TOYOTA SUPRA 1997 Service Repair Manual

A INTRODUCTION
2
This manual consists of the following 11 sections:
A
B
C
D
E
F
G
H
I
J
K
No.
GROUND POINTS
OVERALL
ELECTRICAL
WIRING DIAGRAM SYSTEM CIRCUITSINDEX
POWER SOURCE
(Current Flow Chart) ELECTRICAL
WIRING ROUTING RELAY LOCATIONS GLOSSARY OF
TERMS AND
SYMBOLS ABBREVIATIONS TROUBLE-
SHOOTING HOW TO USE
THIS MANUAL INTRODUCTION INDEX
Section Description
Index of the contents of this manual.
Brief explanation of each section.
Instructions on how to use this manual.
Describes the basic inspection procedures for electrical circuits.
Defines the abbreviations used in this manual.
Defines the symbols and functions of major parts.
Shows position of the Electronic Control Unit, Relays, Relay Block, etc.
This section is closely related to the system circuit.
Describes position of Parts Connectors, Splice points, Ground points, etc.
This section is closely related to the system circuit.
Describes power distribution from the power supply to various electrical
loads.
Index of the 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, How to use this manualº).
The System Outlineº and Service Hintsº useful for troubleshooting are
also contained in this section.
Shows ground positions of all the parts described in this manual.
Provides circuit diagrams showing the circuit connections.

3
HOW TO USE THIS MANUAL B
This manual provides information on the electrical circuits installed on vehicles
by dividing them into a circuit for each system.
The actual wiring of each system circuit is shown from the point where the power
source is received from the battery as far as each ground point. (All circuit
diagrams are shown with the switches in the OFF position.)
When troubleshooting any problem, first understand the operation of the circuit
where the problem was detected (see System Circuit section), the power source
supplying power to that circuit (see Power Source section), and the ground
points (see Ground Points section). See the System Outline to understand the
circuit operation.
When the circuit operation is understood, begin troubleshooting of the problem
circuit to isolate the cause. Use Relay Location and Electrical Wiring Routing
sections to find each part, junction block and wiring harness connectors, wiring
harness and wiring harness connectors, splice points, and ground points of each
system circuit. Internal wiring for each junction block is also provided for better
understanding of connection within a junction block.
Wiring related to each system is indicated in each system circuit by arrows
(from
,to ). When overall connections are required, see the Overall Electrical
Wiring Diagram at the end of this manual.

* The system shown here is an EXAMPLE ONLY. It is different to the actual
circuit shown in the SYSTEM CIRCUITS SECTION.
4
B HOW TO USE THIS MANUAL

5
B
I :Junction Block (The number in the circle is the
J/B No. and the connector code is shown beside
it). Junction Blocks are shaded to clearly
separate them from other parts .
A :System Title
B :Indicates a Relay Block. No shading is used and only the
Relay Block No. is shown to distinguish it from the J/B.
Example: 1 Indicates Relay Block No. 1.
C :Indicates the connector to be connected to a
part (the numeral indicates the pin No.)
Explanation of pin use.J :Indicates the wiring color.
Wire colors are indicated by an alphabetical code.
B = Black
BR = Brown
G = Green
GR = GrayL = Black
LG = Light Green
O = Orange
P = PinkR = Red
V = Violet
W = White
Y = Yellow
The first letter indicates the basic wire color and the second
letter indicates the color of the stripe.
D :Connector Color Connectors not indicated are milky
white in color:
E :( ) is used to indicate different wiring and connector, etc.
when the vehicle model, engine type, or specification is
different.
F :Indicates related system.
G :Indicates the wiring harness and wiring harness
connector. The wiring harness with male terminal is
shown with arrows ( ).
Example: L - Y
K :Indicates a wiring Splice Point (Codes are Eº for
the Engine Room, Iº for the Instrument Panel,
and Bº for the Body).
Example:
The Location of Splice Point I 5 is indicated by the shaded
section.
L :Page No.
M :Indicates a shielded cable.
Example:N :Indicates a ground point.
The first letter of the code for each ground point(s) indicates
the component's location, e.g. Eº for the Engine
Compartment, Iº for the Instrument Panel and Surrounding
area, and Bº for the Body and Surrounding area.
The first letter of the code for each wiring harness and wiring
harness connector(s) indicates thecomponent's location, e.g,
Eº for the Engine Compartment, Iº for the Instrument Panel
and Surrounding area, and Bº for the Body and Surrounding
area.
When more than one code has the first and second letters in
common, followed by numbers (e.g, IH1, IH2), this indicates
the same type of wiring harness and wiring harness connector.
P :When 2 parts both use one connector in common, the parts
connector name used in the wire routing section is shown in
square brackets [ ]. O :Indicates the pin number of the connector.
The numbering system is different for female and male
connectors.
H :Represents a part (all parts are shown in sky
blue). The code is the same as the code used in
parts position.
3B indicates
that it is inside
Junction Block
No. 3. v
v The pins shown are only for the highest grade, or only
include those in the specification.
lower rightlower left
(blue) (yellow)

