1991 LEXUS SC300 mirror

Troubleshooting
You will find the cause of trouble more easily by properly using the tabl\
e shown below. In this table, the numbers
indicate the order or priority of the causes of trouble. Check each part\
in the order shown. If necessary, replace
the part.
See page
BE ± 4, 20BE ± 192BE ± 192
±
Trouble
Part Name
DOOR FuseFuel Lid Opener Switch
Mirror SwitchFuel Lid Opener SolenoidWire Harness
Fuel lid opener system does not operate1234
±
BODY ELECTRICAL SYSTEM Fuel Lid Opener SystemBE±193
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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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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)
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WIRING DIAGRAM
Check harness and connector between
ECU and tilt & telescopic ECU (See page
IN±27). NG
NG
OK
OK
Check return operation of tilt and
telescopic ECU, and mirror ECU. Repair or replace harness or
connector.
Check and replace tilt &
telescopic ECU.
Proceed to next circuit inspection shown on
matrix chart (See page BE±276).
Serial Communication Circuit
CIRCUIT DESCRIPTION
Memory and return command signals and mutual commu-
nication during return operation pass between the ECU and
the tilt & telescopic ECU in the from of serial data communica-
tion. Signals activating memory and return operation are sent
from the tilt & telescopic ECU to the ECU and mirror ECU.
When the ECU receives a memory signals, its position is
memorized, and when a return signal is received, the position
is returned to the memorized position.
During return operation, tilt & telescopic ECU and ECU continue mutual communi\
cation constantly, and if a mal-
function should occur in the communication wire, the tilt & telescopic ECU stops signal output to the ECU and
stops return operation. However, the tilt & telescopic ECU continues return operation. Even with power \
return
stopped, manual switch operation of the power seat is possible. The mirror ECU receives activation signals only
and is not involved in reciprocal communication during return operation, so\
even when a reply signal from the
ECU to the tilt & telescopic ECU is abnormal and the power seat stops retur\
n operation, the mirror ECU contin-
ues return operation.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
BE±306±
BODY ELECTRICAL SYSTEM Power Seat Control System (Driver's Seat)
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OKNG
OKNG
INSPECTION PROCEDURE
1Check for open and short in harness and connector between ECU and tilt & telescopi\
c ECU (See
page IN±27 ).
HintDepending on the differences that exist for return opera-
tion or non±return operation of each system, the prob-
lems is the harness and connector shown in the table
below may be considered.
Trouble areaTilt &
TelescopicMirrorSeat
Open
Short
Open
Open or Short
Repair or replace harness or connector.
2Check return operation by tilt & telescopic ECU, and mirror ECU.
Check that return operation is normal for tilt, telescopic and mirror fu\
nctions.C
Check and replace tilt & Telescopic ECU.
Proceed to next circuit inspection shown on
matrix chart (See page BE±276).
±
BODY ELECTRICAL SYSTEM Power Seat Control System (Driver's Seat)BE±307
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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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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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No.Part NameRelated Systems or Parts
22MAIN
Upstream of ALT±S and EFI Fuse
23AM2
Charging System
Engine23AM2
AIR±BAG System
24ABS NO. 2
ABS and TRAC
25INJ
Charging System
Engine25INJ
AIR±BAG System
26DEF
Defogger System

Power Seat System
Sliding Roof System

A/C System
Liquid Crystal Inner Mirror System
27DOME
Combination Meter System
Interior Light System27DOME
ABS and TRAC
Wireless Door Lock Control System

Cruise Control System
Auto±Tilt away Steering

Theft Deterrent System
28EFI
Engine
29HAZ HORN
Turn Signal and Hazard Warning Light System29HAZ±HORN
Horn System
30RADIO NO. 1
Audio System
31TEL
TEL System
32ALT±S
Charging System
33TRAC
ABS and TRAC
34HEAD (RH±LWR)
Headlight System
35HEAD (LH±LWR)
Headlight System
36HEAD (RH±UPR)
Headlight System
37HEAD (LH±UPR)
Headlight System
38HTR
Blow Motor
±
BODY ELECTRICAL SYSTEM Power SourceBE±19
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