ect LEXUS SC300 1991 Service Owner's Manual

[5] MATRIX CHART OF PROBLEM SYMPTOMS
The suspect circuits or parts for each problem symptom are shown in the tab\
le below. Use this table to trouble-
shoot the problem when a ºNormalº code is displayed in the diagnostic code check but\
the problem is still occur-
ring. Numbers in the table indicate the inspection order in which the circuit\
s or parts should be checked.
HINT: When the problem is not detected by the diagnostic system even though t\
he problem symptom is present,
it is considered that the problem is occurring outside the detection ran\
ge of the diagnostic system, or that the
problem is occurring in a system other than the diagnostic system.
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INTRODUCTION How to Troubleshoot ECU Controlled SystemsIN±23
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6 CIRCUIT INSPECTION
How to read and use each page is shown below.
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INTRODUCTION How to Troubleshoot ECU Controlled Systems
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Location of Connectors in Engine Compartment
wLocation of connectors
This diagram shows the wire harnesses and connectors used in one system.\
The connector shows the harness side connector, so when checking the part side connector (sensor, ac-
tuator, etc.), be careful not to mistake the terminal positions.
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INTRODUCTION How to Troubleshoot ECU Controlled SystemsIN±25
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HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION
PROCEDURE
1. For troubleshooting, diagnostic code charts or problem symptom charts are p\
rovided for each circuit withdetailed inspection procedures on the following pages.
2. When all the component parts, wire harnesses and connectors of each circuit \
except the ECU are found to be normal in troubleshooting, then it is determined that the problem \
is in the ECU.
Accordingly, if diagnosis is performed without the problem symptoms occurring, the \
instruction will be to
check and replace the ECU, even if the problem is not in the ECU. So, al\
ways confirm that the problem
symptoms are occurring, or proceed with inspection while using the sympt\
om simulation method.
3. The instructions ºCheck wire harness and connectorº and ºCheck and\
replace ECUº which appear in the inspection procedure, are common and applicable to all diagnostic codes.\
Follow the procedure outlined
below whenever these instructions appear.
Check Wire Harness and Connector
The problem in the wire harness or connector is an open circuit or a short \
circuit.
OPEN CIRCUIT:
This could be due to a disconnected wire harness, faulty contact in the conn\
ector, a connector terminal pulled
out, etc.
HINT:
1. It is rarely the case that a wire is broken in the middle of it. Most cases occur at the connector. Inparticular, carefully check the connectors of sensors and actuators.
2. Faulty contact could be due to rusting of the connector terminals, to foreign materials entering terminals or a drop in the contact pressure between the male and female terminals of th\
e connector.
Simply disconnecting and reconnecting the connectors once changes the conditio\
n of the
connection and may result in a return to normal operation.
Therefore, in troubleshooting, if no abnormality is found in the wire harness and \
connector check, but the prob-
lem disappears after the check, then the cause is considered to be in th\
e wire harness or connectors.
SHORT CIRCUIT:
This could be due to a short circuit between the wire harness and the body ground or t\
o a short inside the switch,
etc.
HINT:
w When there is a short between the wire harness and body ground, check thorou\
ghly whether the wire
harness is caught in the body or is clamped properly.
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INTRODUCTION How to Troubleshoot ECU Controlled SystemsIN±27
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1. CONTINUITY CHECK (OPEN CIRCUIT CHECK)(1) Disconnect the connectors at both ECU and sensor sides.
(2) Measure the resistance between the applicable terminalsof the connectors.
Resistance: 1
or less
HINT:
w Measure the resistance while lightly shaking the wire
harness vertically and horizontally.
w When tester probes are inserted into a connector, insert
the probes from the back. For waterproof connectors in
which the probes cannot be inserted from the back, be
careful not to bend the terminals when inserting the
tester probes.
2. RESISTANCE CHECK (SHORT CIRCUIT CHECK) (1) Disconnect the connectors at both ends.
(2) Measure the resistance between the applicable terminalsof the connectors and body ground. Be sure to carry out
this check on the connectors on both ends.
Resistance: 1 M
or higher
HINT: Measure the resistance while lightly shaking the wire
harness vertically and horizontally.
3. VISUAL CHECK AND CONTACT PRESSURE CHECK (a) Disconnect the connectors at both ends.
(b) Check for rust or foreign material, etc. on the terminalsof the connectors.
(c) Check crimped portions for looseness or damage and check if the terminals are secured in the lock position.
HINT: The terminals should not come out when pulled lightly.
(d) Prepare a test male terminal and insert it in the female
terminal, then pull it out.
HINT: When the test terminal is pulled out more easily than
others, there may be poor contact in that section.
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Actual examples of the inspection method for open circuit and short circuit ar\
e explained below.
1. OPEN CIRCUIT CHECKFor the open circuit in the wire harness in Fig. 1, perform º(a) Conti\
nuity Checkº or º(b) Voltage Checkº to
locate the section.
(a) Continuity Check
(1) Disconnect connectors (A) and (C) and measure the resistance between\
them.In the case of Fig. 2,
Between terminal 1 of connector (A) and terminal 1 of connector (C) \
±> No continuity (open)
Between terminal 2 of connector (A) and terminal 2 of connector (C) \
±> Continuity
Therefore, it is found out that there is an open circuit between terminal 1 of con\
nector (A) and terminal 1
of connector (C).
