engine LEXUS SC400 1991 Service User Guide

[4] DIAGNOSTIC CODE CHART
The inspection procedure is shown in the table below. This table permits efficient and accurate troubleshooting
using the trouble codes displayed in the diagnostic code check. Proceed with \
troubleshooting in accordance
with the inspection procedure given in the diagnostic chart corresponding to the trouble codes displayed. The
engine diagnostic code chart is shown below as an example.
IN±22±
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.
±
INTRODUCTION How to Troubleshoot ECU Controlled SystemsIN±25
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SERVICE SPECIFICATIONS
SERVICE DATA
Idle speedMagnetic clutch no engagedApprox. 700 rpm
Magnetic clutch engaged Approx. 700 rpm
Magnetic clutch clearance0.5 + 0.15 mm0.020 + 0.006 in.
TORQUE SPECIFICATIONS
Part tightenedN Vmkgf Vcmft Vlbf
Suction hose X Compressor2525018
Discharge hose X Compressor25250 18
Compressor X EngineBolt 49500 36
Nut 29300 22
Liquid tube X Receiver10100 7
Liquid tube X Condenser10100 7
Discharge tube X Condenser10100 7
Expansion valve X Evaporator5.455 48 in. Vlbf
Suction tube X A/C Unit10100 7
Liquid tube X A/C Unit10100 7
Equalizer tube X EPR25250 18
Pressure switch X Liquid tube101007
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AIR CONDITIONING SYSTEM Service SpecificationsAC±141
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R±12 AIR CONDITIONER SYSTEM RETROFIT ± AC001±98 April 3, 1998
Page 3 of 4
A. Refrigerant handling
1. Do not handle refrigerant in an enclosed area or near an open flame.
2. Always wear eye protection.
3. Avoid getting liquid refrigerant in your eyes or on your skin.
4. Never heat a container with an open flame.
5. Keep containers below 104 °F.
6. When heating a refrigerant can with water, keep the valve above water.
7. Never reuse empty service cans.
B. Replacing parts 1. Plug off any open connections to prevent the entry of moisture and dust.
2. Do not remove plugs from Receiver ports until it is ready for installati\
on.
C. Tightening connecting parts
1. Apply a few drops of ND±Oil 8 compressor oil to O±ring fittings be\
fore tightening.
2. Avoid twisting refrigerant piping when installing R134a service fitting a\
dapters.
3. Tighten all fittings to specified torque.
D. Recharging with A/C ªonº
1. Never open the high side valve with the engine running.
2. Never run the A/C system when low on refrigerant as compressor damage ma\
yoccur.
3. Never charge the system with liquid refrigerant with the engine running.\
4. Be careful not to overcharge the system.
NOTE:
Oil removed during R±12 evacuation should not be used with an R134a Syst\
em.
A. Vehicle Inspection:
Ensure the integrity of the A/C system before proceeding with retrofit.
B. Recover R±12 using R±12 recovery/recycling/recharging equipment: Follow Lexus recommended procedure.
C. Install R134a service fitting adapters: 1. Remove valve cores from R±12 service fittings and discard.
2. Clean external threads of the R±12 service fittings.
3. Apply adhesive to threads (Loctite 262 or equivalent), screw on R134a \
adapterfittings, and tighten to 13 ft±lb.
NOTE:
Vehicles with more than 2 service fittings will require the installation \
of additional
adaptors. All service fittings must have R134a adaptors installed.
D. Replace piping and hose O±rings:
1. Disconnect discharge hose from compressor.
2. Remove and discard old O±rings.
3. Lubricate with ND±Oil 8 and install new O±rings.
4. Disconnect discharge hose from condenser.
5. Lubricate and install retrofit O±rings with ND±Oil 8.
6. Reconnect hoses and torque to specification. (Specifications can be fou\
nd in applicable manuals/guides.)
Service
Precautions
Repair
Procedure
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wTighten the O±ring fittings or the bolted type fittings to
the specified torque.
Precautions When Charging Refrigerant
1. DO NOT OPERATE COMPRESSOR WITHOUT ENOUGH
REFRIGERANT IN REFRIGERANT CYCLE
If there is not enough refrigerant in the refrigerant cycle, oil
lubrication will be insufficient and compressor burnout may
occur, so take care to avoid this.
2. DO NOT OPEN HIGH PRESSURE VALVE OF MANIFOLD GAUGE WITH COMPRESSOR OPERATING
If the high pressure valve is opened, refrigerant flows in the
reverse direction and could cause the charging cylinder to
rupture, so open and close the low pressure valve only.
3. BE CAREFUL NOT TO OVERCHARGE WITH REFRIGERANT IN SYSTEM
If refrigerant is overcharged, it causes trouble such as insuffi-
cient cooling, poor fuel economy, engine overheating etc.
Electrical Parts
Before removing and inspecting the electrical parts, set the
ignition switch to the LOCK position and disconnect the neg-
ative (±) terminal cable from the battery.
CAUTION: Work must not be started until after at least 20
seconds or longer from the time the negative (±) terminal
cable is disconnected.
SRS Airbag System
Failure to carry out service operations in the correct se-
quence could cause the airbag system to deploy, possibly
leading to a serious accident.
When removal or installation of the parts and the yellow wire
harness and connector for the airbag is necessary, refer to
the precautionary notices in the AB section before perform-
ing the operation.
±
AIR CONDITIONING SYSTEM General DescriptionAC±5
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Air Flow Mode Control System
