1991 LEXUS SC400 sensor

(b) Remove four clips.
(c) Remove the clip and ambient temperature sensor.
(d) Remove four nuts.
(e) Remove ten clips.
(f) Remove two bolts.
(g) Disconnect the connectors.
(h) Remove the bumper cover assy.
6. REMOVE REINFORCEMENT Remove six bolts and the reinforcement.
7. REMOVE UPPER REINFORCEMENT Remove eight bolts and the reinforcement.
8. REMOVE HEADLIGHT (High Beam)
(a) Remove two screws, a clip and the headlight.
(b) Disconnect the connector.
±
BODY Bumper (Front Bumper)BO±13
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POWER MIRROR CONTROL
SYSTEM
Description
The Power Miror Control System carries out mirror left/right and up/down ad\
justments electrically when the Mir-
ror Switch is operated. In addition, operation of the Driving Position M\
emory and Return Switches makes it pos-
sible to store the adjusted position in memory and reproduce each adjustment \
when desired. The component
parts of this system and their functions are described in the following table\
.
Parts NameFunction
Outside Rear View
Mirror ECUThe Outside Rear View Mirror ECU is supplied with power from the DOME and RADIO
NO.2 fuses and is connected to the Tilt and Telescopic ECU, Mirror Switch, each
mirror motor and ground.
Rear View Adjustment
SwitchOperation of this switch sends left/right, up/down signals to Outside Re\
ar View Mirror
ECU.
Driving Position Memory
and Return SwitchesMemory and return signals are sent to the ECU via the Tilt and Telescopic ECU.
Mirror MotorThese motors operate on current from the Outside Rear View Mirror ECU, moving
the various parts of the mirror directly.
These sensors send signals about the motor positions to the ECU for stor\
ing in memory
and during return operation.
Left/Right Select SwitchThis switch is used to select operation of the Rear View Adjustment Switch for the
leftor right hand side mirror.
±
BODY ELECTRICAL SYSTEM Power Mirror Control SystemBE±183
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2. INSPECT MIRROR POSITION SENSORSHINT: Strip off the vinyl tape of the connector and remove ter-
minals 1, 2, 3, 5 and 9 from the connector housing.
(a) Connect a series of three 1.5 volt dry cell batteries.
(b) Connect the positive (+) lead from the dry cell batteriesto terminal 5 and the negative (±) lead to terminal 9.
(c) Connect the positive (+) lead from the voltmeter to
terminal 6 and the negative (±) lead to terminal 9.
(d) Apply battery voltage to terminals 2 and 3, check that the voltage gradually changes according to the table
below while the mirror moves between the uppermost
position and lowermost position.
Mirror
positionLowermostUppermost
Voltage2.8 ± 5.0Changes
gradually0 ± 0.9
If voltage value is not as specified, replace the motor assem-
bly.
(e) Disconnect the four leads of the battery and voltmeter.
(f) Connect the positive (+) lead from the voltmeter to terminal 4 and the negative (±) lead to terminal 9.
(g) Apply battery voltage to terminals 1 and 2n inspect that the voltage gradually changes according to the table
below while the mirror moves between the leftmost
position and rightmost position.
Mirror
PositionLeftmostRightmost
Voltage
Left
Mirror2.8 ± 5.0Changes
gradually0 ± 0.9
VoltageRight
Mirror0 ± 0.9Changes
gradually2.8 ± 5.0
If voltage value is not as specified, replace the motor assem-
bly.
(Mirror ECU)
REMOVAL AND INSTALLATION OF
MIRROR ECU
REMOVAL AND INSTALL MIRROR ECU (a) Remove the No. 1 under cover .(See page BO±112)
(b) Re mo ve th e two scre ws an d disc onnect the two
connectors and then pull out the ECU.
(c) For installation, follow the removal procedure in reverse.
±
BODY ELECTRICAL SYSTEM Power Mirror Control SystemBE±187
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Troubleshooting
You will find the cause of trouble more easily by properly using the table \
shown below. In this table, the
numbers indicate the order of priority of the causes of trouble. Check each part in \
the order shown. If neces-
sary, replace the part.
See pageBE±4 ,20BE±4,21BE±186BE±186 ±±BE±188SR±60 ±±IN±32BE±187
TroubleParts
name
RADIO NO. 2 FuseDOME FuseMirror SwitchMirror MotorWire HarnessMirror ECUDriving Position SwitchDriving Position Switch
(Position is not set)Tilt and Telescopic ECUMirror Sensors
Mirror does not operate.112354
Mirror operates abnormally1243
Mirror does not return to the memorized position.
(w/ Memory System)642135
Mirror returns to a position which is not memorized.
(w/ Memory System)312
BE±190±
BODY ELECTRICAL SYSTEM Power Mirror Control System
WhereEverybodyKnowsYourName

