key LEXUS SC400 1991 Service User Guide

HOW TO PROCEED WITH TROUBLESHOOTING
Perform troubleshooting in accordance with the procedure on the following page.\

CUSTOMER PROBLEM ANALYSIS
Using the customer problem analysis check sheet for reference, ask the c\
ustomer in as much detail as
possible about the problem.
\b PROBLEM SYMPTOM CONFIRMATION,  SYMPTOM SIMULATION.
Confirm the problem symptoms. If the problem does not reappear, be sure to simulate the problem using
the ºProblem Simulation Methodsº.
When checking the problem symptoms, pay attention to the following points to\
accurately define the symp-
toms and the extent of the problem:
For ºNot Functioningº problems:
(1) Is the problem only in one part (e.g. ºreclining onlyº), or ever\
ything?
(2) Is the problem only for manual operation, only for position return opera\
tion, or for both manual and position return operation?
(3) Is tilt, telescopic and outer mirror operation normal?
(4) Does the problem occur with the ignition key inserted, or not inserted?
 MATRIX CHART OF PROBLEM SYMPTOMS
Confirm the order of inspection on the matrix chart for the particular problem symptom involved. For ºNot
Functioningº problems, pay attention to the points in \b. to find out the specifics of the problem, then choose
the most appropriate problem symptom from among those listed on the matr\
ix chart, and proceed with trou-
bleshooting accordingly.
 CIRCUIT INSPECTION
Proceed with diagnosis of each circuit in accordance with the inspection\
order confirmed in .
Determine whether the cause of the problem is in the sensor, actuators, wire harness and connectors, or
the ECU.
 POSITION SENSOR CHECK
This function checks that the signal from each position sensor is correctly input into\
the ECU when the
manual switch is turned ON. The instructions for this diagnosis are included in\
the flow chart for the position
sensor circuit.
 REPAIR
After the cause of the problem is located, perform repairs by following the i\
nspection and replacement pro-
cedures is this manual.
 CONFIRMATION TEST
After completing repairs, confirm that the problem is eliminated and that tilt, telescopic and outer mirror
operation is normal.
BE±268
±
BODY ELECTRICAL SYSTEM Power Seat Control System (Driver's Seat)
WhereEverybodyKnowsYourName

CUSTOMER PROBLEM ANALYSIS CHECK SHEET
POWER SEAT Check Sheet
Inspector 's
Name :
 


 


 

Registration No.
 


 

Customer 's Name
 


 

Registration Year
 

//
 


 


 

Frame No.
 


 

Date Vehicle
Brought In 

//
 

Odometer Reading
 

Km
Miles
 

Condition of
Problem
 

Date Problem
Occurrence\
 

\
//
 



Problem
Occurrence 



How Often does
Problem Occur?
\
 





Continuous
Intermittent ( times a day)
 




 






Manual Function
does not operate
\
 



\



Slide
Front Vertical

Rear Vertical
Reclining
Lumbar Support
 








Symptoms
 










Return Function
does not operate\
 







\



Slide
Front Vertical

Rear Vertical
Reclining

Does not operate in any conditions

Only with key inserted

Only with key not inserted

Only with memory & return switch 1 or 2
 \
 \

Memory function does not operate. 


\
 
\

\


Position return function does not stop when brake pedal is depressed.
For ªReturn function does not operateº malfunctions, check the ret\
urn operation of the items below.
 


Ch k It
 

Tilt & Telescopic
\
 

\


OK
NG
 


Check Item 

Outer Mirror
\
 

\


OK
NG
BE±270±
BODY ELECTRICAL SYSTEM Power Seat Control System (Driver's Seat)
WhereEverybodyKnowsYourName

DESCRIPTION
The door lock control system has a key±interlocked door lock and unlock \
function and a key±confinement pre-
vention function. All doors can be locked and unlocked simultaneously by\
key operation at the front right or left
door (the key needs to be operated twice to unlock the doors at the driver's door). If the door lock operation is
performed when one of the doors is open and the ignition key inserted in\
the key cylinder, doors are unlocked
automatically to prevent the ignition key from being left inside the veh\
icle. The luggage compartment door can
be opened by electromagnetic opener.
For the function of component parts of this system, refer to the circuit\
description in circuit inspection.
PARTS LOCATION
BE±362±
BODY ELECTRICAL SYSTEM Door Lock Control System
WhereEverybodyKnowsYourName