(2) Disconnect connector (B) and measure the resistance between connectors\
(A) and (B), (B) and (C).In the case of Fig. 3,
Between terminal 1 of connector (A) and terminal 1 of connector (B) \
±> Continuity
Between terminal 1 of connector (B) and terminal 1 of connector (C) \
±> No Continuity (open)
Therefore, it is found out that there is an open circuit between termina\
l 1 of connector (B) and terminal 1
of connector (C).
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INTRODUCTION How to Troubleshoot ECU Controlled SystemsIN±29
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(b) Voltage CheckIn a circuit in which voltage is applied (to the ECU connector terminal)\
, an open circuit can be checked for
by conducting a voltage check.
(1) As shown in Fig. 4, with each connector still connected, measure the voltage between\
body ground andterminal 1 of connector (A) at the ECU 5V output terminal, terminal 1 of conne\
ctor (B), and terminal
1 of connector (C), in that order.If the results are:
5 V: Between Terminal 1 of connector (A) and Body Ground
5 V: Between Terminal 1 of connector (B) and Body Ground
0 V: Between Terminal 1 of connector (C) and Body Ground
then it is f ound out that there is an open circuit in the wire harness between termi\
nal 1 of (B) and termi-
nal 1 of (C).
2. SHORT CIRCUIT CHECK If the wire harness is ground shorted as in Fig. 5, locate the section by \
conducting a ºcontinuity check with
groundº.
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(a) Continuity Check with Ground
(1) Disconnect connectors (A) and (C) and measure the resistance between terminals 1 and 2 of connector(A) and body ground.
In the case of Fig. 6,
Between terminal 1 of connector (A) and body ground ±> Continuity
Between terminal 2 of connector (A) and body ground ±> No continuit\
y (open)
Therefore, it is found out that there is a short circuit between terminal 1 of con\
nector (A) and terminal 1 of
connector (C).
(2) Disconnect connector (B) and measure the resistance between terminal 1 of connec\
tor (A) and bodyground, and terminal 1 of connector (B) and body ground.
Between terminal 1 of connector (A) and body ground ±> No continuit\
y (open)
Between terminal 1 of connector (B) and body ground ±> Continuity
Therefore, it is found out that there is a short circuit between terminal 1 of con\
nector (B) and terminal 1 of
connector (C).
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Check and Replace ECU
First check the ECU ground circuit. If it is faulty, repair it. If it is nor-
mal, the ECU could be faulty, so replace the ECU with a known
good one and check if the symptoms appear.
(1) Measure the resistance between the ECU ground terminal and the body ground.
Resistance: 1
or less
(2) Disconnect the ECU connector, check the ground terminals on the ECU side and the wire harness side for bend and
check the contact pressure.
IN±32
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Lexus Supports ASE CertificationPage 1 of 4
Title:
R-12 AIR CONDITIONER SYSTEM
RETROFIT
Models:
'90±'93 ES 250/300, SC 400/300, LS 400
Technical Service
Information Bulletin
April 3, 1998
AC001±98
The following information should be used for guidance when retrofitting veh\
icle air
conditioning systems from R±12 to R134a refrigerant.
1990±1992 model year LS 400, 1990±1991 model year ES 250, 1992±1993 model
year ES 300, 1992±1993 model year SC 300, 1992±1993 model year SC 400
All parts required for retrofit are available through the normal parts s\
ystem:
IDENTIFICATIONREQUIRED PARTS & MATERIALS
MODELCOMPRESSORRETROFIT SETRECEIVERND OIL 8CHARGE
LS 40010PA2088471±16050170 cc1000 g
ES 25010PA17V88840±33020 (1)
l
88471±12040100 cc650 g
ES 300plus
90099±14044 (2)SC 30010PA1790099±14044 (2)
90099±14045 (1)88471±16050150 cc900 g
SC400
90099 14045 (1)g
NOTE:
Retrofit Set 88840±33020 includes: 88374±33010 Low pressure side service fitting adaptor (7/16±20 UNF)
88374±33020 High pressure side service fitting adaptor (3/8±20 UNF)
88723±20040 R134a ªUSE ONLYº label (ND Oil 8 for 10P, 10PA compressor)
88723±33050 Retrofit Caution Label
90099±14046 Piping O±rings for discharge hose (quantity 2)
Required for all models (not included in set): 90099±14044 Receiver O±rings (quantity 2)
08885±09107 ND±Oil 8
Also available as needed: 88374±33040 L±shaped low pressure side service fitting adaptor
88374±33050 L±shaped high pressure side service fitting adaptor
OP CODENWCDESCRIPTIONTIMEOPNT1T2
Not Applicable to Warranty
Affected Vehicles page 1 . . . . . . . . . .
Service Precautions page 3 . . . . . . . .
Retrofit Kit Parts page 1 . . . . . . . . . . .
Required Parts page 2 . . . . . . . . . . . . . Required Tools & Materials page 2
. . .
Retrofitting Overview page 2 . . . . . . . . .
Repair Procedures page 3 . . . . . . . . . . .
Warranty Information page 1 . . . . . . . . .
HEATING & AIR CONDITIONING
Introduction
Affected
Vehicles
Parts
Information
Warranty
Information
Table of
Contents
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