushion)
P 14 Power Seat Motor (for Driver's Seat Lumbar S 17 Seat Heater (for Passenger's Seat Back) Support Control) S 18 Seat Heater (for Passenger's Seat Cushion) S 19 Slide Limit SW
S 20 Slide Position Sensor (for Driver's Seat)
S 21 Slide Position Sensor (for Passenger's Seat)
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66
.
ENGINE CONTROL
THIS SYSTEM UTILIZES AN ECU AND MAINTAINS OVERALL CONTROL OF THE ENGINE, TRANSMISSION AND SO ON. AN OUTLINE O\
F
THE ENGINE CONTROL IS EXPLAINED HERE.
1. INPUT SIGNALS
(1) WATER TEMP. SIGNAL CIRCUITTHE WATER TEMP. SENSOR DETECTS THE ENGINE COOLANT TEMP. AND HAS A BUILT±IN THERMISTOR WITH A RESISTANCE
WHICH VARIES ACCORDING TO THE WATER TEMP. THE WATER TEMP. IS INPUT INTO TERMINAL THW OF ENGINE CONTROL
ECU AS A CONTROL SIGNAL.
(2) INTAKE AIR TEMP. SIGNAL CIRCUIT THE INTAKE AIR TEMP. SENSOR IS INSTALLED IN THE AIR FLOW METER AND DETECTS THE INTAKE AIR TEMP., WHICH IS INPUT
AS A CONTROL SIGNAL TO TERMINAL THA OF ENGINE CONTROL ECU.
(3) OXYGEN SENSOR SIGNAL CIRCUIT THE OXYGEN DENSITY IN THE EXHAUST EMISSION IS DETECTED AND INPUT AS A CONTR\
OL SIGNAL FROM THE OXYGEN
SENSOR NO. 1 AND NO. 2 TO TERMINALS OX1, OX2 OF THE ECU AND FROM THE OXYGEN SENSOR SUB (FOR CALIFORNIA) TO
TERMINAL OX3 OF THE ECU.
TO STABILIZE DETECTION PERFORMANCE BY THE OXYGEN SENSOR SUB (FOR CALIFORNIA)\
IS WARMED. THIS HEATER IS
ALSO CONTROLLED BY THE ECU (HT).
(4) RPM SIGNAL CIRCUIT CRANKSHAFT POSITION IS DETECTED BY THE PICK±UP COIL INSTALLED INSIDE THE DISTRIBUTOR. CRANKSHAFT POSITION
IS INPUT AS A CONTROL SIGNAL TO TERMINALS G1 AND G2 OF THE ECU, AND RPM IS INPUT TO TERMINAL NE.
(5) THROTTLE SIGNAL CIRCUIT THE THROTTLE POSITION SENSOR DETECTS THE THROTTLE VALVE OPENING ANGLE AS A CONTROL SIGNAL, WHICH IS
INPUT INTO TERMINAL VTA1 OF THE ECU. WHEN THE VALVE IS COMPLETELY CLOSED, THE CONTROL SIGNAL IS INPUT INTO
TERMINAL IDL1 .
(6) VEHICLE SPEED CIRCUIT THE VEHICLE SPEED IS DETECTED BY SPEED SENSOR NO. 1 INSTALLED IN THE TRANSMISSION AND THE SIGNAL IS INPUT TO
TERMINAL SPD OF THE ECU VIA THE COMB. METER.
(7) NEUTRAL START SIGNAL CIRCUIT THE NEUTRAL START SW DETECTS WHETHER THE SHIFT POSITION IS IN NEUTRAL OR NOT, AND THE SIGNAL IS INPUT INTO
TERMINAL NSW OF THE ECU.
(8) AIRCONDITIONING SW SIGNAL CIRCUIT THE OPERATING VOLTAGE OF THE A/C MAGNETIC CLUTCH IS DETECTED AND THE SIGNAL IS INPUT INTO TERMINAL ACMG OF
ECU AS A CONTROL SIGNAL.