6
B 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 MANUAL UPº OPERATION BY MASTER SW
HOLDING MANUAL SW (DRIVER'S) ON UPº POSITION LOCATED IN POWER WINDOW MASTER SW, THE CURRENT FLOWS TO TERMINAL 5 OF THE POWER WINDOW CON-
TROL 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 TERMI-
NAL 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 MANUAL DOWNº OPERATION, CURRENT FLOWS IN THE REVERSE DIRECTION BECAUSE THE TERMINALS WHERE IT FLOW ARE CHANGED).
2. DRIVER'S WINDOW AUTO DOWNº OPERATION BY MASTER SW
ONCE THE AUTO DOWNº BUTTON OF THE MASTER SW IS PUSHED, THE CURRENT FLOW 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 UPº 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 UPº, 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 LOCKº POSITION, THE CIRCUIT IS OPENED AND STOPPED THE MOTOR ROTA-
TION.
(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 THE IGNITION SW AT ON POSITION
5-GROUND: APPROX. 12 VOLTS WITH THE IGNITION SW AT ON POSITION AND THE MASTER SW AT UP POSITION
8-GROUND: APPROX. 12 VOLTS WITH THE IGNITION SW AT ON POSITION AND THE MASTER SW AT AUTO DOWN POSITION
9-GROUND: APPROX. 12 VOLTS WITH THE IGNITION SW AT ON POSITION AND THE MASTER SW AT DOWN OR AUTO DOWN POSITION
P 4 POWER WINDOW MASTER SW
4-GROUND: ALWAYS CONTINUITY
3-GROUND: APPROX. 12 VOLTS WITH THE IGNITION SW AT ON POSITION
WINDOW LOCK SW
OPEN WITH THE WINDOW LOCK SW AT LOCK POSITION
: PARTS LOCATION
CODE SEE PAGE CODE SEE PAGE CODE SEE PAGE
P221P421P621
P321P521
: RELAY BLOCKS
CODE SEE PAGE RELAY BLOCK (RELAY BLOCK LOCATION)
116 R/B NO. 1 (INSTRUMENT PANEL LEFT)
: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR
CODE SEE PAGE JUNCTION BLOCK AND WIRE HARNESS (CONNECTOR LOCATION)
3814 J/B NO. 3 AND COWL WIRE (INSTRUMENT PANEL LEFT SIDE)
: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS
CODE SEE PAGE JOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)
ID126 FRONT DOOR RH WIRE AND COWL WIRE (RIGHT KICK PANEL)
IH126 FRONT DOOR LH WIRE AND COWL WIRE (LEFT KICK PANEL)
: GROUND POINTS
CODE SEE PAGE GROUND POINT LOCATION
IC24 COWL LEFT
: SPLICE POINTS
CODE SEE PAGE WIRE HARNESS WITH SPLICE POINTS CODE SEE PAGE WIRE HARNESS WITH SPLICE POINTS
I 524 COWL WIREQ
R
S
T
U
V
W
X
SERVICE HINTS
SYSTEM OUTLINE

