1991 LEXUS SC400 Section 27 page eg 53

HOW TO USE THIS MANUAL
INDEX
An INDEX is provided on the first page of each sec-
tion to guide you to the item to be repaired.
To assist you in finding your way through the manual,
the Section Title and major heading are given at the
top of every page.
ALPHABETICAL INDEX
An ALPHABETICAL INDEX is also provided at the
end of this manual so that you can rapidly find the
item and page you are searching for.
GENERAL DESCRIPTION
At the beginning of each section, a General Descrip-
tion (Precautions) is given that pertains to all repair
operations contained in that section.
Read these precautions before starting any
repair task.
REPAIR PROCEDURES
Most repair operations begin with an overview il-
lustration. It identifies the components and shows
how the parts fit together.
Example:
PREPARATION
Preparation lists the SST (Special Service Tools), rec-
ommended tools, equipment, lubricant and SSM
(Special Service Materials) which should be prepared
before beginning the operation and explains the pur-
pose of each one.
TROUBLESHOOTING
TROUBLESHOOTING tables are included for each
system to help you diagnose the problem and find the
cause.
The fundamentals of how to proceed with trouble±
shooting are described on page IN±15. Be sure to
read this before performing troubleshooting.
IN±2
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The procedures are presented in a step±by±step format:
wThe illustration shows what to do and where to do it.
w The task heading tells what to do.
w The detailed text tells how to perform the task and gives
other information such as specifications and warnings.
Example:
This format provides the experienced technician with a FAST
TRACK to the information needed. The upper case task
heading can be read at a glance when necessary, and the
text below it provides detailed information. Important specifi-
cations and warnings always stand out in bold type.
REFERENCES
References have been kept to a minimum. However, when
they are required you are given the page to refer to.
SPECIFICATIONS
Specifications are presented in bold type throughout the text
where needed. You never have to leave the procedure to look
up your specifications. They are also found at the end of each
section, for quick reference.
CAUTIONS, NOTICES, HINTS:
w CAUTIONS are presented in bold type, and indicate
there is a possibility of injury to you or other people.
w NOTICES are also presented in bold type, and indicate
the possibility of damage to the com ponent being
repaired.
w HINTS are separated from the text but do not appear in
bold. They provide additional information to help you
efficiently perform the repair.
SI UNIT
The UNIT given in this manual are primarily expressed with
the SI UNIT (International System of Unit), and alternately ex-
pressed in the metric system and in the yard/pound system.
Example:
Torque: 30 N Vm (310 kgf Vcm, 22 ft Vlbf)
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INTRODUCTION How to Use This ManualIN±3
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5. Non±reusable parts(a) Always replace cotter pins, gaskets, O±rings and oilseals etc. with new ones.
(b) Non±reusable parts are indicated in the component
illustrations by the º º symbol.
6. Precoated parts Precoated parts are bolts and nuts, etc. that are coated with
a seal lock adhesive at the factory.
(a) If a precoated part is retightened, loosened or causedto move in any way, it must be recoated with the
specified adhesive.
(b) Recoating of precoated parts
(1) Clean off the old adhesive from the bolt, nut or threads.
(2) Dry with compressed air.
(3) Apply the specified seal lock adhesive to the bolt or nut threads.
(c) P re co a te d pa rts are in d ica te d in th e co m ponent
illustrations by the º
º symbol.
7. When necessary, use a sealer on gaskets to prevent leaks.
8. Carefully observe all specifications for bolt tightening
torques. Always use a torque wrench.
9. Use of special service tools (SST) and special service materials (SSM) may be required, depending on the nature
of the repair. Be sure to use SST and SSM where specified
and follow the proper work procedure. A list of SST and SSM
can be found in the preparation part at the front of each
section in this manual.
10. When replacing fuses, be sure the new fuse has the correct
amperage rating. DO NOT exceed the rating or use one with
a lower rating.
11. Care must be taken when jacking up and supporting the vehicle. Be sure to lift and support the vehicle at the proper
locations (See page IN±33).
(a) If the vehicle is to be jacked up only at the front or rear end, be sure to block the wheels at the opposite end in
order to ensure safety.
(b) After the vehicle is jacked up, be sure to support it on
stands. It is extremely dangerous to do any work on a
vehicle raised on a jack alone, even for a small job that
can be finished quickly.
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HOW TO PROCEED WITH TROUBLESHOOTING
Carry out troubleshooting in accordance with the procedure on the follow\
ing page. Here, only the basic proce-
dure is shown. Details are provided in each section, showing the most effective methods for each circuit. Confirm
the troubleshooting procedures first for the relevant circuit before beginn\
ing troubleshooting of that circuit.


Ask the customer about the conditions and the
environment when the problem occurred.
\b 
Confirm the symptoms and the problem
conditions, and check the diagnostic codes.
(When the problem symptoms do not appear
during confirmation, use the symptom simu-
lation method described later on.)
  
Check the result obtained in Step \b, then
confirm the inspection procedure for the sys-
tem or the part which should be checked us-
ing the diagnostic code chart or the matrix
chart of problem symptoms.

Check and repair the affected system or part
in accordance with the instructions in Step .

