ignition switch LEXUS SC400 1991 Service Repair Manual

STANDARD VALUE OF ECU TERMINAL
 

Terminals
 

Symbols
 

Wiring
color 

Condition
 

Standard
Value
 

W8±1
eW8±7
 

+B1
eE
 

R±L
eW±B
 

Wireless door lock main switch ON 

10 ~ 14 V 


W8±1eW8±7 


+B1eE 


R±LeW±B 

Wireless door lock main switch OFF
 

Below 1 V
 W8±2
eBody LSWD1 eBody L±W eBody Door lock knob of driver's door LOCK 8 ~ 10 V
 
y
Ground 
y
Ground 
y
Ground Door lock knob of driver's door UNLOCK Below 1 V
 W8±3 eBody LSWP eBody P±B eBody Door lock knob of assistant's door LOCK 8 ~ 10 V
 
y
Ground 
y
Ground 
y
Ground Door lock knob of assistant's door UNLOCK Below 1 V
 


W8 4
eBody
 


UL1
eBody
 


GW
eBody
 


Turn ignition switch ON,
Key operate switch Left and Right UNLOCK 


Below 1 V 


W8±4
eBody
Ground 


UL1
eBody
Ground 


G±W
eBody
Ground 


Turn ignition switch ON
Key operate switch Left or Right UNLOCK 


Below 1 V
    Except above mention 8 ~ 10 V
 

W8±5
eBody
 

L1
eBody
 

G±Y
eBody
 

Turn ignition switch, ON
Key operate switch Right LOCK 

Below 1 V
 


y
Ground 


y
Ground 


y
Ground 

Turn ignition switch ON,
Except above mention 

8 ~ 10 V
 W8±6
eBody KSW eBody Ye Body Ignition key insert key cylinder Below 1 V 

y
Ground 

y
Ground 

y
Ground 
Ignition key pull out key cylinder 
10 ~ 14 V 

W8±7
eBody
Ground
 

E
e Body
Ground
 

W±B
eBody
Ground
 

Always
 

Below 1 V
 

W8±9
eBody
 

LSWD2
eBody
 

W±L
eBody
 

Door lock knob of driver's door LOCK
 

8 ~ 10 V
 
y
Ground 
y
Ground 
y
Ground Door lock knob of driver's door UNLOCK Below 1 V
    Door open detection switch Left and Right ON 
 W8±10
eBody DSWD eBody G±L eBody Door open detection switch Left or Right ON Below 1 V
 
y
Ground 
y
Ground 
y
Ground Door open detection switch Left or Right OFF 
    Door open detection switch Left and Right OFF 10 ~ 14 V
±
BODY ELECTRICAL SYSTEM Wireless Door Lock Control SystemBE±453
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NGOK
INSPECTION PROCEDURE
1Check voltage between terminals LSWD1, LSWP and LSWD2 of ECU connector a\
nd body
ground.
C
OK
P1. Remove the rear seat and RH quarter trim panel.
2. Remove the ECU.
3. Turn ignition switch on.
Measure voltage between terminals LSWD1, LSWP
and LSWD2 of ECU connector and body ground, when
the respective door lock knob involved is pushed to the
lock side.
Voltage: 8 ± 10 V
Proceed to next circuit inspection shown on matrix chart
(See page BE±454).
Check and repair harness and connector between ECU and door unlock detec\
tion switch.
±
BODY ELECTRICAL SYSTEM Wireless Door Lock Control SystemBE±463
WhereEverybodyKnowsYourName

NGOK
INSPECTION PROCEDURE
1Check voltage between terminal UL1 of ECU connector and body ground.
C
OK
P1. Remove the rear seat and RH quarter trim panel.
2. Remove the ECU.
3. Turn ignition switch on.
Measure voltage between terminal UL1 of ECU connec-
tor and body ground.
Voltage: 8 ± 10 V
Proceed to next circuit inspection shown on matrix chart
(See page BE±454).
Check and repair harness and connector between ECU and door key lock and\
unlock switch.
±
BODY ELECTRICAL SYSTEM Wireless Door Lock Control SystemBE±465
WhereEverybodyKnowsYourName

