1991 LEXUS SC300 window

2HEAT METHOD: When the problem seems to occur when the suspect area is heate\
d.
Heat the component that is likely the cause of the mal-
function with a hair dryer or similar object. Check to see
if the malfunction will occur.
Notice:

Do not heat to more than 60 C (140 F) (Tempera-
ture limit that the component can be touched with a
hand.)

Do not apply heat directly to any part in the ECU.
3WATER SPRINKLING METHOD: When the malfunction seems to occur on a rainy day or in
a high±humidity condition.
Sprinkle water onto the vehicle and check to see if the
malfunction will occur.
Notice: Never apply water directly onto the
electronic components.
HINT:

If the vehicle is subject to water leakage, the leaked
water may contaminate the ECU. When testing a ve-
hicle with a water leakage problem, special caution
must be paid.
4OTHER: When a malfunction seems to occur when electrical load is excessive.
Turn on all electrical loads including the heater blower,
headlights, rear window defogger, etc. and check to see
if the malfunction will occur.
RS±66±
SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTING
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AIR CONDITIONING EVAPORATOR ODOR ± AC001±97 September 12, 1997
General1. Preparation of freshener solution:
Procedure (a) Invert freshener container and shake vigorously for 30 seconds.
(b) Mix 3.4 fl. oz. of freshener (1 container) with 30 fl. oz. to make 1 q\
t. of solution.
2. Drying the evaporator: Dry the evaporator for 10 minutes with the following settings:
A/C: Off
. . . . . . . . . . .
Air Outlet: Foot
. . . . . .
Mode: Recirc.
. . . . . . . . . .
Blower: High
. . . . . . . .
Te m p : Max Warm
. . . . . . . . . .
3. Evaporator Treatment Preparation: (a) Ensure availability of 30±45 psi compressed air to be used with spray\
gun for application of freshener.
(b) Place a tray under the evaporator housing drain hose to collect used cle\
aning solution.
(c) Place shop cloth under the evaporator housing in the vehicle to prevent \
cleaning solution from dripping onto the floor mat.
4. Vehicle Preparation: See specific model section.
5. Evaporator treatment: (a) Set HVAC mode as follows: A/C: Off
. . . . . . . . . . .
Air Outlet: Face
. . . . . .
Mode: Fresh
. . . . . . . . . .
Blower: High
. . . . . . . .
Te m p : Max Warm
. . . . . . . . . .
Windows: Open
. . . . . .
(b) Insert spray nozzle into the filter inlet and spray the entire quantity (1 qt.) of
freshener solution into the evaporator
while moving the nozzle around to
cover the complete evaporator surface.
(c) Turn the blower OFF.
6. Reinstallation of Parts.
7. Completion of Treatment. (a) Dry the evaporator for 30 minutes with the following settings:
A/C: Off
. . . . . . . . . . .
Air Outlet: Foot
. . . . . .
Mode: Recirc.
. . . . . . . . . .
Blower: High
. . . . . . . .
Te m p : Max Warm
. . . . . . . . . .
Windows: Closed
. . . . . .
(b) If the vehicle still has alcohol smell, open windows for ventilation. Do not turn on
the AC switch until the evaporator is
completely dry as this can reduce the
effectiveness of the solution.
Page 2 of 11
CAUTION
Do not get into the vehicle during
this drying operation.
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203
WITH THE IGNITION SW TURNED ON, THE CURRENT FLOWS TO TERMINAL (A)14 OF THE WIPER AND WASHER SW, TERMINAL 2 OF
THE WASHER MOTOR AND TERMINAL 6 OF THE WIPER MOTOR THROUGH THE WIPER FUSE.
1. LOW SPEED POSITION
WITH WIPER SW TURNED TO LOW POSITION, THE CURRENT FLOWS FROM TERMINAL (A)14 OF THE WIPER AND WASHER SW "
TERMINAL (B)8 " TERMINAL 3 OF THE WIPER MOTOR " TERMINAL 1 " TO GROUND AND CAUSES TO THE WIPER MOTOR TO RUN
AT LOW SPEED.
2. HIGH SPEED POSITION
WITH WIPER SW TURNED TO HIGH POSITION, THE CURRENT FLOWS FROM TERMINAL (A)14 OF THE WIPER AND WASHER SW "
TERMINAL (A)7 " TERMINAL 2 OF THE WIPER MOTOR " TERMINAL 1 " TO GROUND AND CAUSES TO THE WIPER MOTOR TO RUN
AT HIGH SPEED.
3. INT POSITION
WITH WIPER SW TURNED TO INT POSITION, THE RELAY OPERATES AND THE CURRENT WHICH IS CONNECTED BY RELAY
FUNCTION FLOWS FROM TERMINAL (A)14 OF THE WIPER AND WASHER SW " TERMINAL (A)6 " TO GROUND . THIS FLOW OF
CURRENT OPERATES THE INTERMITTENT CIRCUIT AND THE CURRENT FLOWS FROM TERMINAL (A)14 OF THE WIPER AND
WASHER SW " TERMINAL (B)8 " TERMINAL 3 OF THE WIPER MOTOR " TERMINAL 1 " TO GROUND AND FUNCTIONS.
THE INTERMITTENT OPERATION IS CONTROLLED BY A CONDENSER'S CHARGED AND DISCHARGED FUNCTION INST\
ALLED IN
RELAY AND THE INTERMITTENT TIME IS CONTROLLED BY A TIME CONTROL SW TO CHARGE THE CHARGING TIME OF THE
CONDENSER.
4. MIST POSITION
WITH WIPER SW TURNED TO MIST POSITION, THE CURRENT FLOWS FROM TERMINAL (A)14 OF THE WIPER AND WASHER SW "
TERMINAL (B)8 " TERMINAL 3 OF THE WIPER MOTOR " TERMINAL 1 " TO GROUND AND CAUSES TO THE WIPER MOTOR TO RUN
AT LOW SPEED.
5. WASHER CONTINUOUS OPERATION
WITH WASHER SW TURNED TO ON, THE CURRENT FLOWS FROM TERMINAL 2 OF THE WASHER MOTOR " TERMINAL 1 "
TERMINAL (A)13 OF THE WIPER AND WASHER SW " TERMINAL (A)6 " TO GROUND AND CAUSES TO THE WASHER MOTOR TO
RUN. AND WINDOW WASHER IS JET. THIS CAUSES THE CURRENT TO FLOW WASHER CONTINUOUS OPERATION CIRCUIT IN
TERMINAL (A)14 OF THE WIPER AND WASHER SW " TERMINAL (B)8 " TERMINAL 3 OF THE WIPER MOTOR " TERMINAL 1 TO
GROUND AND FUNCTION.
C15(B), C16(A) WIPER AND WASHER SW [COMB. SW]
(A) 6±GROUND : ALWAYS CONTINUITY
(A) 14±GROUND : APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION
(B) 8±GROUND : APPROX. 12 VOLTS WITH WIPER AND WASHER SW AT LOW OR MIST POSITION
APPROX. 12 VOLTS EVERY APPROX. 1 TO 10 SECONDS INTERMITTENTLY WITH WIPER SW AT INT POSITION
(B) 17±GROUND : APPROX. 12 VOLTS WITH IGNITION SW ON UNLESS WIPER MOTOR AT STOP POSITION
(A) 7±GROUND : APPROX. 12 VOLTS WITH IGNITION SW ON AND AFTER WIPER SW OFF UNTIL WIPER MOTOR STOPS
W 5 WIPER MOTOR
6±5 : CLOSED UNLESS WIPER MOTOR AT STOP POSITION
SYSTEM OUTLINE
SERVICE HINTS
WhereEverybodyKnowsYourName

