tow LEXUS SC300 1991 Service Owner's Guide

B. Inspect EGR valve operation(a) Remove the three bolts and stepping motor from thehousing.
(b) Apply battery voltage to terminal B1 (or B2), and while repeately grounding (*S4)±(S4 and *S3)±(S3 and
*S2)±(S2 and *S1)±(S1 and *S4) in sequence, check
that the valve moves toward the open position.
HINT: Keep the terminal marked with an asterisk (*) grounded
while proceeding to the next grounding.
(c) Apply battery voltage to terminal B1 (or B2), and while repeately grounding (*S1)±(S1 and *S2)±(S2 and
*S3)±(S3 and *S4)±(S4 and *S1) in sequence, check
that the valve moves toward the closed position.
HINT:
w Keep the terminal marked with an asterisk (*) grounded
while proceeding to the next grounding.
w Perform this operation after opening the valve by
performing step (b) above.
If operation is not as specified, replace the EGR valve assem-
bly.
(d) Reinstall the stepping motor to the housing with the three bolts.
7. REINSTALL EGR VALVE (a) Place a new gasket on the EGR valve adaptor.
NOTICE:
w Do not touch the adaptor and EGR valve surfaces of the
gasket with your hand.
w Align the port holes of the gasket and adaptor. Be careful
of the installation direction.
±
EMISSION CONTROL SYSTEMS Exhaust Gas Recirculation (EGR) SystemEC±23
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STEERING COLUMN
DESCRIPTION
SR0EA±02
There are two types of steering column, the manual tilt/manual telescopic one\
, and the power tilt/power
telescopic one.
SR0EB±02
OPERATION
POWER TILT OPERATIONThe power tilt mechanism consists of the control gear assembly, tilt motor, tilt position sensor, tilt and tele-
scopic switch, unlock warning switch and tilt and telescopic ECU.
The control gear assembly consists of the worm wheel, tilt gear, tilt worm and slider. Rotation of the tilt motor
moves the slider towards the tilt worm. The column upper tube is integrated w\
ith the slider and is rotated
up and down by movement of the slider.
SR±4
±
STEERING STEERING COLUMN
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FRONT AIRBAG SENSOR
RS00N±07
1. Never reuse the front airbag sensor involved in a collision when the airbag h\
as deployed. (Replace boththe left and right airbag sensors.)
2. Install the front airbag sensor with the arrow on the sensor facing towa\
rd the front of the vehicle.
3. The front airbag sensor set bolts have been anti±rust treated. When the \
sensor is removed, always replace
the set bolts with new ones.
4. The front airbag sensors is equipped with an electrical connection check me\
chanism. Be sure to lock this mechanism securely when connecting the connector. If the connector is not securely locked, a malfunction
code will be detected by the diagnosis system (See page RS±12).
CENTER AIRBAG SENSOR ASSEMBLY
RSOOR±0A
1. Never reuse the center airbag sensor assembly involved in a collision when the airbag has
deployed.
2. Work must be started after 90 seconds from the time the ignition switch is t\
urned to LOCK position and the negative (±) terminal cable is disconnected from the batter\
y even just loosing the set bolts
of center airbag sensor assembly.
WIRE HARNESS AND CONNECTOR
RSO41±01
The SRS wire harness is integrated with the cowl wire harness assembly. The wires for the SRS wire har-
ness are encased in a yellow corrugated tube. All the connectors for the sys\
tem are also a standard yellow
color. If the SRS wire harness becomes disconnected or the connector becomes broken du\
e to an accident
etc., repair or replace it as shown on page RS±48.
±
SUPPLEMENTAL RESTRAINT SYSTEM GENERAL DESCRIPTIONRS±5
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1. DISCONNECT NEGATIVE (±) TERMINAL CABLE FROMBATTERY
CAUTION: Work must be started after 90 seconds from
the time the ignition switch is turned to the ªLOCKº posi-
tion and the negative (±) terminal cable is disconnected
from the battery.