NGOK
INSPECTION PROCEDURE
1Check voltage between terminal L1 of wireless door lock ECU connector and bod\
y ground.
C
OK
P1. Remove the rear seat and RH quarter trim panel.
2. Remove the ECU.
3. Turn ignition switch on.
Measure voltage between terminal L1 of ECU connec-
tor and body ground.
Voltage: 8 ± 10 V
Proceed to next circuit inspection shown on matrix chart
(See page BE±454).
Check and repair harness and connector between ECU and door key lock and\
unlock switch.
±
BODY ELECTRICAL SYSTEM Wireless Door Lock Control SystemBE±467
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WIRING DIAGRAM
Key Unlock Warning Switch Circuit
CIRCUIT DESCRIPTION
When the key is inserted in the ignition key cylinder the key unlock warning\
switch comes ON, and when the
key is not inserted switch is OFF.
When the key unlock warning switch is ON, the ECU operates the key confi\
nement prevention function.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
NGOK
Proceed to next circuit inspec-
tion shown on matrix chart (See
page
BE±454 ).
Check voltage between terminal KSW of
ECU connector and body ground.
Check and repair harness and connector
between ECU and key unlock warning
switch.
1
BE±468±
BODY ELECTRICAL SYSTEM Wireless Door Lock Control System
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Replacement of Fuse
HINT: If replacing the fuse, be sure to replace it with a fuse
with an equal amperage rating.
NOTICE:
1. Turn off all electrical components and the ignition switchbefore replacing a fuse. Do not exceed the fuse amperage
rating.
2. Always use a fuse puller for removing and inserting a fuse. Remove and insert straight in and out without
twisting. Twisting could force open the terminals too
much, resulting in a bad connection.
If a fuse continues to blow, a short circuit is indicated. The
system must be checked by a qualified technician.
HINT: The puller is located at Relay Block No. 2.
How to Inspect for System Inspection
This inspection precedure is a simple troubleshooting which
should be carried out on the vehicle during system operation
and is based on the assumption of system component
trouble (except for the wires and connectors, etc.).
Always inspect the trouble taking the following items into con-
sideration.
wGround point fault
w Open or short circuit of the wire harness
w Connector or terminal connection fault
w Fuse or fusible link fault
NOTICE:
1. This is an on±vehicle inspection during system
operation. Therefore, inspect the trouble with due regard
for safety.
2. If connecting the battery directly, be careful not to short circuit, and select the applicable voltage.
BE±4±
BODY ELECTRICAL SYSTEM General Information
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PRECAUTIONS
Take care to observe the following precautions when performing inspection\
s or removal and replacement
of body electrical related parts.
1. SRS AIR±BAG SYSTEM

Work must be started approx. 20 seconds after the ignition is set to the Loc\
k position and the negative
(±) terminal cable is disconnected from the battery. (See page AB±2)

When disconnecting any of the connectors in the SRS AIR±BAG system, be su\
re to Lock the ignition
switch and disconnect the battery negative (±) terminal first. Since the connectors are twin \
lock type
connectors, disconnect the connectors only after releasing the first stage lock.

When connecting SRS AIR±BAG system connectors, be sure to lock them secur\
ely. (If the connectors
are not locked securely, the system may not operate when needed.)

Always store the steering wheel pad with the pad surface facing upward. (Stor\
ing the pad with its
metallic surface up may lead to a serious accident if the air bag inflates for s\
ome reason.)