31
Position of Parts in Body
M 1 Mobilephone R 16 Remote Control Mirror LH
M 2 Moon Roof Control Relay R 17 Remote Control Mirror RH
M 3 Moon Roof Control SW R 18 Remote Control Mirror SW
M 4 Moon Roof Motor and Limit SWS 13 Stereo Power Amplifier
O 8 Oxygen Sensor Sub (for California) S 14 Stereo Power Amplifier
P 4 Power Window Control SW RH T 16 Telephone Transceiver and Speaker Relay
P 5 Power Window Master SW and Door Lock Control SW LH T 17 Telephone Transceiver and Speaker Relay
P 6 Power Window Motor LH T 18 Tension Reducer Solenoid LH
P 7 Power Window Motor RH T 19 Tension Reducer Solenoid RH
P 20 Personal Light V 5 Vanity Light LH
R 10 Rear Combination Light LH V 6 Vanity Light RH
R 11 Rear Combination Light RH
R 12 Rear Speaker LH W 8 Wireless Door Lock ECU
R 13 Rear Speaker RH W 9 Woofer Speaker
R 14 Rear Window Defogger (+) W 10 Woofer Speaker Amplifier
R 15 Rear Window Defogger (±)
WhereEverybodyKnowsYourName

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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Q
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U
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W
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6
HOW TO USE THIS MANUAL
WITH THE IGNITION SW TURNED ON, THE CURRENT FLOWS TO TERMINAL 3 OF THE POWER\
WINDOW MASTER SW, TERMINAL 2 OF THE POWER WINDOW CONTROL RELAY
AND TERMINAL 8 OF THE POWER WINDOW SW THROUGH THE DOOR FUSE.
1.DRIVER'S WINDOW ªMANUAL UPº OPERATION BY MASTER SW
HOLDING MANUAL SW (DRIVER'S) ON ªUPº POSITION LOCATED IN POWER WINDOW MASTER SW, THE CURRENT FLOWS TO TERMINAL 5 OF THE POWER W INDOW
CONTROL RELAY THROUGH TERMINAL 3 OF THE MASTER SW TERMINAL 2 TO OPERATE A POWER WINDOW CONTROL RELAY. THUS THE CURRENT INSIDE THE RELAY
FLOWS FROM TERMINAL 2 OF THE RELAY TERMINAL 1 TERMINAL 2 OF THE POWER WINDOW MOTOR  TERMINAL 1  TERMINAL 4 OF THE RELAY  TERMINAL
3  TO GROUND. THE MOTOR TURNS TO ASCENT THE WINDOW. RELEASING THIS SW, THE ROTATION OF MOTOR IS STOPPED AND THE WINDOWS CAN STOP AT WILL
POINT.
(FOR THE ªMANUAL DOWNº OPERATION, CURRENT FLOWS IN THE REVERSE DIRECTION BECAUSE THE TERMINALS WHERE\
IT FLOWS ARE CHANGED).
2.DRIVER'S WINDOW ªAUTO DOWNº OPERATION BY MASTER SW
ONCE THE ªAUTO DOWNº BUTTON OF THE MASTER SW IS PUSHED, THE CURRENT FLO\
WS TERMINAL 9 OF THE POWER WINDOW CONTROL RELAY THROUGH TERMINAL
3 OF THE MASTER SW TERMINALS 8 AND 9 TO OPERATE THE RELAY. THUS THE CURRENT INSIDE THE POWER WINDOW CONTROL RELAY FLOWS FROM TERMINAL
2 OF THE RELAY TERMINAL 4 TERMINAL 1 OF THE POWER WINDOW MOTOR  TERMINAL 2 TERMINAL 1 OF THE RELAY  TERMINAL 3  TO GROUND.
THE MOTOR CONTINUES THE ROTATION ENABLING TO DESCENT THE WINDOW.
THE WINDOW DESCENDS TO THE END POSITION. THE CURRENT WILL BE CUT OFF TO\
