LEXUS SC400 1991 Service Repair Manual

INSPECTION OF IGNITION COIL
1. (RH IGNITION COIL)REMOVE IGNITION COIL (See page IG±21)
2. (LH IGNITION COIL)
DISCONNECT IGNITION COIL CONNECTOR AND HIGH±
TENSION CORD FROM IGNITION COIL
3. INSPECT PRIMARY COIL RESISTANCE Using an ohmmeter, measure the resistance between posi-
tive (+) and negative (±) terminals.
Primary coil resistance (Cold): 0.40±0.50

If the resistance is not as specified, replace the ignition coil.
4. INSPECT SECONDARY COIL RESISTANCE Using an ohmmeter, measure the resistance between posi-
tive (+) and high±tension terminals.
Secondary coil resistance (Cold): 10.0±14.0 k

If the resistance is not as specified, replace the ignition coil.
5. (RH IGNITION COIL) REINSTALL IGNITION COIL (See page IG±22)
6. (LH IGNITION COIL) RECONNECT IGNITION COIL CONNECTOR AND HIGH±
TENSION CORD FROM IGNITION COIL
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IGNITION SYSTEM On±Vehicle InspectionIG±9
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INSPECTION OF CAM POSITION
SENSORS
1. DISCONNECT CAM POSITION SENSOR CONNECTORS(a) (RH Cam Position Sensor)Disconnect the cam position sensor connector from the
ignition coil bracket.
(See steps 5 (a) on page IG±24)
(b) Disconnect the cam position sensor connectors.
2. INSPECT CAM POSITION SENSOR RESISTANCE Using an ohmmeter, measure the resistance between termi-
nals.
Resistance (Cold):
835±1,350
at ±10± +40 5C (14±104 5F)
If the resistance is not as specified, replace the cam position
sensor.
3. RECONNECT CAM POSITION SENSOR CONNECTORS
INSPECTION OF ENGINE SPEED
SENSOR
1. REMOVE ENGINE SPEED SENSOR (See page IG±30)
2. INSPECT ENGINE SPEED SENSOR RESISTANCE Using an ohmmeter, measure the resistance between termi-
nals.
Resistance (Cold):
835±1,350
at ±10± +40 5C (14±104 5F)
If the resistance is not as specified, replace the engine speed
sensor.
3. REINSTALL ENGINE SPEED SENSOR (See page IG±30)
INSPECTION OF ENGINE SPEED
SENSOR
(See procedure Spark Test on page IG±6)
IG±10
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IGNITION SYSTEM On±Vehicle Inspection
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HIGH±TENSION CORDS AND CORD
CLAMPS
COMPONENTS FOR REMOVAL AND
INSTALLATION
REMOVAL OF HIGH±TENSION CORDS
1. DISCONNECT CABLE FROM NEGATIVE TERMINAL OFBATTERY
CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ºLOCKº position and the negative (±) termi-
nal cable is disconnected from the battery.
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IGNITION SYSTEM High±Tension Cords and Cord ClampsIG±11
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2. REMOVE INTAKE AIR CONNECTOR(a) Disconnect the following hoses:(1) Air hose from ISC valve
(2) Air hose (from PS air control valve) from intake air connector
(b) Remove the bolt holding the intake air connector to the cylinder head cover.
(c) Loosen the two hose clamps.
(d) Disconnect the intake air connector from the throttle
body and air cleaner hose, and remove the throttle body.
3. REMOVE UPPER HIGH±TENSION CORD COVER (a) Remove the two mounting bolts.
(b) Disconnect the front side claw groove of the cord coverfrom the claw of the lower cover, and remove the cord
cover.
4. REMOVE RH ENGINE WIRE COVER Remove the bolt and engine wire cover.
5. REMOVE LH ENGINE WIRE COVER Remove the two bolts and engine wire cover.
IG±12
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IGNITION SYSTEM High±Tension Cords and Cord Clamps
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6. REMOVE VSV FOR EVAP SYSTEMRemove the two bolts, and disconnect the VSV from cylinder
head and timing belt cover.
7. REMOVE RH NO.3 TIMING BELT COVER Remove the three bolts and timing belt cover.
8. REMOVE LH NO.3 TIMING BELT COVER (a) Remove the four mounting bolts.
(b) Disconnect the cord grommet from the timing belt cover,
and remove the timing belt cover.
(c) Remove the cord grommet from the high±tension cord.
9. REMOVE HIGH±TENSION CORDS (a) Disconnect the high±tension cords from the spark plugs
and distributor caps. Disconnect the high±tension cords
at the rubber boot. Do not pull on the cords.
NOTICE: Pulling on or bending the cords may damage
the conductor inside.
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IGNITION SYSTEM High±Tension Cords and Cord ClampsIG±13
