ect LEXUS SC300 1991 Service Repair Manual

Q
R
S
T
U
V
W
X
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

* The system shown here is an EXAMPLE ONLY. It is different to the actual circuit shown in the SYSTEM CIRCUITS SECTION.
POWER SOURCE (Current Flow Chart)
The chart below shows the route by which current flows from the battery to \
each electrical source (Fusible Link, Circuit
Breaker, Fuse, etc.) and other parts.
The next page and following pages show the parts to which each electrica\
l source outputs current.
POWER SOURCE
8
HOW TO USE THIS MANUAL
The ªCurrent Flow Chartº section, describes which parts each power so\
urce (fuses, fusible links, and circuit breakers)
transmits current to. In the Power Source circuit diagram, the conditions when ba\
ttery power is supplied to each system are
explained. Since all System Circuit diagrams start from the power source, the power\
source system must be fully understood.
WhereEverybodyKnowsYourName

* The system shown here is an EXAMPLE ONLY. It is different to the actual circuit shown in the SYSTEM CIRCUITS SECTION.
GROUND POINT
9
The ground points circuit diagram shows the connections from all major p\
arts to the respective ground points. When
troubleshooting a faulty ground point, checking the system circuits which use a common ground may help you iden\
tify the
problem ground quickly. The relationship between ground points ( , , and shown below) can also be
checked this way.
WhereEverybodyKnowsYourName

91
IQ1
4 I29 I29
3 2 2 15
11
32
111
10 1
2
3G
2 3H
53F 13H13H 63H2
3H
10 3C
33F 33E63H 93E5
IQ1
2
B
10 A
2
A
9
C
5
G
G
G
G
G
G±O
G±O
G±O
G±O
G±O
W±G
W±G
W±G
W±G
W±G
W±G
W±G
W±G
W±G
W±G G
G
W±G W±G
HA ZARD S W
RADIO AND PLAYER
A/C CONTROL
AND RADIO SW
TRACTION CUT SW
AND SEAT HEATER SW
CIGARETTE LIGHTER
A/T INDICATOR LIGHT
( FOR SHIFT LEVER )
TRI P S W AND THEFT DE TE RRE NT
INDICATOR LIGHT ECT PATTERN
SELECT SW (
W/ CD PLAYER )
( W/O CD PLAYER )
H7
R4 , R5 ,R 6
A1 5
T12
C11
A21
T1 5 E8AB C
REOS TAIL
IQ1
18
L
W±G
W±G
L
L
A1 3
A/C CONTROL
ASSEMBLY25 6
G
WhereEverybodyKnowsYourName

92
ILLUMINATION
TAILLIGHT RELAY5±3 : CLOSED WITH LIGHT CONTROL SW AT TAIL OR HEAD POSITION
C15 LIGHT CONTROL SW [COMB. SW]
3±4 : CLOSED WITH LIGHT CONTROL SW AT TAIL OR HEAD POSITION
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
A1328E 828R 4A29
A1528F 926R 5B29
A2128G 128R 6C29
C1128G 228R 929
C12A28H 729T1229
C14B28I16A29T1529
C1528I16B29
: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR
CODESEE PAGEJUNCTION BLOCK AND WIRE HARNESS (CONNECTOR LOCATION)
1B20ENGINE ROOM MAIN WIRE
1E20INSTRUMENT PANEL WIRE
1I
1J20COWL WIRE
1K
20COWL WIRE
3A
3C
3E22INSTRUMENT PANEL WIRE3F22INSTRUMENT PANEL WIRE
3G
3H
: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS
CODESEE PAGEJOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)
IG136INSTRUMENT PANEL WIRE AND COWL WIRE (R/B NO.5)
IQ138INSTRUMENT PANEL WIRE AND CONSOLE BOX WIRE (UNDER THE INSTRUMENT PANEL CENTER)
: GROUND POINTS
CODESEE PAGEGROUND POINTS LOCATION
IF36LEFT KICK PANEL
: SPLICE POINTS
CODESEE PAGEWIRE HARNESS WITH SPLICE POINTSCODESEE PAGEWIRE HARNESS WITH SPLICE POINTS
I1838INSTRUMENT PANEL WIREI2938CONSOLE BOX WIRE
SERVICE HINTS
WhereEverybodyKnowsYourName