(See page RS±2)
2. REMOVE ENGINE UNDER COVER
(See page BO±12)
3. REMOVE FRONT AIRBAG SENSOR
(a) Disconnect the connector.
(b) Remove the bolt, the nut and the sensor.
4. INSTALL FRONT AIRBAG SENSOR
(a) Install the sensor with the arrow on the sensor facing toward the front of the vehicle.
Torque: 25 N Vm (260 kgf Vcm, 19 ft Vlbf)
NOTICE:
w Make sure the sensor is installed to the specified torque.
w If the sensor has been dropped, or there are cracks, dents
or other defects in the case, brackets or c onnector,
replace the sensor is removed, always replace the set bolt
and the nut with new one.
w The sensor set bolt and the nut have been anti±rust
treated. When the sensor is removed, always replace the
set bolt and the nut with new ones.
w After installation, shake the sensor to check that there is
no looseness.
w The front sensor is equipped with an electrical
connection check mechanism. Be sure to lock this
mechanism securely when connecting the connector. If
the connector is not securely locked, a malfunction code
will be detected by the diagnosis system.
w Check that the dimensions of the body where the front
airbag sensor is installed match those in the body
dimension drawings in the BODY section.
(The SRS may malfunction, or may not work, if the
dimensions of the sensor mount is not correct.)
5. INSTALL ENGINE UNDER COVER
6. CONNECT NEGATIVE (±) TERMINAL CABLE TO BATTERY
±
SUPPLEMENTAL RESTRAINT SYSTEM FRONT AIRBAG SENSORRS±43
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(d) Wrap the remaining part of sleeve with half of the tapeoverlapping at each turn.
(e) Firmly wrap the tape 2 times or more about 10 mm (0.39 in.)
from the other end of the pressure±contact sleeve, then wrap
the tape back towards the start again and firmly finish winding
the tape around the center of the sleeve.
(f) Fix the corrugated tube to the wire using silicon tape.
(g) After applying the s ilicon tape, apply vinyl tape on the
corrugated tube of repair wire side over to the corrugated
tube of vehicle wire harness side.
5. CONNECT NEGATIVE (±) TERMINAL CABLE TO BATTERY
±
SUPPLEMENTAL RESTRAINT SYSTEM WIRE HARNESS AND CONNECTORRS±51
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If the backlash is not within the specification, adjust the back-
lash. (See page SA±98)
5. MEASURE DRIVE PINION PRELOAD Using SST and a torque wrench, measure the drive pinion
preload using the backlash of the drive pinion and ring gear.
Preload (at start):
0.5±0.8 N Vm (5±8 kgf Vcm, 4.3±6.9 in. Vlbf)
HINT: With vehicles which have run less than 8,000 km
(5,000 miles), the preload may be large.
SST 09229±55010
Maximum preload (at start):
1.8 N Vm (18 kgf Vcm, 16.0 in. Vlbf)
6. CHECK TOTAL PRELOAD
Using SST and a torque wrench, measure the total preload.
SST 09229±55010
Total preload (at start):
In addition to drive pinion preload
0.5±0.8 N Vm (5±8 kgf Vcm, 4.3±6.9 in. Vlbf)
If necessary, disassemble and inspect the differential.
7. CHECK PINION GEAR BACKLASH Measure the pinion gear backlash while holding one side
gear toward the case.
Backlash:
0.05±0.02 mm (0.0020±0.0079 in.)
If the backlash is not within the specification, install the cor-
rect thrust washer. (See page SA±93)
8. CHECK TOOTH CONTACT PATTERN (See page SA±99)
DIFFERENTIAL CARRIER DISASSEMBLY
SA0V4±02
HINT: When fastening the differential carrier to an overhaul
stand, etc., fasten it at the 4 places on the ring gear side
shown in the illustration.
±
SUSPENSION AND AXLE REAR DIFFERENTIALSA±87
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HINT: If the dust cover does not fit tightly against the flange
of the side gear shaft, use a screwdriver to drive it down tight.