7
B
Q :Explains the system outline.
R :Indicates values or explain the function for reference during troubleshooting.
S :Indicates the reference page showing the position on the vehicle of the parts in the system circuit.
Example: Part P 4º (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 order in
parts starting with the letter.
Example: P 4
HINTS:
Part is 4th in order
Power Window Master SW
Junction connector (code: J1 to J19) in this manual
include a short terminal which is connected to a
number of wire harnesses. Always perform inspec-
tion with the short terminal installed. (When instal-
ling the wire harnesses, the harnesses can be con-
nected to any position within the short terminal
grouping. Accordingly, in other vehicles, the same
position in the short terminal may be connected to
a wire harness from a different part.)
Wire harness sharing the same short terminal
grouping have the same color. T :Indicates the reference page showing the position on the vehicle of Relay Block Connectors in the system
circuit.
Example: Connector 1º is described on page 16 on this manual and is installed on the left side of the
instrument panel.
U :Indicates the reference page showing the position on the vehicle of J/B and Wire Harness in the system
circuit.
Example: Connector 3Bºconnects the Cowl Wire and J/B No. 3. It is described on page 14 of this manual,
and is installed on the instrument panel left side.
V :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 ID1ºconnects the front door RH wire (female) and cowl wire (male). It is described
on page 26 of this manual, and is installed on the right side kick panel.
W :Indicates the reference page showing the position of the ground points on the vehicle.
Example: Ground point ICº is described on page 24 of this manual and is installed on the cowl left side.
X :Indicates the reference page showing the position of the splice points on the vehicle.
Example: Splice point I 5º is on the Cowl Wire Harness and is described on page 24 of this manual.

8
B HOW TO USE THIS MANUAL
The Current Flow Chartº section, describes which parts each power source (fuses, fusible links, and circuit
breakers) transmits current to. In the Power Source circuit diagram, the conditions when battery 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.
* The system shown here is an EXAMPLE ONLY. It is different to the actual circuit shown in the SYSTEM CIRCUITS SECTION.
H 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 shown the parts to which each electrical source outputs current.
POWER SOURCE

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

10
C TROUBLESHOOTING
(a) Disconnect the battery terminal or wire so there is no
voltage between the check points.
(b) Contact the two leads of an ohmmeter to each of the
check point.
If the circuit has diodes, reverse the two leads and check
again.
When contacting the negative lead to the diode positive side
and the positive lead to the negative side, there should be
continuity.
When contacting the two leads in reverse, there should be
no continuity.
(c) Use the volt/ohmmeter with high impedance (10 kW/V
minimum) for troubleshooting of the electrical circuit.
CONTINUITY AND RESISTANCE CHECK VOLTAGE CHECK
(a) Establish conditions in which voltage is present at the
check point.
Example:

A- Ignition SW on

B- Ignition SW and SW 1 on

C- Ignition SW, SW 1 and Relay on (SW2 off)
(b) Using a voltmeter, connect the negative lead to a good
ground point or negative battery terminal, and the
positive lead to the connector or component terminal.
This check can be done with a test light instead of a
voltmeter.

11
C
(a) Remove the blown fuse and disconnect all loads of the
fuse.
(b) Connect a test light in place of the fuse.
(c) Establish conditions in which the test light comes on.
Example:
A - Ignition SW on
B - Ignition SW and SW 1 on
C - Ignition SW, SW 1 and Relay on (Connect the
Relay) and SW 2 off (or Disconnect SW 2)
(d) Disconnect and reconnect the connectors while watching
the test light.
The short lies between the connector where the test
light stays lit and the connector where the light goes
out.
(e) Find the exact location of the short by lightly shaking
the problem wire along the body.
(a) Do not open the cover or the case of the ECU unless
absolutely necessary. (If the IC terminals are touched,
the IC may be destroyed by static electricity.)
(b) When replacing the internal mechanism (ECU part) of
the digital meter, be careful that no part of your body
or clothing comes in contact with the terminals of
leads from the IC, etc. of the replacement part (spare
part).
CAUTION: FINDING A SHORT CIRCUIT
DISCONNECTION OF MALE AND FEMALE
CONNECTORS
To pull apart the connectors, pull on the connector itself, not
the wire harness.
HINT: Check to see what kind of connector you are
disconnecting before pulling apart.