ignition LEXUS SC300 1991 Service Repair Manual

STARTER RELAY
INSPECTION OF STARTER RELAY
1. DISCONNECT CABLE FROM NEGATIVE TERMINAL OFBATTERY
CAUTION: Work must be started after approx. 20 seconds or
longer from the time the ignition switch is turned to the
ºLOCKº position and the negative (±) terminal cable is dis-
connected from the battery.
2. REMOVE STATER RELAY LOCATION: In the engine compartment relay box.
3. INSPECT STARTER RELAY
A. Inspect relay continuity
(a) Using an ohmmeter, check that there is continuitybetween terminals 1 and 2.
(b) Check that there is no continuity between terminals 3 and 5.
If continuity is not as specified, replace the relay.
B. Inspect relay operation (a) Apply battery voltage across terminals 1 and 2.
(b) Using an ohmmeter, check that there is continuitybetween terminals 3 and 5.
If operation is not as specified, replace the relay.
4. REINSTALL STARTER RELAY
5. RECONNECT CABLE TO NEGATIVE TERMINAL OF BATTERY
NEUTRAL START SWITCH
(See AT section)
THEFT DETERRENT SYSTEM
(See BE section)
±
STARTING SYSTEM Starter Relay, Neutral Start Switch, Theft Deterrent
SystemST±35
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SR±52).
WIRING DIAGRAM
Ignition Switch Circuit
CIRCUIT DESCRIPTION
The ON, OFF signal from the IG switch is sent to the ECU.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
SR±92±
STEERING STEERING COLUMN
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NGOK
OKNG
INSPECTION PROCEDURE
1Check voltage between terminal IG of ECU connector and body ground.
C
OK
PRemove ECU with connectors still connected.
Measure voltage between terminal EG of ECU connec-
tor and body ground when ignition switch is on and off.
Proceed to next circuit inspection shown on matrix chart
(See page SR±52.)
2Check ECU±IG fuse.
C
OK
PRemove ECU±IG fuse from J/B No. 1.
Check continuity of ECU±IG fuse.
Continuity
Check for short in all the harness and components con-
nected to ECU±IG fuse.
Check and repair harness or connector between
ECU and battery.
±
STEERING STEERING COLUMNSR±93
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OKNG
NGOK
INSPECTION PROCEDURE
1Check shift position indicator.
Check that ªPº lights up on the shift indicator when P position is shif\
ted into, and that ªPº is extin-
guished when shifting into another position.P
Check and repair shift position indicator circuit (See
page BE±168 ).
2Check voltage between terminal P of ECU connector and body ground.
C
OK
PRemove ECU with connectors still connected.
1. Turn ignition switch on.
2. Measure voltage between terminal P of ECU con-
nector and body ground when the shift lever is oper-
ated.
Proceed to next circuit inspection shown on matrix chart
(See page SR±52).
Check for open in harness and connectors be-
tween ECU and [IK1] connector.
±
STEERING STEERING COLUMNSR±95
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OKNG
NGOK
NGOK
OKNG
INSPECTION PROCEDURE
1Check operation of brake warning light.
Check that the brake warning light in the instrument panel comes on when the \
parking brake is opera-
tion with the engine running, and the light goes off when the parking brake is not operating.C
Check brake warning light circuit.
2Input signal check.
C
OK
1. See input signal check.
2. Check the indicator light when the parking brake isoperating.
The indicator light goes off when the parking brake
is operating.
Proceed to next circuit inspection shown on matrix
chart.
3Check voltage between terminal PKB of tilt & telescopic ECU connector and bod\
y ground.
C
OK
PRemove tilt & telescopic ECU with connectors still con-
nected.
1. Turn ignition switch ON.
2. Measure voltage between terminal PKB of tilt & telescopic ECU connector and body ground, when
the parking brake lever is operating.
Proceed to next circuit inspection shown on matrix
chart.
4Check for open in harness and connector between tilt & telescopic ECU and brak\
e warning light
(See page IN±33).
.
Repair or replace harness or connector
Check and replace tilt & telescopic ECU.
±
STEERING STEERING COLUMNSR±97
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SR±52).
IN±33 ).
Unlock Warning Switch Circuit
CIRCUIT DESCRIPTION
Whether or not the key is inserted in the key cylinder is detected and a signal\
is sent to the ECU.
(The switch is ON (closed) when the ignition key is inserted.)
 Ignition key Unlock Warning Switch UWSW Voltage
 