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(b) Disconnect the high±tension cords from the ignitioncoils.
w Using a screwdriver, lift up the lock claw and
disconnect the holder from the ignition coil.
w Disconnect the high±tension cord at the grommet.
Do not pull on the cord.
NOTICE: Pulling on or bending the cords may damage
the conductor inside.
(c) Disc onnect the high±tension cords from the cord
clamps and lower high±tension cord cover, and remove
the ten high±tension cords.
(d) Remove the five cords clamp from the high±tension cords.
10. REMOVE RH HIGH±TENSION CORD CLAMPS (a) Re mo ve th e two bo lts an d two hi gh±tension cord
clamps.
(b) Remove the cord clamp from the front high±tension cord clamp.
11. REMOVE LH HIGH±TENSION CORD CLAMPS (a) Re mo ve th e two bo lts an d two hi gh±tension cord
clamps.
(b) Remove the cord clamp from the front high±tension cord clamp.
12. REMOVE LOWER HIGH±TENSION CORD COVER Remove the bolt and high±tension cord cover.
IG±14
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IGNITION SYSTEM High±Tension Cords and Cord Clamps
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INSTALLATION OF HIGH±TENSION
CORDS AND CORD CLAMPS
(See Components on page IG±11)
1. INSTALL LOWER HIGH±TENSION CORD COVER Install the high±tension cord cover with the bolt.
2. INSTALL RH HIGH±TENSION CORD CLAMPS (a) Install the cord clamp to the front high±tension cordclamp.
(b) Install front and rear high±tension cord clamps with the two bolts.
HINT: Place the front and rear ends of the front high±tension
cord clamp on the rear high±tension cord clamp and lower
high±tension cord cover.
3. INSTALL LH HIGH±TENSION CORD CLAMPS (a) Install the cord clamp to the front high±tension cordclamp.
(b) Install front and rear high±tension cord clamps with the two bolts.
HINT: Place the front and rear ends of the front high±tension
cord clamp on the rear high±tension cord clamp and lower
high±tension cord cover.
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IGNITION SYSTEM High±Tension Cords and Cord ClampsIG±15
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4. INSTALL HIGH±TENSION CORDS(a) Connect the high±tension cords to the spark plugs anddistributor caps.
(b) Secure the high±tension cords with the cord clamps as
shown in the illustration.
(b) Connect the high±tension cords to the ignition coils.w Insert the grommet portion into the terminal hole of
the ignition coil.
IG±16
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wAlign the spline of the ignition coil with the spline of
the holder, and slide on the holder.
NOTICE: Check that holder is correctly installed to the
grommet and ignition coil as shown in the illustration. w Check that the lock claw of the holder is engaged
by lightly pulling the holder.
5. INSTALL RH NO.3 TIMING BELT COVER (a) Install the three gaskets to the timing belt cover.
(b) Fit portion A of the timing belt cover, matching it with the
lower high±tension cord cover.
(c) Install the timing belt cover with the three bolts.
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IGNITION SYSTEM High±Tension Cords and Cord ClampsIG±17
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6. INSTALL VSV FOR EVAP SYSTEMInstall the VSV with the two bolts.
7. INSTALL LH NO.3 TIMING BELT COVER (a) Install the three gaskets to the timing belt cover.
(b) Install the cord grommet to the high±tension cord.
(c) Install the cord grommet to the timing belt cover.
(d) Fit portion A of the timing belt cover, matching it with the
lower high±tension cord cover.
(e) Install the timing belt cover with the four bolts.
8. INSTALL RH ENGINE WIRE COVER (a) Fit portions A and B of the engine wire cover, matchingthem with the lower high±tension cord cover and No.3
timing belt cover.
(d) Install the engine wire cover with the bolt.
9. INSTALL LH ENGINE WIRE COVER (a) Connect portions A and B engine wire cover to the wirebrackets.
(b) Set the VSV (for fuel pressure control system) wire in original position.
(c) Fit portions C and D of the engine wire cover, matching them with the lower high±tension cord cover and No.3
timing belt cover.
(d) Install the engine wire cover with the two bolts.
10. INSTALL UPPER HIGH±TENSION CORD COVER (a) Fit portion A of the upper high±tension cover, matchingit with the top of the lower high±tension cord cover.
IG±18
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