(9) BATTERY SIGNAL CIRCUIT VOLTAGE IS CONSTANTLY APPLIED TO TERMINAL BATT OF THE ECU. WITH THE IGNITION SW TURNED ON, THE VOLTAGE FOR
ECU START±UP POWER SUPPLY IS APPLIED TO TERMINALS +B AND +B1 OF ECU VIA EFI MAIN RELAY.
THE CURRENT FLOWING THROUGH THE IGN FUSE FLOWS TO TERMINAL IGSW OF THE ECU.
(10) INTAKE AIR VOLUME SIGNAL CIRCUIT INTAKE AIR VOLUME IS DETECTED BY THE AIR FLOW METER AND THE SIGNAL IS INPUT TO TERMINAL KS OF THE ECU AS A
CONTROL SIGNAL.
(11) STOP LIGHT SW SIGNAL CIRCUIT THE STOP LIGHT SW IS USED TO DETECT WHETHER OR NOT THE VEHICLE IS BRAKING AND THE SIGNAL IS INPUT INTO
TERMINAL STP OF THE ECU AS A CONTROL SIGNAL.
(12) STA SIGNAL CIRCUIT TO CONFIRM WHETHER THE ENGINE IS CRANKING, THE VOLTAGE APPLIED TO THE STARTER MOTOR DURING CRANKING IS
DETECTED AND THE SIGNAL IS INPUT INTO TERMINAL STA OF THE ECU AS A CONTROL SIGNAL.
(13) ENGINE KNOCK SIGNAL CIRCUIT ENGINE KNOCKING IS DETECTED BY KNOCK SENSOR NO. 1 AND NO. 2 AND THE SIGN\
AL IS INPUT INTO TERMINALS KNK1 AND
KNK2 AS A CONTROL SIGNAL.
SYSTEM OUTLINE
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2. CONTROL SYSTEM
*EFI (ELECTRONIC FUEL INJECTION) SYSTEM
THE EFI SYSTEM MONITORS THE ENGINE CONDITION THROUGH THE SIGNALS INPUT FROM EACH SENSOR (IN\
PUT SIGNALS
FROM (1) TO (13) ETC.) TO THE ECU. THE BEST FUEL INJECTION TIMING IS DECIDED BASED ON THIS DATA AND THE PROGRAM
MEMORIZED BY THE ECU, AND THE CONTROL SIGNAL IS OUTPUT TO TERMINALS #10, #20, #30, #40, #50 AND #60 OF THE ECU TO
OPERATE THE INJECTOR. (INJECT THE FUEL). THE EFI SYSTEM PRODUCES CONTROL OF FUEL INJECTION OPERATION BY THE
ECU IN RESPONSE TO THE DRIVING CONDITIONS.
* ESA (ELECTRONIC SPARK ADVANCE) SYSTEM
THE ESA SYSTEM MONITORS THE ENGINE CONDITION THROUGH THE SIGNALS INPUT TO THE ECU FROM EACH SENSOR (INPUT
SIGNALS FROM (1), (2), (4) TO (13) ETC.). THE BEST IGNITION TIMING IS DECIDED ACCORDING TO THIS DATA AND THE
MEMORIZED DATA IN THE ECU AND THE CONTROL SIGNAL IS OUTPUT TO TERMINAL IGT THIS SIGNAL CONTROLS THE IGNITER
TO PROVIDE THE BEST IGNITION TIMING FOR THE DRIVING CONDITIONS.
* OXYGEN SENSOR HEATER CONTROL SYSTEM (USA SPEC.)
THE OXYGEN SENSOR HEATER CONTROL SYSTEM TURNS THE HEATER ON WHEN THE INTAKE AIR VOLUME IS LOW (TEMP. OF
EXHAUST EMISSIONS IS LOW), AND WARMS UP THE OXYGEN SENSOR TO IMPROVE DETECTION PERFORMANCE OF THE
SENSOR.
