light LEXUS SC400 1991 Service Owners Manual

Check stop light operation.NG
OK OK
NG Check stop light circuit
(See page
BE±64).
Proceed to next circuit inspection
shown on matrix chart
(See page
BE±276).
Check voltage between terminals STOP
of ECU connector and body ground.
Check and repair harness and connec-
tor between ECU and stop light switch.
WIRING DIAGRAM
Stop Light Circuit
CIRCUIT DESCRIPTION
The stop light switch sends a brake ON of Off signal to the ECU. When the ECU receives a brake ON signal
it prohibits return of the seat.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
BE±298±
BODY ELECTRICAL SYSTEM Power Seat Control System (Driver's Seat)
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OKNG
NGOK
INSPECTION PROCEDURE
1Check stop light operation.
Check that the stop light comes on when the brake pedal is depressed, and turn\
s off when the pedal
is released.C
Check stop light circuit. (See page BE±64).
2Check voltage between terminal STOP of ECU connector and body ground.
C
OK
Hint
PRemove ECU with connectors still connected.
Measure voltage between terminal STOP of ECU and
body gr ound when the brake pedal is depressed and re-
leased.
Brake pedal Voltage
Depressed 10 ± 14 V Released Below 1 V
Proceed to next circuit inspection shown on matrix chart
(See page BE±276).
Check and repair harness and connector between
ECU and stop light switch.
±
BODY ELECTRICAL SYSTEM Power Seat Control System (Driver's Seat)BE±299
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OKNG
NGOK
INSPECTION PROCEDURE
1Check the shift position indicator.
Check that P lights up on the shift indicator when P range is shifted in\
to, and that P is OFF when
shiftin
g into another range.
C
Check shift position indicator circuit (See page BE±141).
2Check voltage between terminal P of ECU connector and body ground.
C
OK
PRemove ECU with connectors still connected.
(1) Turn ignition switch ON.
(2) Measure voltage between terminal P of ECU con-nector and body ground when the shift lever is posi-
tioned to the following ranges.
Shift range
P
1
0
Other than PVoltage
10 ± 14 V
Below 1 V
Proceed to next circuit inspection shown on matrix chart
(See page BE±276).
Check and repair harness and connector between
ECU and connector.
±
BODY ELECTRICAL SYSTEM Power Seat Control System (Driver's Seat)BE±301
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WIRING DIAGRAM
Door Open Detection Switch Circuit
CIRCUIT DESCRIPTION
The door open detection switch comes ON when the door is opened and goes OFF when the door is closed.
Furthermore the door open detection switch circuit has terminal +B connected inside \
the theft deterrent and door
lock ECU, battery positive voltage is applied to terminal DSWD of the wirele\
ss door lock ECU when all doors
are closed, i.e., when the door open detection switch of all doors are O\
FF.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
NG OK
Check open door warning light
circuit (See page
BE±118).
Check operation of open door warning
light
Check voltage between terminal DSWD
of ECU connector and body ground. Proceed to next circuit inspec-
tion show on matrix chart (See
page
BE±454 ).
Check and repair harness and connector
between ECU and door open detection
switch.;
1
2
BE±470±
BODY ELECTRICAL SYSTEM Wireless Door Lock Control System
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OKNG
NGOK
INSPECTION PROCEDURE
1Check operation of open door warning light.
Check that open door warning light comes on when each door is opened, and goes\
off when all doors
are closed.C
Check open door warning light circuit (See page
BE±118 ).
2Check voltage between terminal DSWD of ECU connector and body ground.
C
OK
P1. Remove the rear seat and RH quarter trim panel.
2. Remove the ECU.
3. Wireless door lock main switch on.
Measure voltage between terminal DSWD of ECU con-
nector and body ground, when all doors are closed.
Voltage: 10 ± 14 V
Proceed to next circuit inspection shown on matrix chart
(See page BE±454).
Check and repair harness and connector between ECU and door open detecti\
on switch.
±
BODY ELECTRICAL SYSTEM Wireless Door Lock Control SystemBE±471
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GENERAL INFORMATION
Wiring Color Code
Wire colors are indicated by an alphabetical code.
B = Black L = Blue R = Red
BR = Brown LG = Light Green V = Violet
G = Green O = Orange W = White
GR = Gray P = Pink Y = Yellow
The first letter indicates the basic wire color and the second
letter indicates the color of the stripe.
Connector
1. PIN NUMBERS OF FEMALE CONNECTORNumbered in order from upper left to lower right.
2. PIN NUMBERS OF MALE CONNECTOR
Numbered in order from upper right to lower left.
HINT: When connectors with different of the same number of
terminals are used with the same parts, each connector
name (letter of the alphabet) and pin number is specified.
3. DISTINCTION OF MALE AND FEMALE CONNECTORS Male and female connectors are distinguished by shape of
their internal pins.
(a) All connectors are shown from the open end, and thelock is on top.
(b) To pull apart the connectors, pull on the connector itself, not the wires.
HINT: Check to see what kind of connector you are discon-
necting before pulling apart.
BE±2
±
BODY ELECTRICAL SYSTEM General Information
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Check for Voltage
(a) Establish conditions in which voltage is present at thecheck point.
Example:
(A)±Ignition SW on
(B)±Ignition SW and SW 1 on
(C)±Ignition SW, SW 1 and Relay on (SW 2 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 bulb instead
of a voltmeter.
Check for Continuity and Resistance
(a) Disconnect the battery terminal or wire so there is no voltage between the check points.
(b) Connect the two leads of an ohmmeter to each of the check points.
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.
HINT: Specifications may vary depending on the type of tes-
ter, so refer to the tester's instruction manual before perform-
ing the inspection.
Check LED (Light Emitting Diode) in the same manner as that
for diodes.
HINT:
w Use a tester with a power source of 3 V or greater to
overcome the circuit resistance.
w If a suitable tester is not available, apply battery voltage
and check that the LED lights up.
±
BODY ELECTRICAL SYSTEM General InformationBE±5
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(c) Use a volt/ohmmeter with high impedance (10 k/Vminimum) for troubleshooting of the electrical circuit.
Check the Bulb
(a) Remove the bulb.
(b) There s hould be continuity between the respective
terminals of the bulb together with a certain amount of
resistance.
(c) Apply the two leads of the ohmmeter to each of the terminals.
(d) Apply battery voltage and check that the bulb light up.
Check for Short Circuit
(a) Remove the blown fuse and eliminate all loads from the fuse.
(b) Connect a test bulb in place of the fuse.
(c) Establish conditions in which the test bulb 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) D i s c onnect and reconnect the connectors while
watching the test bulb. The short lies between the
connector where the test bulb stays lit and the connector
where the bulb goes out.
(e) Find the exact location of the short by lightly shaking the problem wire along the body.
BE±6
±
BODY ELECTRICAL SYSTEM General Information
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PREPARATION
SST (SPECIAL SERVICE TOOLS)
IllustrationPart No.Part NameNote
09213±31021
Crankshaft Pulley
Puller
For removing steering wheel
RECOMMENDED TOOLS
IllustrationPart No.Part NameNote
09082±00015TOYOTA
Electrical Tester
09041±0030Torx Driver
T30
For removing and installing steering wheel pad and
power window motor
09042±00010Torx Socket
T30For removing and installing steering wheel pad and
power window motor
EQUIPMENT
Part NameNote
Voltmeter
Ammeter
Ohmmeter
Test lead
ThermometerWater temperature sender gauge, Engine oil level, Warning switch, Seat heater
SyphonBrake fluid level warning switch
Oil bathEngine oil level warning switch
Bulb (1.4 W)Coolant level warning ECU
Bulb (3.4 W)Fuel sender, gauge, Seat belt warning relay
Bulb (21 W)Turn signal flasher relay
Dry cell batteryFuel sender gauge
Heat lightSeat heater
Hexagon wrench (6 mm)Power seat
BE±8±
BODY ELECTRICAL SYSTEM Preparation
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Description
The power source supplies power to each of the vehicle's electrical devices. It is composed of the battery, fuses
and relays, which are located centrally at relay block No. 2 and relay block No. 6 i\
n the engine compartment
and junction block No. 1 relay block No. 4 and relay block No. 5 in the \
cabin near the driver's feet.
Related systems for each Fuse
No.Part NameRelated Systems or Parts
1IGN
Charging System
AIR±BAG System1IGN
Engine
2ST
Starter
3WIPER
Wiper and Washer System
4HTR
Defogger System
A/C System
5ENGINE
Charging System
6RADIO NO. 2
Audio System
Power Mirror System