After completing repairs, confirm that the
problem has been eliminated.
(If the problem is not reproduced, perform the
confirmation test under the same conditions
and in the same environment as when it oc-
curred for the first time.)
IN±16
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R±12 AIR CONDITIONER SYSTEM RETROFIT ± AC001±98 April 3, 1998
Page 2 of 4
A. Required Equipment:
1. R±12 recovery/recycling/recharging equipment
2. R134a recovery/recycling/recharging equipment
3. Measuring cylinder (for compressor oil)
4. Valve core remover for service valves
5. Air conditioner service tool set
6. Torque Wrench Set, P/N 00002±50284±01, includes the following*: 14 mm 00002±51410±01
17 mm 00002±51710±01
22 mm 00002±52216±01
27 mm 00002±52724±01
B. Required Parts & Materials: **
1. R134a Refrigerant
2. Service Fitting Adaptors
3. Caution Labels
4. ND±OIL 8 compressor oil (PAG type oil)
5. Receiver
6. O±Rings for compressor, line & hose connections ***
7. Loctite 262 or equivalent
* required size dependent upon model.
** see parts information section of this bulletin on page 1.
*** it is not necessary to replace any O±rings on ES 300, SC 300 and SC 400 models\
.
A. Refrigerant and Oil Charges
Oil and refrigerant charge amounts are different after the R±12 system has been
retrofitted to R134a. Refrigerant charge amounts are less, while oil ch\
arge
amounts are greater, compared to R±12 system requirements. Refer to the
ND OIL
8
and CHARGE columns in ªParts Informationº table on page 1 for proper amounts\
.
B. System Performance A slight decrease in system performance may be noticed on some vehicles \
under
certain operating conditions.
C. Refrigerant Pressures
R134a high side pressures are greater than that of R±12 above ambient\
temperatures of 68 °F.
D. Flushing Requirements There is no need to remove or flush R±12 mineral oil from the system.\
Simply
charge the system with the specified amount of ND±Oil 8 to provide pr\
oper
lubrication.
E. Use of Sight Glass Mineral based R±12 oil remains and circulates in the A/C system and d\
oes not
dissolve in R134a refrigerant. This results in a cloudy appearance at th\
e sight
glass making it impossible to judge the refrigerant charge amount by us\
ing the
sight glass method. To prevent misdiagnosis on retrofit vehicles, apply black
paint to the sight glass on block±joint (FF) type Receivers. Union\
±nut joint (BAG)
type retrofit Receivers are manufactured without a sight glass.
Required
Tools &
Materials
Retrofitting Overview
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OKNG
OKNG
INSPECTION PROCEDURE
1Check operation of speedometer.
Drive the vehicle and check if the operation of the speedometer in the c\
ombination meter is normal.
The No. 1 vehicle speed sensor is operating normally if the speedometer dis\
play is normal.C
Hint
Check speedometer circuit. See combination meter
troubleshooting on BE section.
2Check voltage between terminal SPD of ECM connector and body ground.
C
OK
P3. Connect the check harness A to the ECM (See EG section.)
4. Shift the shift lever to N position.
5. Jack up one of the rear wheels.
6. Turn ignition switch ON.
Measure voltage between terminal SPD of ECM con-
nector and body ground when he rear wheel is turned
slowly.
Voltage is generated intermittently.
Check speedometer circuit. See combination meter
troubleshooting on BE section.
Proceed to next circuit inspection shown on ma-
trix chart (See page AT±66).
However, when diag. trouble code 42 is displayed,
check and replace ECM.
AT±80±
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NGOK
OKNG
INSPECTION PROCEDURE
1Check resistance between terminals SP2+ and SP± of ECM connector.
C
OK
PConnect the check A to the ECM. (See EG section).
Check resistance between terminals SP
+ and SP2± of
ECM connector.
Resistance: 560 ± 680

Proceed to next circuit inspection shown on matrix chart
(See page AT±66).
2Check No.2 vehicle speed sensor.
C
OK
Hint
P
OK
C
Remove No.2 vehicle speed sensor from transmission.
(See page AT±17).
Measure resistance between terminals 1 and 2 of speed
sensor.
Resistance: 560 ± 680

Reference
Check the vehicle speed sensor's function
Check voltage between terminals 1 and 2 of the vehicle
speed sensor when a magnet is put close to the front
end of the vehicle speed sensor then taken away quick-
ly.
Voltage is generated intermittently.
The voltage generated is extremely low.
Replace No.2 vehicle speed sensor.
Check and repair harness and connector between
ECM and No.2 vehicle speed sensor (See page
IN±33).
AT±88±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTING
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OKNG
OKNG
OKNG
INSPECTION PROCEDURE
1Main throttle position signal check.
C
OK
Hint
PTurn ignition switch ON (Do not start the engine).
Check voltage at the terminal T
T of the DLC2 while grad-
ually depressing the accelerator pedal from the fully
closed position to the fully opened position.
Voltage changes from 0 V to 8 V by stages.
Do not depress the brake pedal during this test. The
voltage will stay at 0 V if depressed.
Proceed to next circuit inspection shown on matrix chart
(See page AT±66).
2Check throttle position sensor.
See engine troubleshooting section in EG section.
Replace throttle position sensor.
3Check harness and connector between ECM and throttle position sensor (S\
ee page IN±33).
Repair or replace harness or connector.
Check and replace ECM.
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A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±103
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