ect LEXUS SC300 1991 Service Repair Manual

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
WhereEverybodyKnowsYourName

INSPECTION OF MIRROR ECU
1. INSPECT MIRROR ECU CIRCUITDisconnect the connectors from the ECU and inspect the
connector on the wire harness side as shown in the chart be-
low.
Check forTester connectionConditionSpecified value
ContinuityA1±A2ConstantContinuity
A1±A3ConstantContinuity
A8±A10ConstantContinuity
A9±A10ConstantContinuity
A11±GroundConstantContinuity
A12±A13ConstantContinuity
A16±*ConstantContinuity
B1±B2Right mirror switch on DOWNContinuity
B1±B4Right mirror switch to RIGHTContinuity
B1±B5Left mirror switch to RIGHTContinuity
B1±B6Left mirror switch to DOWNContinuity
B2±B3Right mirror switch to UPContinuity
B3±B4Right mirror switch to LEFTContinuity
B3±B5Left mirror switch to LEFTContinuity
B3±B6Left mirror switch to UPContinuity
VoltageA4±GroundConstantBattery positive voltage
A7±GroundIgnition switch to ACCBattery positive voltageA7±GroundIgnition switch to OFFNo voltage
*: Terminal 1/18 of the Tilt and Telescopic ECU
If circuit is not as specified, inspect the wire harness and mir-
ror switch or motor assembly.
BE±188
±
BODY ELECTRICAL SYSTEM Power Mirror Control System
WhereEverybodyKnowsYourName

2. INSPECT MIRROR ECU OPERATIONConnect the connectors and using a voltmeter with high im-
pedance (10 k
/V minimum), measure the voltage at each
terminal and body ground.
Check forTester connectionConditionSpecified value
VoltageA1±GroundRight mirror switch to LEFTBattery positive voltage
A2±GroundRight mirror switch to UPBattery positive voltage
A3±GroundRight mirror switch to RIGHT or DOWNBattery positive voltage
*A5±GroundRight mirror to leftmost position0±0.9 V*A5±GroundRight mirror to rightmost position2.8±5.0 V
*A6±GroundRight mirror to lowermost position2.8±5.0 V*A6±GroundRight mirror to uppermost position0±0.9 V
A8±GroundLeft mirror switch to RIGHTBattery positive voltage
A9±GroundLeft mirror switch to UPBattery positive voltage
A10±GroundLeft mirror switch to LEFT or DOWNBattery positive voltage
A13±GroundRight or left mirror switch to any position except
OFFApprox. 5 V
*A14±GroundLeft mirror to leftmost position2.8±5.0 V*A14±GroundLeft mirror to rightmost position0±0.9 V
*A15±GroundLeft mirror to lowermost position2.8±5.0 V*A15±GroundLeft mirror to uppermost position0±0.9 V
B2±GroundConstantApprox. 5 V
B4±GroundConstantApprox. 5 V
B5±GroundConstantApprox. 5 V
B6±GroundConstantApprox. 5 V
*: Confirm that the voltage changes gradually while the mirror moves
If operation is not as specified, inspect the wire harness and
mirror switch or motor assembly. Then if these are correct, re-
place the ECU.
±
BODY ELECTRICAL SYSTEM Power Mirror Control SystemBE±189
WhereEverybodyKnowsYourName

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

FUEL LID OPENER SYSTEM
Parts Location
Wiring and Connector Diagrams
±
BODY ELECTRICAL SYSTEM Fuel Lid Opener SystemBE±191
WhereEverybodyKnowsYourName

Parts Inspection
(Fuel Lid Opener Switch)
REMOVAL AND INSTALLATION OF FUEL
LID OPENER SWITCH
REMOVE AND INSTALL FUEL LID OPENER SWITCH(a) Remove No. 1 lower finish panel.
(See Instrument Panel on page BO±113)
(b) Remove the key cylinder, then remove the fuel lid opener
switch assembly from the pad.
(c) Install the opener switch assembly and key cylinder to
the pad.
(d) Install the No. 1 lower finish panel. (See Instrument Panel on page BO±116)
INSPECTION OF FUEL LID OPENER
SWITCH
INSPECT SWITCH CONTINUITY
(a) Check that there is continuity between terminals with the
switch ON (Lever pulled).
(b) Check that there is no continuity between terminals with
the switch OFF (Lever free).
If continuity is not as specified, replace the switch assembly.
(Fuel Lid Opener Solenoid)
REMOVAL AND INSTALLATION OF FUEL
LID OPENER SOLENOID
REMOVE AND INSTALL FUEL LID SOLENOID (a) Disconnect the connector from the solenoid.
(b) Open the fuel lid and remove the solenoid lock nut, thenremove the solenoid.
(c) Install the solenoid in place with the lock nut.
(d) Connect the connector to the solenoid.
INSPECTION OF FUEL LID OPENER
SOLENOID
INSPECT SOLENOID OPERATION (a) Apply battery voltage to the terminals.
(b) Check that the solenoid operates in the open direction.
If operation is not as specified, replace the solenoid.
BE±192
±
BODY ELECTRICAL SYSTEM Fuel Lid Opener System
WhereEverybodyKnowsYourName