RELEASE THE AUTO DOWN FUNCTION BASED ON THE INCREASING CURRENT
BETWEEN TERMINAL 2 OF THE RELAY AND TERMINAL 1 IN RELAY.
3.DRIVER'S WINDOW AUTO DOWN RELEASE OPERATION BY MASTER SW
HOLDING THE MANUAL SW (DRIVER'S) ON ªUPº POSITION IN OPERATING AUTO DOWN. THE CURRENT FROM TERMINAL 3 OF THE MASTER SW PASSING TERMINAL 2
FLOWS TERMINAL 5 OF THE RELAY AND RELEASES THE AUTO DOWN FUNCTION IN THE POWER WINDOW CONTROL RELAY. RELEASING THE HAND FROM SW, WINDOW
STOPS AND CONTINUING ON TOUCHING SW, THE FUNCTION SWITCHES TO MANUAL UP OPERATION.
4.PASSENGER'S WINDOW UP OPERATION (MASTER SW) AND WINDOW LOCK SW OPERATION
HOLDING PASSENGER'S WINDOW SW (MASTER SW) ON ªUPº, THE CURRENT FLOWS FROM TERMINAL 3 OF THE MASTER SW PASSING TERMINAL 6 TO TERMINAL 3 OF
THE POWER WINDOW SW (PASSENGER'S) TERMINAL 4 TERMINAL 2 OF THE MOTOR TERMINAL 1 TERMINAL 9 OF THE POWER WINDOW SW TERMINAL
7  TERMINAL 1 OF THE MASTER SW TERMINAL 4 TO GROUND. THE MOTOR RUNS TO ASCENT THE WINDOW. RELEASING THIS SW, THE ROTATION OF MOTOR IS
STOPPED AND WINDOW CAN STOP AT WILL PLACE.
SWITCHING THE WINDOW LOCK SW IN ªLOCKº POSITION, THE CIRCUIT IS OP\
ENED AND STOPPED THE MOTOR ROTATION.
(FOR THE DOWN OPERATION, CURRENT FLOWS IN THE REVERSE DIRECTION BECAUSE THE TERMINALS WHERE\
IT FLOWS ARE CHANGED).
P 2 POWER WINDOW CONTROL RELAY
3±GROUND: ALWAYS CONTINUITY
2±GROUND: APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION
5±GROUND: APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION AND MASTER SW AT UP POSITION
8±GROUND: APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION AND MASTER SW AT AUTO DOWN POSITION
9±GROUND: APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION AND MASTER SW AT DOWN OR AUTO DOWN POSITION
P 4 POWER WINDOW MASTER SW
4±GROUND: ALWAYS CONTINUITY
3±GROUND: APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION
WINDOW LOCK SW
OPEN WITH WINDOW LOCK SW AT LOCK POSITION
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
P 221P 421P 621
P 321P 52121
: RELAY BLOCKS
CODESEE PAGERELAY BLOCK (RELAY BLOCK LOCATION)
116R/B NO. 1 (INSTRUMENT PANEL LEFT SIDE)
: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR
CODESEE PAGEJUNCTION BLOCK AND WIRE HARNESS (CONNECTOR LOCATION)
3B14J/B NO. 3 AND COWL WIRE (INSTRUMENT PANEL LEFT SIDE)
: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS
CODESEE PAGEJOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)
ID126FRONT DOOR RH WIRE AND COWL WIRE (RIGHT KICK PANEL)
IH126FRONT DOOR LH WIRE AND COWL WIRE (LEFT KICK PANEL)
: GROUND POINTS
CODESEE PAGEGROUND POINT LOCATION
IC24COWL LEFT
: SPLICE POINTS
CODESEE PAGEWIRE HARNESS WITH SPLICE POINTS
I 524COWL WIRE
SYSTEM OUTLINE
SERVICE HINTS
WhereEverybodyKnowsYourName