94
INTERIOR LIGHT
21I
61E 91D10 1J 11F61F 21K1
4
1B
51H 10 1D61E11 1F 81H9
4
B6 IP 1
15
IP1 20
IJ IF
2 1 R
R
R
R
R
R±W
BR±W W±B
R±W
W±B
W±B
R
R R R R R
G±L
R±W
W±B
W±B
W±B
BR±W R±W
R±W
R±W
R±W
W±B
W±B
W±B
10A
GAUGE 7. 5A
RA DIO
NO. 210A
DOME
FROM POWER SOURCE SYSTEM
(
SEE PAGE 56 )
DIODE
DOOR OPEN
DETECTION SW RH
INTEGRATION
RELAY FADE OUT
CONTROL CIRCUIT1
R±W
D11
1
11
2
10
4
6
7 2
1D
8
B4
6 3 B4
4
1
4
1 A
1
B
1
A
2
B
3
IP 1
6
IF2
16
R±W P±B
L±W
R±W P±B
L±W
W±B
W±B
W±B
B7
(
USA )
( CA NADA )
DOOR KEY LOCK AND
UNLOCK SW LH
DOOR KEY LOCK AND
UNLOCK SW RH
DOOR OPEN
DETECTION SW LH D8 D7
D106 3
R±W
R±W
I16
,
AB
WhereEverybodyKnowsYourName

96
INTERIOR LIGHT
INTEGRATION RELAY (J/B NO. 1)(1B) 5±GROUND : ALWAYS APPROX. 12 VOLTS
(1D) 8±GROUND : CONTINUITY WITH FRONT LH DOOR OPEN
(1I) 6±GROUND : CONTINUITY WITH FRONT RH DOOR OPEN
D10, D11 DOOR OPEN DETECTION SW LH, RH
3±6 : CLOSED WITH DOOR OPEN
L 6 LUGGAGE COMPARTMENT LIGHT SW
1±GROUND : CLOSED WITH LUGGAGE COMPARTMENT DOOR OPEN
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
C12B28D1030L 730
C14A28D1130P2032
D 530I1430S1129
D 630I16A30V 531
D 730I16B30V 631
D 830L 630
: RELAY BLOCKS
CODESEE PAGERELAY BLOCKS (RELAY BLOCK LOCATION)
219ENGINE COMPARTMENT LEFT
422LEFT KICK PANEL (J/B NO.1 LEFT)
: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR
CODESEE PAGEJUNCTION BLOCK AND WIRE HARNESS (CONNECTOR LOCATION)
1B20ENGINE ROOM MAIN WIRE
1D20FRONT DOOR LH WIRE
1E20INSTRUMENT PANEL WIRE
1F20ROOF WIRE
1H
1I20COWL WIRE1J20COWL WIRE
1K
3A23INSTRUMENT PANEL WIRE3D23INSTRUMENT PANEL WIRE
: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS
CODESEE PAGEJOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)
IF236ENGINE WIRE AND COWL WIRE (R/B NO. 4)
IP138FRONT DOOR RH WIRE AND COWL WIRE (RIGHT KICK PANEL)
BX140FLOOR NO. 3 WIRE AND COWL WIRE (RIGHT KICK PANEL)
Bc140FLOOR NO. 3 WIRE AND FLOOR WIRE (UNDER THE LEFT SIDE OF REAR SEAT CUSHION)
: GROUND POINTS
CODESEE PAGEGROUND POINTS LOCATION
IF36LEFT KICK PANEL
IJ36RIGHT KICK PANEL
: SPLICE POINTS
CODESEE PAGEWIRE HARNESS WITH SPLICE POINTSCODESEE PAGEWIRE HARNESS WITH SPLICE POINTS
I 6B 240ROOF WIRE
I 738COWL WIREB 440FRONT DOOR LH WIRE
I15
38COWL WIRE
B 640FRONT DOOR RH WIREB 140ROOF WIREB 740FRONT DOOR RH WIRE
SERVICE HINTS
WhereEverybodyKnowsYourName