DIFFERENTIAL CARRIER ASSEMBLY
SA0V6±04
1. ADJUST DIFFERENTIAL PINION GEAR BACKLASH
(a) Install the proper thrust washers on the side gears.HINT: Using the table below, select thrust washers which will
ensure that the backlash is within specification.
Thrust washer thickness:
 Thickness mm (in.) Thickness mm (in.) 

1.6 (0.063)1.8 (0.071)
 1.7 (0.067)±
(b) Install the side gears, pinion gears, pinion gear thrust
washers and pinion shaft in the differential case.
HINT: Align the holes of the dif ferential case and pinion shaft.
(c) Push the side gear shafts gently into the differential case by hand and install them.
(d) Measure the pinion gear backlash while holding one side gear toward the case.
Backlash:
0.05±0.20 mm (0.0020±0.0079 in.)
If the backlash is not within the specification, install the side
gear thrust washers with different thicknesses.
(e) Remove the side gear shaft.
2. INSTALL RING GEAR ON DIFFERENTIAL CASE
(a) Using a hammer and punch, install the straight pin through the differential case and hole of the pinion shaft.
±
SUSPENSION AND AXLE REAR DIFFERENTIALSA±93
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FRONT AXLE HUB DISASSEMBLY
SA0RL±04
1. REMOVE HUB BEARING CAPUsing a screwdriver, remove the hub bearing cap from the
steering knuckle.
2. REMOVE FRONT AXLE HUB LOCK NUT AND ABS SPEED SENSOR ROTOR
(a) Clamp the axle hub in a soft jaw vise.
HINT: Close vise until it holds hub bolt do not tighten further.
(b) Using a hammer and chisel, loosen the staked part of the lock
nut and remove it.
(c) Remove the sensor rotor.
NOTICE: Take care not to scratch the serrations of the sensor
rotor.
3. REMOVE AXLE SHAFT FROM STEERING KNUCKLE
(a) Remove the 4 bolts and shift the brake dust cover toward the hub side (outside).
(b) Using SST, remove the axle shaft from the steering knuckle. SST 09950±20017
±
SUSPENSION AND AXLE FRONT AXLE HUBSA±19
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(e) The drive shaft is designed to move + 20 mm from the normalposition.
Drive shaft standard length:
RH 598.5 mm (23.563 in.)
LH 553.5 mm (21.791 in.)
8. INSTALL NEW END COVER
(a) Pack grease into the end cover.
Grease capacity:50±55 g (0.11±0.12 lb, 1.8±1.9 oz.)
(b) Remove grease from the surface of the inboard joint facingthe cover.
(c) Glue on a new gasket, with the side with adhesive on it facing
toward the outer race side of the inboard joint.
(d) Align the bolt holes of the cover with those of the inboard joint.
(e) Install the 6 hexagon bolts and washer from the end cover side.
(f) Install the 6 nuts to the boot side.
(g) Using a 10 mm hexagon wrench, tighten the bolts. Do this in
the order shown, and repeat several times.
(h) Check that the claw of the end cover touches the inboard joint.
9. CHECK DRIVE SHAFT Check that operation of the joint is smooth within the sliding
region in the axial direction.
HINT: If a large angle is used for the cross±groove type joint,
the joint will feel like it is catching, but this does not indicate
an abnormality.
±
SUSPENSION AND AXLE REAR DRIVE SHAFTSA±73
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166POWER TILT AND POWER TELESCOPIC
THIS SYSTEM OPERATES WITH BOTH THE TILT FUNCTION AND TELESCOPIC FUNCTION DRIVEN AUTOMATICALLY BY THE MOTOR
AND CONTROLLED BY THE ECU. THE STEERING CAN BE ADJUSTED STEPLESSLY FORWARD AND BACK, AND UP AND DOWN, TO
PROVIDE THE MOST SUITABLE STEERING POSITION FOR EASY DRIVING, WITH AUTOMATIC MOVEMENT OF THE STEERING TO A
POSITION WHICH FACILITATES GETTING IN AND OUT OF THE VEHICLE.