When installing the spiral cable, be sure the vehicle is in the straight ahe\
ad condition and confirm that
the spiral cable is in the neutral position when it is installed. (See pag\
e BE±40)

INFORMATION LABELS (NOTICE) are attached to the periphery of the air bag componen\
ts. Follow
the NOTICE.
2. MICRO COMPUTER PRESET DRIVING POSITION SYSTEM
Power Seat Control System
Power Mirror Control System
Power Tilt and Telescopic Steering System

If the battery negative (±) terminal is disconnected, the preset driv\
ing positions stored in memory are
erased, so be sure to note the positions and reset them after the battery termi\
nal is reconnected.
3. AUDIO SYSTEM

If the battery negative (±) terminal is disconnected, the preset AM, F\
M 1 and FM 2 stations stored in
memory are erased, so be sure to note the stations and reset them after the battery terminal is
reconnected.

If the battery negative (±) terminal is disconnected, the ºANTI±\
THEFT SYSTEMº will operate when
the terminal is reconnected, but the radio, tape player and CD player will \
not operate. Be sure to input
the correct ID number so that the radio, tape player and CD player can be o\
perated again.
±
BODY ELECTRICAL SYSTEM PrecautionsBE±7
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Replacement of Relays
REPLACEMENT OF RELAY IN RELAY
BLOCK NO. 1, NO. 4 and NO. 5
1. REMOVE FOLLOWING PARTS:(See page BO±112)
(a) No. 1 under cover.
(b) Door scuff plate.
(c) Floor carpet.
2. REMOVAL AND INSTALLATION OF RELAY
(a) Remove the junction block No. 1 set bolts.
(b) Disconnect connectors.
(c) Separate the relay block No. 4 and No. 5 from the junction block No. 1.
(d) For installation follow the removal procedure in reverse.
Replacement of Relay Block No. 2
(A)
REPLACEMENT OF RELAY BLOCK NO. 2
(A) IN RELAY BLOCK NO. 2
1. REMOVE RELAY BLOCK NO. 2 (A)
(a) Remove the battery. CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ºLOCKº position and negative (±) terminal
cable is disconnected from the battery.
(b) Remove the relay block No. 2 cover.
(c) Pry loose two locking lugs and remove the nut.
2. INSTALL RELAY BLOCK NO. 2 (A) For installation follow removal procedure in reverse.
BE±16
±
BODY ELECTRICAL SYSTEM Power Source
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REPLACEMENT OF RELAY BLOCK NO. 2
(B) IN RELAY BLOCK NO. 2
1. REMOVE RELAY BLOCK NO. 2 (B)
(a) Disconnect the battery terminals.CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ºLOCKº position and negative (±) terminal
cable is disconnected from the battery.
(b) Remove the relay block No. 2 cover.
(c) Remove the relay block No. 2 lower cover.
2. INSTALL RELAY BLOCK NO. 2 (B) For installation follow the removal procedure in reverse.
±
BODY ELECTRICAL SYSTEM Power SourceBE±17
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Inspection of Power Source Circuit
INSPECTION OF JUNCTION BLOCK NO. 1
1. INSPECT FUSE CIRCUITRemove the fuse from the junction block and inspect the con-
nector on junction block side as shown.
FuseCheck forTester connectionConditionSpecified value
IGNVoltage1±GroundIgnition switch turned to ONBattery voltage
ST
g
4±GroundIgnition switch turned to START
yg
WIPER5±GroundIgnition switch turned to ON
HTR8±Ground
g
ENGINE9±Ground
RADIO NO. 211±GroundIgnition switch turned to ACC or ON
CIG14±Ground
g
STOP15±GroundConstant
TURN18±GroundIgnition switch turned to ON
MIR HTR20±GroundIgnition switch turned to ON and defogger
switch turned to ON
PANEL21±GroundLight control switch turned to TAIL or HEAD
and *Engine Running
ECU±B27±GroundConstant
GAUGE29±GroundIgnition switch turned to ON
ECU±IG32±Ground
g
TAIL33±GroundLight control switch turned to TAIL or HEAD
and *Engine Running
DOOR35±GroundConstant
IG SW38±Ground
POWER39±Ground
If the circuit is not as specified, refer to BE±15 wiring diagram
and inspect the circuits connected to other parts.
BE±20
±
BODY ELECTRICAL SYSTEM Power Source
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