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
WhereEverybodyKnowsYourName

CLOCK
Troubleshooting
HINT: Troubleshoot the clock according to the table below.
Clock will not operate1
Clock loses or gains time2
1CLOCK WILL NOT OPERATE
(a) Check that the battery voltage is 10±16 V.
If voltage is not as specified, replace the battery.
(b) Check that the DOME fuse is not blown.
If the fuse is blown, replace the fuse and check for short.
(c) Troubleshoot the clock as follows.
HINT: Inspect the connector on the wire harness side.
BE±194
±
BODY ELECTRICAL SYSTEM Clock
Is there battery voltage between terminal
+B and body ground?
Is there continuity between terminal GND
and body ground?
Replace clock. Open or
short circuit in wire harness between
terminal +B and DOME fuse.
Open circuit in wire harness between
terminal GND and body ground.
WhereEverybodyKnowsYourName

2CLOCK LOSES OR GAINS TIME
(a) Check that the battery voltage is 10±16 V.
If voltage is not as specified, replace the battery.
(b) Inspect the error of the clock.
Allowable error (par day): + 2.0 seconds
If the error exceeds the allowable error, replace the clock.
(c) Check if the clock adjusting button is sticking in position
and has failed to return.
If the button has not returned, repair or replace the clock.
(d) troubleshoot the clock as follows.
HINT: Inspect the connector on the wire harness side.
±
BODY ELECTRICAL SYSTEM ClockBE±195
Is there 10 ± 16 V between terminal +B and
body ground?
Adjust or replace clock. Locate cause, and repair or recharge
battery.
Below 10 V
WhereEverybodyKnowsYourName

AUDIO SYSTEM
System Description
RADIO WAVE BAND
The radio wave bands used in radio broadcasting are as follows:
Frequency 30 kHz300 kHz 3 MHz30 MHz300 MHz
DesignationLFMFHFVHF
Radio waveAM
eFM
e
Modulation methodAmplitude modulationFrequency modulation
LF: Low Frequency MF: Medium Frequency HF: High Frequency VH\
F: Very High Frequency
SERVICE AREA
There are great differences in the size of the service area for
AM, FM monaural, and FM stereo broadcasting. Thus it may
happen that FM broadcasts cannot be received even though
AM comes in very clearly.
Not only does FM stereo have the smallest service area, but
it also picks up static and other types of interference (ºnoiseº)
easily.
RECEPTION PROBLEMS
Besides the problem of static, there are also the problems
called ºfadingº, ºmultipathº and ºfade outº. These pro\
blems
are caused not by electrical noise but by the nature of the ra-
dio waves themselves.
Fading
Besides electrical interference, AM broadcasts are also sus-
ceptible to other types of interference, especially at night.
This is because AM radio waves bounce off the ionosphere
at night. These radio waves then interfere with the signals
from the same transmitter that reach the vehicle's antenna di-
rectly. This type of interference is called ºfadingº.
Multipath
One type of interference caused by the bouncing of radio
waves off of obstructions is called ºmultipathº. Multipath oc-
curs when a signal from the broadcast transmitter antenna
bounces off of buildings and mountains and interferes with
the signal that is received directly.
Fade Out
Because FM radio waves are of higher frequencies than AM
radio waves, they bounce off of buildings, mountains, and
other obstructions. For this reason, FM si gnals often seem to
gradually disappear or fade away as the vehicle goes behind
a building or other obstruction. This is called ºfade outº.
BE±196
±
BODY ELECTRICAL SYSTEM Audio System
WhereEverybodyKnowsYourName