THE ECU EVALUATES THE SIGNALS FROM EACH SENSOR (INPUT SIGNALS FROM (1), (2), (4)\
, (9) TO (11) ETC.,) AND OUTPUTS
CURRENT TO TERMINAL HT TO CONTROL THE HEATER.
* ISC (IDLE SPEED CONTROL) SYSTEM
THE ISC SYSTEM (STEP MOTOR TYPE) INCREASES THE RPM AND PROVIDES IDLING STABILITY FOR FAST IDLE±UP WHEN THE
ENGINE IS COLD, AND WHEN THE IDLE SPEED HAS DROPPED DUE TO ELECTRICAL LOAD AND SO ON. THE ECU EVALUATES
THE SIGNALS FROM EACH SENSOR (INPUT SIGNALS FROM (1), (4), (5), (8)\
, (9), (11) ETC.), OUTPUTS CURRENT TO TERMINAL ISC1,
ISC2, ISC3 AND ISC4 TO CONTROL ISC VALVE.
* EGR CONTROL SYSTEM
THE EGR CONTROL SYSTEM DETECTS THE SIGNAL FROM EACH SENSOR (INPUT SIGNALS \
FROM (1), (4), (9), (10) ETC.), AND
OUTPUTS CURRENT TO TERMINAL EGR TO CONTROL THE EGR VALVE.
* FUEL PUMP CONTROL SYSTEM
THE COMPUTER OUTPUTS CURRENT TO TERMINAL FPC AND CONTROLS THE FUEL PUMP ECU AND FUEL PUMP DRIVE SPEED
IN RESPONSE TO CONDITIONS.
* ACIS (ACOUSTIC CONTROL INDUCTION SYSTEM)
ACIS INCLUDES A VALVE IN THE BULKHEAD SEPARATING THE SURGE TANK INTO TWO PARTS. THIS VALE IS OPENED AND
CLOSED IN ACCORDANCE WITH THE DRIVING CONDITIONS TO CONTROL THE INTAKE MANIFOLD LENGTH IN TWO STAGES FOR
INCREASED ENGINE OUTPUT IN ALL RANGES FROM LOW TO HIGH SPEEDS.
THE ECU JUDGES THE VEHICLE SPEED BY THE SIGNALS ((4), (5)) FROM EACH \
SENSOR AND OUTPUTS SIGNALS TO THE
TERMINAL ACIS TO CONTROL THE VSV (FOR OPENING AND CLOSING THE INTAKE CONTROL VALVE).
3. DIAGNOSIS SYSTEM
WITH THE DIAGNOSIS SYSTEM, WHEN THERE IS A MALFUNCTION IN THE ECU SIGNAL\
SYSTEM, THE MALFUNCTIONING SYSTEM IS
RECORDED IN THE MEMORY. THE MALFUNCTIONING SYSTEM CAN BE FOUND BY READING THE CODE DISPLAYED BY THE
CHECKING ENGINE WARNING LIGHT.
4. FAIL±SAFE SYSTEM
WHEN A MALFUNCTION HAS OCCURRED IN ANY SYSTEM, IF THERE IS A POSSIBILITY OF \
ENGINE TROUBLE BEING CAUSED BY
CONTINUED CONTROL BASED ON THE SIGNALS FROM THAT SYSTEM, THE FAIL±SAFE SYSTEM EITHER CONTROLS THE SYSTEM
BY USING DATA (STANDARD VALUES) RECORDED IN THE ECU MEMORY OR ELSE STOPS THE ENGINE.
NOTE: THE SPECIFICATION DESCRIPTIONS ªUSA SPEC.º AND ªEXC. USA SPEC.º USED IN THIS SECTION INDICATE THE
FOLLOWING SPECIFICATIONS.