Q
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7
:Explains the system outline.
: Indicates values or explains the function for reference during troublesh\
ooting.
: Indicates the reference page showing the position on the vehicle of the \
parts in the system circuit.
Example: Part ªP4º (Power Window Master SW) is on page 21 of the manual.
* The letter in the code is from the first letter of the part, and the number\
indicates its orderin parts starting with that letter.
Part is 4th in order
Power Window Master SW
Example: P
4
:
Indicates the reference page showing the position on the vehicle of Relay Block Connec\
tors in the
system circuit.
Example: Connector ª1º is described on page 16 of this manual and is installed on th\
e left side of the
instrument panel.
: Indicates the reference page showing the position on the vehicle of J/B and Wire H\
arness in the system
circuit.
Example: Connector ª3Bº connects the Cowl Wire and J/B No. 3. It is described on pag\
e 14 of this manual, and is installed on the instrument panel left side.
: Indicates the reference page describing the wiring harness and wiring harness connector (the female
wiring harness is shown first, followed by the male wiring harness).
Example: Connector ªID1ºconnects the front door RH wire (female) and cowl wire (ma\
le). It is described
on page 26 of this manual, and is installed on the right side kick panel.
: Indicates the reference page showing the position of the ground points o\
n the vehicle.
Example: Ground point ªICº is described on page 24 of this manual and is installed\
on the cowl left side.
: Indicates the reference page showing the position of the splice points on the veh\
icle.
Example: Splice point ªI 5º is on the Cowl Wire Harness and is described on\
page 24 of this manual.
WhereEverybodyKnowsYourName

OVERALL ELECTRICAL WIRING DIAGRAM
1234
12 LEXUS SC300
2
1B
5
1F
9 2
1F
8
1I
15
6 237
2 1
4 11 1B
2
1D
91J 21I 7
10 8 9 5 1 4
11 IF2 3 IF2
11 IP1 3 IP1 2 IP1
M
12
M
12
1D
10 1J 1
1F
6
IF
51
42
3
W± B W±B
WW
W± L
Y
Y
5213
4
RR
L±W L±RL±Y
L±B
W±B
R
W±B G± Y
R±L
G±W
L
L
L
Y±R W± L
W
W±B R
G± Y
R
G±Y R± L
G± W
L G±W
R±L
W± B
W± B
10A
DOME
W± L W
1 2
R
60A MAIN
120A ALT
100A AM1
F9
FUSE BLOCK
D4
DAY/NI GHT
SHIFT SW INNER
MIRROR
M2
MOON ROOF CONTROL REL A Y
M3
MOON ROOF
CONTROL S W
POWER WI NDOW
RE LA YP5
POWER WINDOW MASTER SW AND
DOOR LOCK CONTROL SW LH
BATTERY
To Unlock Warning
SW<4±4><5±4>
From Theft Det err ent and
Door Lock ECU< 17±3>
P7
POWER WI NDOW
MOTOR RH
P6
POWER WI NDOW
MOTOR LH P4
POWER WI NDOW
CONTROL S W RHL
L 30A
POWER
POWER
MA I N RE LA Y
W±B
Power
Source Liquid Crystal
Inner Rear
View Mirror
Moon Roof Power Window
OP EN
CL OS E
UP
DOWN1
7 4589
8BZ1 7BZ1 6BZ1 2BZ1V
P
P±L
V± W NO. 2 NO. 1
M
4BZ1 5BZ1
B± Y
W± B
45
1326
B
6
BR
LG W
W± Y
B
W± B W± B
W±B
1BZ1 12
L
M4
MOON ROOF MOTOR
AND LIMIT SW
BZ13
L
R
WINDOW
LOCK 3 2
5 1
B
Left kick panel1
2
5
1F
R
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