Out 

Opened 

10±14 V
 In Closed Below 1 V
DIAGNOSTIC CHARTDIAGNOSTIC CHART
SR±100±
STEERING STEERING COLUMN
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NGOK
OKNG
OKNG
INSPECTION PROCEDURE
1Check voltage between terminal UWSW of ECU connector and body ground
C
OK
PRemove ECU with connectors still connected.
Measure voltage between terminal UWSW of ECU con-
nector and body ground with the ignition key inserted,
or removed.
Proceed to next circuit inspection shown on matrix chart
(See page SR±52).
2Check unlock warning switch.
C
OK
PDisconnect unlock warning switch connector.
Measure resistance between terminals 9 and 10 of un-
lock warning switch connector with the ignition key in-
serted or removed.
Replace unlock warning switch.
3Check harness and connector between ECU and unlock warning switch (See \
page IN±33).
Repair or replace harness or connector.
Check and replace ECU.
±
STEERING STEERING COLUMNSR±101
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MAIN POINTS OF REMOVAL AND
INSTALLATION
NOTICE:
wIf the SRS (Supplemental Restraint System) connector is
disconnected with the ignition switch at ON or ACC,
diagnostic trouble codes will be recorded.
w Never use SRS parts from another vehicle. When
replacing parts, replace with new parts.
1. DISCONNECT NEGATIVE (±) TERMINAL CABLE FROM
BATTERY
CAUTION: W ork must be started after 90 seconds from the time
the ignition switch is turned to the ªLOCKº position and the
negative (±) terminal cable is disconnected from the battery.
(See RS section)
2. REMOVE STEERING WHEEL PAD
(a) Place the front wheels facing straight ahead.
(b) Remove the No.2 and No.3 covers.
(c) Using a torx wrench, loosen the 4 torx screws. Torx wrench: T30 (Part No. 09042±00010 or locally manufac-
tured tool)
HINT: Loosen the 4 screws until the groove along the screw
circumference catches on the screw case.
(d) P u l l t h e w heel pad out from the steering wheel and
disconnect the Airbag connector.
NOTICE: When removing the wheel pad, take care not to pull
the Airbag wire harness.
CAUTION:
w When storing the wheel pad, keep the upper surface of
the pad facing upward.
w Never disassemble the wheel pad.
3. REMOVE STEERING WHEEL
(a) Disconnect the connector.
(b) Remove the steering wheel set nut.
(c) Place matchmarks on the steering wheel and main shaft.
(d) Using SST, remove the wheel.
SC400:
SST 09213±31021
SC300:
SST 09609±20011
SR±10
±
STEERING STEERING COLUMN
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STEERING COLUMN DISASSEMBLY
SR0ER±03
NOTICE: When placing the breakaway bracket in a vise
during disassembly or assembly of the steering column,
use aluminum, etc. to prevent scratches to the tip of the
capsule.
1. REMOVE IGNITION KEY CYLINDER ILLUMINATION
2. REMOVE SLIDING YOKE Place matchmarks on the sliding yoke and main shaft.
3. REMOVE LOWER DUST COVER
(a) Remove the clip and dust cover.
(b) Using a screwdriver, remove the dust seal.
4. REMOVE COLUMN UPPER BRACKET
(a) U s i n g a c e n t e r i n g p u n c h , m a r k t h e c e n t e r o f t h e 2 tapered±head bolts.
(b) U s i n g a 4 ± 5 m m ( 0 . 16±0.20 in.) drill, drill into the 2
tapered±head bolts.
(c) Using a screw extractor, remove the 2 tapered±head bolts.
(d) Remove the bracket and column upper clamp.
SR±14
±
STEERING STEERING COLUMN
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(b) Remove the main shaft from the column tube.
(c) Remove the spring, thrust collar and bearing.
STEERING COLUMN INSPECTION AND
REPLACEMENT
SR0ES±03
1. INSPECT KEY CYLINDERCheck that the steering lock mechanism operates properly.
2. IF NECESSARY, REPLACE KEY CYLINDER
(a) Place the ignition key at the ACC position.
(b) Push down the stop pin with a thin rod, and pull out the key cylinder.
(c) Install a new key cylinder. HINT: Make sure the ignition key is at the ACC position.
3. INSPECT UPPER BEARING Check the upper bearing rotation condition and check for ab-
normal noise.
If the bearing is worn or damaged, replace the column upper
tube.
STEERING COLUMN ASSEMBLY
SR0ET±04
1. APPLY MOLYBDENUM DISULPHIDE LITHIUM BASEGREASE (See page SR±12)
2. INSTALL MAIN SHAFT
(a) Install the bearing, thrust collar and spring to the main shaft.
(b) Install the main shaft into the upper column tube.
±
STEERING STEERING COLUMNSR±19
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