2
INTRODUCTION
This manual consists of the following 11 sections:No.
SectionDescription
A
INDEXIndex of the contents of this manual.
A
INTRODUCTIONBrief explanation of each section.
BHOW TO USE
THIS MANUALInstructions on how to use this manual.
CTROUBLE±
SHOOTINGDescribes the basic inspection procedures for electrical circuits.
DABBREVIATIONSDefines the abbreviations used in this manual.
E
GLOSSARY OF
TERMS AND
SYMBOLS
Defines the symbols and functions of major parts.
FRELAY LOCATIONSShows position of the Electronic Control Unit, Relays, Relay Block, etc.\
This section is closely related to the system circuit.
GELECTRICAL
WIRING ROUTINGDescribes position of Parts Connectors, Splice points, Ground points, etc.
This section is closely related to the system circuit.
HPOWER SOURCE
(Current Flow Chart)Describes power distribution from the power supply to various electrical
loads.
INDEXIndex of the system circuits.
I
SYSTEM CIRCUITS
Electrical circuits of each system are shown from the power supply through
ground points. Wiring connections and their positions are shown and
classified by code according to the connection method. (Refer to the
section, ªHow to use this manualº).
The ªSystem Outlineº and ªService Hintsº useful for troubleshoo\
ting are also
contained in this section.
JGROUND POINTSShows ground positions of all parts described in this manual.
KOVERALL
WIRING DIAGRAMProvides circuit diagrams showing the circuit connections.
WhereEverybodyKnowsYourName