DESCRIPTION
The door lock control system has a key±interlocked door lock and unlock f\
unction and a key±confinement pre-
vention function. All doors can be locked and unlocked simultaneously by\
key operation at the front right or left
door (the key needs to be operated twice to unlock the doors at the driver's door). If the door lock operation is
performed when one of the doors is open and the ignition key inserted in\
the key cylinder, doors are unlocked
automatically to prevent the ignition key from being left inside the veh\
icle. The luggage compartment door can
be opened by electromagnetic opener.
For the function of component parts of this system, refer to the circuit\
description in circuit inspection.
PARTS LOCATION
BE±362±
BODY ELECTRICAL SYSTEM Door Lock Control System
WhereEverybodyKnowsYourName

HOW TO PROCEED WITH TROUBLESHOOTING
Perform troubleshooting in accordance with the procedure on the following page.\

CUSTOMER PROBLEM ANALYSIS
Using the customer problem analysis check sheet for reference, ask the c\
ustomer in as much detail as
possible about the problem.
 PROBLEM SYMPTOM CONFIRMATION,  SYMPTOM SIMULATION
Confirm the problem symptoms. If the problem does not reappear, be sure to simulate the problem using
ºProblem Simulation Methodº.
For example, if the malfunction involves failure of the lock or unlock duri\
ng operation of the Door Lock Con-
trol Switch, check if lock and unlock operation of the door using the key is\
normal or abnormal, and also
check if key confinement prevention function and luggage compartment door ope\
ner function are normal
or not. And having fully checked the extent of the malfunction.
 MATRIX CHART OF PROBLEM SYMPTOMS
Confirm the order of inspection for each applicable problem symptom on t\
he matrix chart.
 CIRCUIT INSPECTION
Proceed with diagnosis of each circuit in accordance with the inspection order \
confirmed in . Judge
whether the cause of the problem is in the sensor, wire harness and connectors, or the ECU.
 REPAIR
When the cause of the problem is found in , perform repairs.
 CONFIRMATION TEST
After completing repairs, confirm that the problem is eliminated and that all functions of the door lock control
system are normal.
BE±364
±
BODY ELECTRICAL SYSTEM Door Lock Control System
WhereEverybodyKnowsYourName

CUSTOMER PROBLEM ANALYSIS CHECK SHEET
\
 
\

\
DOOR LOCK CONTROL System Check Sheet
Inspector 's
Name :
   Registration No. 
 

Customer 's Name
 


 

Registration Year
 

//
 


 


 

Frame No.
 


 


Date Vehicle
Brought In 

//
 

Odometer Reading
 


km
Miles
 Date of Problem Occurrence\
 \
// 



Frequency of Problem Occurrence
\
 
\


\

\


Constant  Sometimes ( times/per day, month)
 Once only
 

Conditions at
Ti f P bl
 

Weather
\
 
\

\

Fine  Cloudy Rainy  Snowy
 Various/Others
 



Time of Problem
Occurrence 



Outdoor
Temperature
\
 
\


\


Hot  Warm  Cool
 Cold (Approx. 5F ( 5C))
 






 







Malfunction in Door Lock/Unlock
Operation Using Door Lock
Control Switch
 







Driver's side door lock
control switch
 







Driver's side door
 Passenger's side door
 






 






 







Passenger's side door lock
control switch
 







Driver's side door
 Passenger's door
 






 







Malfunction in Door Lock/Unlock
Operation Using Key.
 







Driver's side door key
operated switch
 







Driver's side door
 Passenger's side door
 




 




 





Passenger's side door key
operated switch
 





Driver's side door
 Passenger's side door
 




 




\
 
\


\

\


2±operation unlock function of driver's side door key operated
switch.
 \
 \
 Malfunction in Key Confinement Prevention Function.
 \
 \
 Malfunction in Luggage Compartment Door Opener Function.
 