(When the AUTO Switch is ON)
(a) The desired temperature is set using the TEMP switch.
(b) From the input signals (room temperature sensor, ambient temperature sensor and solar sensor) and thetemperature setting, the air conditioner control ECU determines the air flow mode a\
nd outputs signals to
the mode servomotor and max cool servomotor.
(c) When it receives signals from the ECU, the servomotors open or close each of\
the dampers to change the air flow mode.
(When the AUTO Switch is OFF)
The ECU fixes the air flow mode in accordance with the Manual switch pos\
ition.
(When the Engine is Cold)
If the Mode is set on B/L or FOOT, the ECU forcedly changes the air vent to DEF if cold signals are input from
the water temperature sensor.
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AIR CONDITIONING SYSTEM DescriptionAC±11
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4. INSPECT REFRIGERATION SYSTEM FOR LEAKSHINT: After evacuating the air in system, check the system for
leakage.
(a) Open the high pressure hand valve to charge the system with refrigerant.
(b) When the low pressure g auge indicates 98 kPa (1
kgf/cm, 14 psi), close the high pressure hand valve.
(c) Using a gas leak tester, check the system for leakage. If leak is found, repair the faulty component or connection.
5. CHARGE EMPTY REFRIGERATION SYSTEM WITH REFRIGERANT (LIQUID)
HINT: This step is used to charge an empty system through
the high pressure side with refrigerant in a liquid state.
NOTICE:
wNever run the engine when charging the system
through the high pressure side with refrigerant in a
liquid stae.
w Do not open the low pressure hand valve when the
system is being charged with liquid refrigerant.
(a) Open the high pressure hand valve fully.
(b) Charge the system with specified amount of refrigerant, then close the high pressure hand valve.
HINT:
w A fully charged system is indicated by the sight glass
being free of any bubbles.
w If the low pressure gauge does not show a reading, the
system is clogged and must be repaired.
AC±18
±
AIR CONDITIONING SYSTEM Evacuation Air in Refrigeration
System and Charging with Refrigerant
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6. CHARGE PARTIALLY REFRIGERATION SYSTEM WITHREFRIGERANT (VAPOR)
HINT: This step is used to charge the system through the low
pressure side with refrigerant in a vapor state.
NOTICE: Do not open the high pressure hand valve when
running the engine.
(a) Run the engine at ideling speed and operate the air
conditioner.
(b) Open the low pressure hand valve. NOTICE: Adjust the hand valve so that the low pressure
gauge does not indicate over limited pressure of charg-
ing cylinder.
(c) Close the low pressure hand valve when the sight glass is free of any bubbles and stop the engine.
NOTICE: Be careful not to overcharge the system with re-
frigerant as it may cause of troubles.
7. REMOVE MANIFOLD GAUGE SET FROM SERVICE VA LV E S
See page AC±15
±
AIR CONDITIONING SYSTEM Evacuation Air in Refrigeration
System and Charging with RefrigerantAC±19
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DIAGNOSTIC CODE CHART
If a malfunction code is displayed during the diagnostic code check (sens\
or check), check the circuit listed for
that code in the table below (Proceed to the page given for that circuit.)\
Code No.Diag. Code Detecting Condition
00 Normal
11 *1 Open or short in room temperature sensor circuit.
12 Open or short in ambient temperature sensor circuit.
13 Open or short in evaporator temperature sensor circuit.
14*2 Open or short in water temperature sensor circuit.
21*3 Open in solar sensor circuit.
21*3
 Short in solar sensor circuit.
22*4
 All conditions below are detected for 3 secs. or more.
 (a) Engine rpm : 450 rpm or more.
 (b) Ratio between engine and compressor rpm deviates 20% or more in c\
omparison to normal
operation.
23
 Open in pressure sensor circuit.
 Abnormal refrigerant pressure below 206 kPa (2.1 kgf/cm, 30 psi)
over 2,650 kPa (27 kgf/cm, 385 ps\
i)
31 Short to ground or power source circuit in Air Mix Damper position sens\
or circuit.
32 Short to ground or power source circuit in Air Inlet Damper position se\
nsor circuit.
33 Short to ground or power source circuit in Air Outlet Damper position s\
ensor circuit.
41 Air mix damper position sensor value does not change even if ECU operat\
es air mix servomotor.
42 Air inlet damper position sensor value does not change even if ECU oper\
ates air inlet servomotor.
43 Air outlet damper position sensor value does not change even if ECU ope\
rates air outlet
servomotor.
HINT: *1 If the room temp. is approx. ±20 °C (±4 °F) or lower, code 11 may be output even though the system
is normal.
*2 If the ambient temperature is approx. ±50 °C (±58 °F) or lower, a malfunction code may be output
even though the system is normal.
*3 If the check is being performed in a dark place, diagnostic code 21 (so\
lar sensor circuit abnormal) could be displayed.
In this case, perform diagnostic code check again while shining a light,\
such as an inspection light,
on the solar sensor.
If code 21 is still displayed, there could be trouble in the solar senso\
r circuit
AC±28
±
AIR CONDITIONING SYSTEM Troubleshooting
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STANDARD VALUE OF ECU TERMINAL
TerminalsSymbolsWiringColorConditionStandardValue
A14±1A14±7B ER W±BIG OFF10 ~ 14 V
A14±2 A14±3MH MCV R±YIG OFF13 ~ 19