Cigarette Lighter
A/C System
7CIG
Combination Meter System
AIR±BAG System7CIG
Shift Lock System
Theft Deterrent System

TEL System
8STOP
Stop Light System
Cruise Control System
9TURN
Turn Signal and Hazard
Warning Light System
Cornnering Light System
10MIR HTR
Mirror Heater System
11PANEL
Illumination Light System
12ECU±B
Combination Meter System
AIR±BAG System

Combination Meter System
ECT System
13GAUGE
Back±Up Light
Transmission Indicator

Light Failare Sensor
ABS and TRAC

Power Seat System
Door Lock Control System

TEL System
Shift Lock System
14ECU±IG
Radiator Fan
Auto Antenna

Electric Tension Reducer System
Power Steering

Auto±Tilt away Steering
Cruise Control System
15TAIL
Taillight System
Side Marker15TAIL
Clearance Light
16DOOR
Power Seat System
Luggage Door Opener16DOOR
Door Lock Control System
Fuel Lid Opener System
17IG SWUpstream of ECU±IG, ENGINE, WIP, HTR, TURN, GAUGE, and ST Fuse
18PWR
Power Window System
Sliding Roof System
19ABS NO. 1
ABS and TRAC
20AM1Upstream of MIR HTR, TAIL, PANEL, STOP, ECUA±B, DOOR and PWR Fuse
21ALTUpstream of DEF, HTR, AM1, and ABS No. 1 Fuse
BE±18±
BODY ELECTRICAL SYSTEM Power Source
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