\
 
\

\


Others
Problem Symptom
BE±366±
BODY ELECTRICAL SYSTEM Door Lock Control System
WhereEverybodyKnowsYourName

TERMINALS OF ECU
 No. Symbol Terminal Name No. Symbol Terminal Name T8±3 ACT ± Door Lock Motor T8±13 DSWD Door Open Detection Switch 

T8±4
 

ACT +
 

Door Lock Motor
 

T8±14
 

L1
 

Door Key Lock and Unlock Switch
(Lock)
 

T8±5
 

TO
 

Luggage Compartment Door Opener
Motor 

T8±15
 

UL1
 

Door Key Lock and Unlock Switch
(Unlock)
 T8±6 KSW Key Unlock Warning Switch T8±16 E Ground 

T8±7 

LSWP 

Door Unlock Detection Switch 

T8±17 

L2 

Door Lock Control Switch (Lock)
 T8±8 + B2 Actuator Power Source T8±18 UL2 Door Lock Control Switch (Unlock)
 


T8±10 


UL3 


Door Key Lock and Unlock Switch
(Unlock) 


T8±19 


TSW 


Luggage Compartment Door Opener
Switch
 T8±11 LSWD Door Unlock Detection Switch T8±20 + B1 ECU Power Source
 T8±12 DSWP Door Open Detection Switch   
BE±368±
BODY ELECTRICAL SYSTEM Door Lock Control System
WhereEverybodyKnowsYourName

STANDARD VALUE OF ECU TERMINAL
 

Terminals 

Symbols 


Wiring
Color 

Condition 

Standard Value
 T9±3
e T9±4 ACT e ACT+ L±W e L±R Ignition switch OFF 50
or less
 T9±5 e T9±16 T0 e E B e W±B Ignition switch OFF 100
or less
 
T9 6 eT9 16
 
KSW eE
 
Ye WB
 Key unlock warning switch ON.
(Key is inserted into key cylinder). 1
or less
 


T9±6
e T9±16 


KSW
e E 


Y
e W±B 

Key unlock warning switch OFF.
(Key is not inserted into key cylinder). 

1 M

or higher
 

T9±7
e T9±16
 

LSWP
e E
 

P±B
e W±B
 


Door unlock detection switch ON.
(Passenger's) 

1

or less
    Door unlock detection switch OFF. 1 M
higher
 T9±8 e T9±16 +B2 e E L±W e W±B Always 10±14 V
 
T9 10 eT9 16
 
UL3 eE
 
Ge WB
 Door key lock and unlock switch ºunlockº
position. 1
or less
 


T9±10
e T9±16 


UL3
e E 


G
e W±B 

Door key lock and unlock switch OFF or
ºlockº position. 

1 M

or higher
 
T9 11 eT9 16
 
LSWD eE
 
WL eWB
 Door unlock detection switch ON. (driver's) 1
or less
 T9±11 e T9±16 LSWD e E W±L e W±B Door unlock detection switch OFF. (driver's) 1 M
or higher
 

T9 12
eT9 16
 

DSWP
eE
 

RW
eWB
 


Door open detection switch (passenger's)
ON (door opened). 

1

or less
 


T9±12
e T9±16 


DSWP
e E 


R±W
e W±B 


Door open detection switch (passenger's)
OFF (door closed). 


1 M

or higher
 
T9 13 eT9 16
 
DSWD eE
 
RB eWB
 Door open detection switch (driver's)
ON (door opened). 1
or less
 


T9±13
e T9±16 


DSWD
e E 


R±B
e W±B 

Door open detection switch (driver's)
OFF (Door closed). 

1 M

or higher
 

T9 14
eT9 16
 

L1
eE
 

GY
eWB
 


Door key lock and unlock switch ºlockº
position. 

1

or less
 


T9±14
e T9±16 


L1
e E 


G±Y
e W±B 


Door key lock and unlock switch OFF or
ºunlockº position. 