THE DRIVER CAN HAVE THE MOST APPROPRIATE DRIVING POSITION MEMORIZED BY OPERATING THE POWER SEAT AND REMOTE
CONTROL MIRROR TOGETHER WITH THE TILT AND POWER TELESCOPIC STEERING.
CURRENT IS ALWAYS APPLIED THROUGH THE
POWER FUSE TO TERMINAL +B OF THE TILT AND POWER TELESCOPIC ECU AND
THROUGH THE DOME FUSE TO TERMINAL BATT OF TILT AND POWER TELESCOPIC ECU.
WITH THE IGNITION SW TURNED ON, THE CURRENT FLOWS FROM ECU±IG FUSE TO TERMINAL IG AND FROM GAUGE FUSE TO
TERMINAL 9 OF A/T INDICATOR SW.
1. MANUAL TILT OPERATION
WHEN THE IGNITION KEY IS INSERTED INTO THE IGNITION KEY CYLINDER (UNLOCK WARNING SW ON), A SIGNAL IS INPUT TO
TERMINAL UWSW OF TILT AND POWER TELESCOPIC ECU. IF THE MANUAL SW IS PUSHED TO THE ªTILT UPº SIDE, CURRENT
FLOWS FROM TERMINAL VC OF TILT AND POWER TELESCOPIC ECU TO TERMINAL MSW OF TILT AND POWER TELESCOPIC ECU
PASSING THROUGH THE MANUAL SW. (THE ECU DETECTS THE MANUAL SW POSITION BY THE VOLUME OF CURRENT.)
AS A RESULT, TILT AND POWER TELESCOPIC ECU OPERATES AND THE CURRENT TO TERMINAL +B OF ECU FLOWS FROM
TERMINAL TIM+ " TERMINAL 1 OF COMB. SW " TERMINAL 2 OF TILT CONTROL MOTOR " TERMINAL 1 " TERMINAL 10 OF COMB.
SW "TERMINAL TIM± OF TILT AND POWER TELESCOPIC ECU " TERMINAL GND2 "GROUND , AND THE TILT UP FUNCTION
OPERATES AS LONG AS THE MANUAL SW IS PUSHED TO THE ªTILT UPº SIDE.
FOR ªTILT DOWNº OPERATION, WHEN THE MANUAL SW IS PUSHED TO THE DOWN SIDE, THE CURRENT FLOWING FROM ECU TO
MOTOR FLOWS TO TERMINAL TIM± OF TILT AND POWER TELESCOPIC ECU "TERMINAL 10 OF COMB. SW "TERMINAL 1 OF TILT
CONTROL MOTOR "TERMINAL 2 "TERMINAL 1 OF COMB. SW "TERMINAL TIM+ OF TILT AND POWER TELESCOPIC ECU, SO THE
MOTOR ROTATES IN THE REVERSE DIRECTION TO TILT UP OPERATION, AND TILT DOWN OPERATION OCCURS ONLY WHILE THE
MANUAL SW IS BEING PUSHED.
2. MANUAL TELESCOPIC OPERATION
WHEN THE IGNITION KEY IS INSERTED INTO THE IGNITION KEY CYLINDER (UNLOCK WARNING SW ON), A SIGNAL IS INPUT TO
TERMINAL UWSW OF TILT AND TELESCOPIC ECU. WHEN THE MANUAL SW IS PUSHED TOWARD ªTELESCOPIC SHORTº SIDE,
CURRENT FLOWS FROM TERMINAL VC OF TILT AND POWER TELESCOPIC ECU TO TERMINAL MSW OF TILT AND POWER
TELESCOPIC ECU THROUGH THE MANUAL SW.
AS A RESULT, THE TILT AND POWER TELESCOPIC ECU OPERATES AND THE CURRENT TO TERMINAL +B OF TILT AND POWER
TELESCOPIC ECU FLOWS FROM TERMINAL TEM+ OF TILT AND POWER TELESCOPIC ECU "TERMINAL 1 OF COMB. SW "
TERMINAL 2 OF TELESCOPIC CONTROL MOTOR "TERMINAL 1 "TERMINAL 4 OF COMB. SW "TERMINAL TEM± OF TILT AND
POWER TELESCOPIC ECU " TERMINAL GND2 "GROUND , AND ªTELESCOPIC SHORTº OPERATION OCCURS AS LONG AS THE
MANUAL SW IS PUSHED THE TO ªTELESCOPIC SHORTº SIDE.