DESCRIPTION
The Power Seat Control System carries out seat slide, front vertical, rear \
vertical, reclining and lumbar support
position adjustments electrically. Power seat switch and lumbar support switch.
In addition, operation of the memory switch makes it possible to store the positions of the slide, front vertical,
rear vertical and reclining adjustments in memory and return to the posi\
tion.
The component parts of this system and their function are described in t\
he following table.
 Parts Name\
 \
Function
 








Driver's Seat ECU
\
 
\


\


\


\

\

The seat ECU controls power operation, memory operation, and position re\
turn
operation of the power seat. When input is received from the power seat \
switch,
the relay inside the ECU is controlled and the power seat operates. The \
seat
memory and position return are controlled by mutual communication betwee\
n the
electrically operated Tilt and Telescopic ECU and the seat ECU.
 

Power Seat Switch\
 
\

\

Operation of this switch sends slide, front vertical, rear vertical, rec\
lining signals
to ECU.
 




Driving Position
Memory and Return
Switch\
 
\


\

\

Memory and Return Signals are sent to the seat ECU via the Tilt and Telescopic
ECU.
 






Lumbar Support
Switch
\
 
\


\


\

\

This switch is supplied with power from the DOOR fuse. When the switch i\
s
operated, power is supplied to the lumbar support motor controlling the \
direction
in which the motor turns and turning the current ON and OFF. This switch is not
connected to the ECU and the adjustment position cannot be stored in mem\
ory
for return operation.
 

Position Sensor
\
 
\

\
This sensor sends signals on the position of each motor (slide, front v\
ertical, rear
vertical and reclining) to the ECU for use in memory and return.
 

*Motor
\
 
\

\

These motors operate on current from the driver's seat ECU moving the various
parts of the seat directly. Each motor has a built±in circuit breaker.
*: Slide, Front Vertical, Rear Vertical, Lumbar Support and Reclining.
Motors contained in each seat are described in the following table.
 Motor Slide Front
Vertical
 Rear
Vertical
 Reclining Lumbar
Support 

Seat 

Motor 


Vertical
Motor
 


Vertical
Motor
 


g
Motor 


Support
Motor
 Driver's Seat O* O* O* O* O
*: Operated by the memory and return functions. BE±266
±
BODY ELECTRICAL SYSTEM Power Seat Control System (Driver's Seat)
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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)
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WIRING DIAGRAM
No.SymbolTerminal NameNo.SymbolTerminal NameNo.SymbolTerminal Name
P11
±1SLDFSlide Switch (Forward)P11±13CHKCheckP10±7IGIgnition Switch
2RCLFReclining Switch (Forward)14SSRRReclining Sensor8GND2Ground 2
3FUPFront Vertical Switch (UP)15SSRVRear Vertical Sensor9SLD±Slide Motor (Back)
4RUPRear Vertical Switch (UP)16SSRSSlide Sensor10RCL±Reclining Motor (Down)
5SSFVFront Vertical Switch17SOSerial Communications11FRV±Front Vertical Motor (Down)
6PVCCPosition Sensor Power
Source18SGNDSensor Ground12RRV±Rear Vertical Motor (Down)
7SYSBPower SourceP10±1GNDGround13RRV+Rear Vertical Motor (For-
ward)
8SISerial Communications2SLD+Slide Motor (Forward)14+B2Power Source
9SLDRSlide Switch (Back)3RCL+Reclining Motor (Up)15PNeutral Start Switch
10RCLRReclining Switch (Back)4FRV+Front Vertical Motor (Up)16±±±±
11FDWNFront Vertical Switch (Down)5+BPower Source
12RDWNRear Vertical Switch (Down)6STOPStop Light
BE±272±
BODY ELECTRICAL SYSTEM Power Seat Control System (Driver's Seat)
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WIRING DIAGRAM
ECU Power Source Circuit
CIRCUIT DESCRIPTION
This circuit provides power for ECU operation and is also the power source f\
or the sensors.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
Check DOME fuse.NGCheck for short in all the harness
and components connected to
DOME fuse.
(See attached wiring diagram).
OK
Check voltage between terminals SYSB
and SGND of ECU connector. Proceed to next circuit inspection
shown on matrix chart
(See page
BE±276).
Check continuity between terminal SGND
of ECU connector and body ground. OK
NG
OK NG
Replace or repair harness or
connector.
Check and repair harness or connector
between ECU and battery.
BE±286±
BODY ELECTRICAL SYSTEM Power Seat Control System (Driver's Seat)
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