1 M

or higher
 
T9 15 eT9 16
 
UL1 eE
 
GW eWB
 Door key lock and unlock switch ºunlockº
position. 1
or less
 


T9±15
e T9±16 


UL1
e E 


G±W
e W±B 

Door key lock and unlock switch OFF or
ºlockº position. 

1 M

or higher
 


T9±16
e Body
Ground 


E
e Body
Ground 


W±B
e Body
Ground 

Always 

1

or less
    Door lock control switch ªlockº position. 1
or less
 

T9±17 e T9±16 

L2 e E 

R±B e W±B 

Door lock control switch OFF or ªunlockº
position. 

1 M
or higher
    Door lock control switch ªunlockº position 1
or less 

T9±18
e T9±16 

UL2
e E 

G±L
e W±B 

Door lock control switch OFF or ªlockº
position. 

1 M

or higher
±
BODY ELECTRICAL SYSTEM Door Lock Control SystemBE±369
WhereEverybodyKnowsYourName

MATRIX CHART OF PROBLEM SYMPTOMS
Perform troubleshooting of the circuits for the applicable problem symptom in t\
he order given in the chart below.
Proceed to the page located for each circuit.
HINT:
If the instruction ªProceed to next circuit inspection shown on matrix \
chartº is given in the flow chart for each
circuit, proceed to the circuit with the next highest number in the table to con\
tinue the check.

If the trouble still reappears even though there are no abnormalities in a\
ny of the other circuits, then check
or replace the Theft Deterrent and Door Lock ECU as the last step.
See page
BE±376BE±378BE±380BE±382BE±384BE±386BE±388BE±390BE±392IN±32
SymptomSuspect Area
ECU Power Source CircuitActuator Power Source CircuitDoor Lock Motor CircuitLuggage Compartment Door Opener Motor
CircuitDoor Lock Control Switch CircuitDoor key Lock and Unlock Switch CircuitKey Unlock Warning Switch CircuitLuggage Compartment Door Opener Main
Switch and Opener Switch CircuitDoor Open Detection Switch CircuitTheft Deterrent and Door Lock ECU
Whole functions of the door lock control system does notWhole functions of the door lock control system does not
t12435operate.12435
All doors or some doors are not locked and unlocked with theAll doors or some doors are not locked and unlocked with the
Door Lock Control Switch and Key o
perated SwitchDoor Lock Control Switch and Key operated Switch.
(Luggage compartment door opener function normally oper3124(Luggage compartment door opener function normally oper-
t)
3124
ate.)
Doors cannot be locked or unlocked with the door lock con-Doors cannot be locked or unlocked with the door lock con
trol switch. (Doors lock and unlock normally with the key op-1234(yy
erated switch.)
1234
Doors are not locked or unlocked with the key operatedDoors are not locked or unlocked with the key o erated
switch. (Doors lock and unlock normally with the door lock12(y
control switch.)
12
Key confinementprevention function does not operateKey confinement prevention function does not operate.123y
Doors lock and unlock normally with the key o
perated switch123Doors lock and unlock normally with the key operated switch.
Luggage compartment door opener function does not oper-Luggage compartment door opener function does not oper-
t213ate.213
±
BODY ELECTRICAL SYSTEM Door Lock Control SystemBE±371
WhereEverybodyKnowsYourName

Door Key Lock and Unlock Switch Circuit
CIRCUIT DESCRIPTION
The door key lock and unlock switch is built in the door key cylinder.
When the key is turned to the lock side, terminal 3 of the switch is grounde\
d and when the key is turned
to the unlock side, terminal 1 of the switch is grounded.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
OKOK NG NG
Check door key lock and unlock switch.
Check harness and connectors between ECU
and switch, switch and body ground
(See page IN±27). Replace door key lock and unlock
switch.
1
2
Proceed to next circuit inspection shown on
matrix chart (See page
BE±371). Repair or replace harness or
connector.
WIRING DIAGRAM
BE±386±
BODY ELECTRICAL SYSTEM Door Lock Control System
WhereEverybodyKnowsYourName