FOR ªTELESCOPIC LONGº OPERATION, WHEN THE MANUAL SW IS PUSHED TO THE TELESCOPIC LONG SIDE, CURRENT FLOWING
FROM TILT AND POWER TELESCOPIC ECU TO THE MOTOR FLOWS THROUGH TERMINAL TEM± OF TILT AND POWER TELESCOPIC
ECU " TERMINAL 4 OF COMB. SW "TERMINAL 1 OF TELESCOPIC CONTROL MOTOR "TERMINAL 2 " TERMINAL 1 OF COMB. SW
" TERMINAL TEM+ OF TILT AND POWER TELESCOPIC ECU "TERMINAL GND2 "GROUND .
AS A RESULT, THE MOTOR ROTATES IN REVERSE TO THE TELESCOPIC SHORT MODE AND TELESCOPIC LONG OPERATION
OCCURS AS LONG AS THE MANUAL SW IS PUSHED TO THE ªTELESCOPIC LONGº SIDE.
3. AUTO AWAY OPERATION
WHEN THE IGNITION SW IS TURNED FROM ON TO OFF, THE CURRENT STOPS FLOWING FROM ECU±IG TO TERMINAL IG OF TILT
AND POWER TELESCOPIC ECU AND IS INPUT AS A SIGNAL THAT THE IGNITION SW IS OFF. WHEN THE AUTO SW IS TURNED ON, AN
ªAUTO SW ONº SIGNAL IS INPUT TO TERMINAL ASW OF TILT AND POWER TELESCOPIC ECU.
IF THE IGNITION KEY IS REMOVED FROM THE IGNITION KEY CYLINDER (UNLOCK WARNING SW OFF) AT THIS TIME, A SIGNAL IS
INPUT FROM TERMINAL UWSW OF TILT AND POWER TELESCOPIC ECU. ALSO, THE TILT POSITION SENSOR (COMB. SW) INPUTS
INTO TERMINAL TIS OF THE TILT AND TELESCOPIC ECU A SIGNAL OF THE STEERING TILT POSITION JUST BEFORE THE IGNITION
SW (FOR UNLOCK WARNING) IS TURNED FROM ON TO OFF.
AS A RESULT, THE TILT AND POWER TELESCOPIC ECU OPERATES AND THE CURRENT TO TERMINAL +B OF TILT AND POWER
TELESCOPIC FLOWS FROM TERMINAL TIM+ OF TILT AND POWER TELESCOPIC ECU "TERMINAL 1 OF COMB. SW "TERMINAL 2
OF TILT CONTROL MOTOR "TERMINAL 1 "TERMINAL 10 OF COMB. SW "TERMINAL TIM± OF TILT AND POWER TELESCOPIC ECU
" TERMINAL GND2 "GROUND , CAUSING THE MOTOR TO ROTATE SO THAT ªTILT UPº OPERATION OCCURS AUTOMATICALLY.
AT THE SAME TIME, THE CURRENT FROM TERMINAL +B OF TILT AND POWER TELESCOPIC ECU TO TERMINAL TEM+ FLOWS FROM
TERMINAL 1 OF COMB. SW "TERMINAL 2 OF TELESCOPIC CONTROL MOTOR "TERMINAL 1 "TERMINAL 4 OF COMB. SW "
TERMINAL TEM± OF TILT AND POWER TELESCOPIC ECU "TERMINAL GND2 "GROUND , CAUSING THE MOTOR TO ROTATE SO
THAT TELESCOPIC SHORT OPERATION OCCURS ON AUTO AND WITH TILT UP OPERATION OCCURRING SIMULTANEOUSLY ON
AUTO, AUTO AWAY OPERATION OCCURS.
SYSTEM OUTLINE
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