USA SPEC. : USA (50 STATES) SPECIFICATIONS
EXC. USA SPEC. : USA (EXCEPT CALIFORNIA) AND CANADIAN SPECIFICATIONS.
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236
GROUND POINT
FRONT TURN SIGNAL
LIGHT LH
ENGINE HOOD
COURTESY SW
TRACTION PUMP AND
MOTOR
HEATER RELAY
ABS ACTUATOR RELAY
TELEPHONE
TRANSCEIVER
AND SPEAKER RELAY
ENGINE OIL LEVEL
WARNING SW
COMBINATION METER
(E1 )
EFI ECU
TRACTION ECU
CHECK CONNECTOR
(
E1 ) CORNERING LIGHT LH
FRONT SIDE MAKER
LIGHT LH
BRAKE FLUID LEVEL
SW
FRONT CLEARANCE
LIGHT LH
FRONT SIDE MAKER
LIGHT RH
FRONT CLEARANCE
LIGHT RH
ABS ACTUATOR
FRONT TURN SIGNAL
LIGHT RH
CRUISE CONTROL
ACTUATOR
OXYGEN SENSOR SUB
(
FOR USA SPEC. )
TDCL (
E1 )
WASHER LEVEL SW EFI MAIN RELAY
CORNERING LIGHT RH
A/C PRESSURE SW
(HI GH PRESSURE )
AIR FLOW METER POWER STERRI NG
PRESSURE SW
NOISE FI LTER
(
FOR IGNI TION SYSTEM ) E4
E10
E12 2
2
BS1 4 E4
E7
E1 E5
EB EA I23
I33
E1 6
I32
E20
E20
E20
IK2 24
ED EC IK1
1 BY1
5
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W± B W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B BR
BR
W±B BR
BR
BR
W±B BR
BR±B BR BR
BR
BR
W± B
W± B
W± B
W± B
W± B
W± B
W± B
W±B
W±B
BR
BR
BR
BR BR
BR
BR
W±B
BR BR
BR
( EO1 )
( E11 )
( E1 )
( EO2 )
I27BR
(
S1 )
( E1 )
NOISE FILTER (
FOR
IGNITION SYSTEM )W±B
W/ TRACTION SYSTEM
NOI SE FILTER
(
FOR DEFOGGER SYSTEM )
W±B
W±B
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237
GLOVE BOX LIGHT SW
CIGARETTE LIGHTER
LUGGAGE COMPARTMENT
DOOR OPENER SW
COMBINATION METER
(EP )
O/D MAIN SW
RHEOSTAT
DO OR LOCK MOTOR,
DOOR UNLOCK
DETECTION SW AND
DOOR OPEN DETECTION
SW LH
MIRROR HEATER LH DOOR KEY LOCK AND
UNLOCK SW LH
POWER WINDOW
MASTER SW
RE MOTE CO NTROL
MIRROR SW
KEY INTER LOCK
SOLENOID
[IGNITION SW]
UNLOCK WA RNING SW
[IGNITION SW]
TURN SIGNAL SW
[COMB. SW]
WIPER AND WASHER SW
[COMB. SW]
LIGHT CONTROL SW
[COMB. SW]
DIMMER SW
[COMB. SW] INTEGRATION RELAY POWER MAIN RELAY HA ZARD S W A/C CONTROL
ASSEMBLY A/T INDICATOR LIGHT
(
FOR SHIFT LEVER )
SEAT HEATER SW TRACTION CUT SW AND
SEAT HEATER SW SHIFT LOCK ECU
3G 8
3F 8
3F 7
3D 10
3D 9
3A 2
1F 6
1K 6 3H
15
3H 14
3H 3
1D 10
1G 3
1G 4
IF
IG 1E
18 3A
1
W±B W±B W±B
W±B
W±B
W±B W±B W±B
W±B W±B
W±B W±B W±B W±B
W±B W±B
W±B W±B
W±B
W±B