A14±4A14±5MFRSMRECG G±RIG OFF13 ~ 19

A14±6A14±7IG+ ER±L W±BIG ON10 ~ 14 V
Body
A14±7 
Ground Body
E 
Ground Body
W±B 
GroundAlwaysBelow 1

A14±8A14±9FACE DEFW Y±LIG OFF13 ~ 19

A14±15A14±7ACC EL±R W±BTurn ignition switch ACC10 ~ 14 V
A12±2 A14±7REOST EW±G W±B
IG ON and turn headlight control SW
to TAIL position.
Turn Rheostat volume from most
right to left position.
Most
: 0 ~ 14 V
Right

Most
: 10 ~ 14 V
Left
A12 3 A14 7WV EBY WB
Start
the
MAX
Temp. Control Switch:
COLDBelow 1 V
A12±3 A14±7WV EB±Y W±Btheen-
gine MAX
Temp. Control Switch:
HOT10 ~ 14 V
A12 4 A14 7MGC ELR WB
Start the
engine andA/C switch ONBelow 1 V
A12±4 A14±7MGCEL±R W±Bengine andpush AUTO
SWA/C switch OFF10 ~ 14 V
A12 5 A14 7TC EL WBIG ONHLC SW
Rheostat Most
:
Volume RightBelow 1 V
A12±5 A14±7TCEL W±BH.L.C. SW
: TAIL positionRheostat Turn
:
Volume Left10 ~ 14 V
A12±6 A14±7TAIL EG W±BTurn the light control switch to TAILposition10 ~ 14 V
A12±7A14±7LV EYW±BIG ONPush blower SW to change
the blower speed from 1 to
10.Speed 1: 10 ~ 14 V

Speed 10: Below 2 V
A12±8 A14±7BLR EB±R W±BIG ONTurn the blower motorBelow 1.5 V
A12±9 A14±7HR EL±W W±B
IG ON
Turn the blower motorBelow 1 V
IG ONDon't turn the blower motor10 ~ 14 V
A12 10 A14 7RDFGR ERY WBIG ON
Rear defogger switch ONBelow 1 V
A12±10 A14±7RDFGR ER±Y W±BIG ONRear defogger switch OFF10 ~ 14 V
A13±1 A14±7IGN EBW±BStart the engine10 ~ 14 V
AC±32±
AIR CONDITIONING SYSTEM Troubleshooting
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