109
WITH THE IGNITION SW TURNED ON, THE CURRENT FLOWS TO TERMINAL 7 OF THE INTEGRATION RELAY THROUGH GAUGE
FUSE. VOLTAGE IS APPLIED AT ALL TIMES TO TERMINAL (A)4 (USA), (B)11 (CANADA) OF THE INTEGRATION RELAY THROUGH THE
TAILLIGHT RELAY COIL, AND TO TERMINAL (A)5 (USA), (B)12 (CANADA) THROUGH THE HEADLIGHT RELAY COIL.
1. NORMAL LIGHTING OPERATION
TURN TAILLIGHT ON
WITH LIGHT CONTROL SW TURNED TO TAILLIGHT POSITION, A SIGNAL IS INPUT INTO TERMINAL (A)3 (USA), (B)10 (CANADA) OF
THE INTEGRATION RELAY. DUE TO THIS SIGNAL, THE CURRENT FLOWING TO TERMINAL (A)4 (USA), (B)11 (CANADA) OF THE RELAY
FLOWS TO TERMINAL (A)3 (USA), (B)10 (CANADA) " TERMINAL 3 OF THE LIGHT CONTROL SW "TERMINAL 4 " TO GROUND AND
TAILLIGHT RELAY CAUSES TAILLIGHT TO TURN ON.
TURN HEADLIGHT ON
WITH LIGHT CONTROL SW TURNED TO HEADLIGHT POSITION, A SIGNAL IS INPUT INTO TERMINALS (A)3 (USA). (B)10 (CANADA)
AND (A)6 (USA), (B)13 (CANADA) OF THE INTEGRATION RELAY. DUE TO THIS SIGNAL, THE CURRENT FLOWING TO TERMINAL (A)5
(USA), (B)12 (CANADA) OF THE RELAY FLOWS TO TERMINAL (A)6 (USA), (B)13 (CANADA) " TERMINAL 13 OF THE LIGHT CONTROL
SW " TERMINAL 4 " TO GROUND IN THE HEADLIGHT CIRCUIT, AND CAUSES TAILLIGHT AND HEADLIGHT RELAY TO TURN ON. THE
TAILLIGHT CIRCUIT IS SAME AS ABOVE.
2. LIGHT AUTO TURN OFF OPERATION
WITH LIGHTS ON AND IGNITION SW TURNED OFF (INPUT SIGNAL GOES TO TERMINAL 7 OF THE RELAY), WHEN DOOR ON DRIVER'S
SIDE IS OPENED (INPUT SIGNAL GOES TO TERMINAL 6 OF THE RELAY), THE RELAY OPERATES AND THE CURRENT IS CUT OFF
WHICH FLOWS FROM TERMINAL (A)4 (USA), (B)11 (CANADA) OF THE RELAY TO TERMINAL (A)3 (USA), (B)10 (CANADA) IN TAILLIGHT
CIRCUIT AND FROM TERMINAL (A)5 (USA), (B)12 (CANADA) TO TERMINAL (A)6 (USA), (B)13 (CANADA) IN HEADLIGHT CIRCUIT.
AS A RESULT, ALL LIGHTS ARE TURNED OFF AUTOMATICALLY.
HEADLIGHT RELAY 1±2 : CLOSED WITH LIGHT CONTROL SW AT HEAD POSITION OR DIMMER SW AT FLASH POSITION
TAILLIGHT RELAY 5±3 : CLOSED WITH LIGHT CONTROL SW AT TA I L OR HEAD POSITION
I16(A)(B) INTEGRATION RELAY
7±GROUND : APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION
6±GROUND : CONTINUITY WITH DOOR LH OPEN
(A) 4, (B) 11±GROUND: ALWAYS APPROX. 12 VOLTS
(A) 5, (B) 12±GROUND: ALWAYS APPROX. 12 VOLTS
(A) 6, (B) 13±GROUND: CONTINUITY WITH LIGHT CONTROL SW AT HEAD POSITION
(A) 3, (B) 10±GROUND: CONTINUITY WITH LIGHT CONTROL SW AT TA I L OR HEAD POSITION
D10 DOOR LOCK MOTOR, DOOR UNLOCK DETECTION SW AND DOOR OPEN DETECTION SW LH
3±6 : CLOSED WITH DOOR LH OPEN
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
C1528F 926I16B29 (CANADA)
D1030I16A29 (USA)
: RELAY BLOCKS
CODESEE PAGERELAY BLOCKS (RELAY BLOCK LOCATION)
219ENGINE COMPARTMENT LEFT
423LEFT KICK PANEL (J/B NO.1 LEFT)
: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR
CODESEE PAGEJUNCTION BLOCK AND WIRE HARNESS (CONNECTOR LOCATION)
1B20ENGINE ROOM MAIN WIRE
1D20FRONT DOOR LH WIRE
1J20COWL WIRE1K20COWL WIRE
: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS
CODESEE PAGEJOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)
IE136ENGINE WIRE AND COWL WIRE (R/B NO.4)
SYSTEM OUTLINE
SERVICE HINTS
WhereEverybodyKnowsYourName

1
2
X
X X
910
D4 I15
BLACK
107
LIQUID CRYSTAL INNER REAR VIEW MIRROR
2
1F
8 1B
5 B212
RY
R
R
R
W± B
10A
DOME
FROM POWER SOURCE
SYSTEM(
SEE PAGE 56 )
INNER MIRROR UNLOCK
WARNING SW
[IGNITION SW]
D4 I15
TO FRONT PERSONAL
LIGHT
DAY/NIGHT
SHIFT SW 1F
9
1I
15
9
10
1H
13
1J
1
1F
YW±B
1 2
D 4 DAY/NIGHT SHIFT SW
1 ± GROUND: ALWAYS APPROX.
12 VOLTS
I15 UNLOCK WARNING SW [IGNITION SW]
10±9: CLOSED WITH IGNITION KEY IN CYLINDER
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
D 430I1529
: 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
1F20ROOF WIRE
1H
1I20COWL WIRE
1J
: GROUND POINTS
CODESEE PAGEGROUND POINTS LOCATION
IF36LEFT KICK PANEL
: SPLICE POINTS
CODESEE PAGEWIRE HARNESS WITH SPLICE POINTSCODESEE PAGEWIRE HARNESS WITH SPLICE POINTS
B 240ROOF WIRE
SERVICE HINTS
WhereEverybodyKnowsYourName