W±B
CE NTER AI RB AG
SENSOR ASSEMBLY
I29
W±B
W±B
3G
3
I38 I8 1K 5
WIPER MOTOR
SEAT HEATER RELAY
KICK DOWN SW
THEFT DETERRENT
AND DOOR LOCK ECU
HE ADLIGHT HI RH
HE ADLIGHT HI LH
COMBINATION METER
(
HIGH BEAM )
CRUISE CONTROL SW
[COMB. SW] E3
I1
4
4
1K
12
IE1
11
IH11
CRUISE CONTROL ECU
( GND ) 1J
1
I7
1G1
8
I5 W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B R
W±B
W±B W±B W±B W±B W±BW±BW±B
W±B W±B W±B
W±B W±B
W±B
W±B
W±B
W±B
W±B W±B
W±B
W±B
IQ1 10
W±B
(E1 )
( E2 )
TILT AND POWER
TELESCOPIC ECU
( GND2 )
W±B ( A/T )
( M/T )
W±B
1H 13
I38
B4
B31
MOO N ROOF CO NTROL
RE LAY
MOON ROOF LIMIT SW
MOO N ROOF MOTOR
MOO N ROOF CO NTROL
SW
PERSONAL LIGHT
VANITY LIGHT LH
VANITY LIGHT RH
PERSONAL LIGHT
VANITY LIGHT RH
VANITY LIGHT LH B3
B1
B1
B2
B
W±B B
W±B
W±B
W±B
W±B
W±B
W±B
W±B W±BW±B
BZ1
4 BZ1
5
B
W±B
W±B
( CANADA )
W±B
( W/O MOON ROOF )(
W/ MOON ROOF )
(
W/O MEMORY MIRROR )
W±B
(
CANADA )
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238
GROUND POINT
RADIO AND PLAYER
WOOFER SPEAKER
AMP LIFIER
STEREO POWER
AMP LIFIER
CHOKE COIL
HIGH MOUNT STOP
LIGHT
HIGH MOUNT STOP
LIGHT
FUEL LID OPENER
SOLENOID
WIRELESS DOOR LOCK
ECU
POWER SEAT CONTROL
SW(
FOR PASSENGER' S
SEAT )
POWER SEAT ECU
( FOR PASSENGER' S
SEAT )
SEAT HEATER RH
( FOR PASSENGER' S
SEAT BACK )
PPS ECU
REMOTE CONTROL
MIRROR ECU I31
II
BV2
8
IQ2
12
B23 : PIONEER
B24 : NAKAMICHI
BR
BR
BR BR
(
W/O CD PLAYER )
( W/ CD PLAYER ) BR
BR
A/C POWER
TRANSISTOR
BLOWER RESISTOR
(
FOR LOW SPEED )
ABS ECU
ABS AND
TRACTION
ECU
TRACTION ECU (
GND )
DOOR LOCK CONTROL
SW
MIRROR HEATER RH DOOR LOCK MOTOR,
D OOR UNL OC K
DETECTION SW AND
DOOR OPEN DETECTION
SW RH DOOR KEY LOCK AND
UNLOCK SW RH
HEADLIGHT LO LH
I25
I14 B33
B6
B7
HEADLIGHT LO RH
B20
B21
B29
E1
I11 I12 I13
IJ
BL
Bd1
2
Bb14
IJ113
IP1 20
IN1
1
IE2
12
IE1
19
BX1
10
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B W±B W±B W±B W±B W±B
W±B
W±B W±B W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B W±B
W±B
W±B
W±B W±B
W±B
(
W/ REAR SPOILER )
( W/O REAR SPOILER )
W±BW±B
W±B W±B
(
GN D2 )
( GN D3 )
( GN D2 )
( GN D3 )
(
GN D1 )
W±B
W±B
BR
I27
W±B
W±B
WOOFER SPEAKER
AMP LIFIER
BU28
(W/O CD PLAYER )
P±L BR
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