LEXUS SC400 1991 Service Manual PDF

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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±
AIR CONDITIONING SYSTEM TroubleshootingAC±33
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STANDARD VALUE OF ECU TERMINAL (Cont'd)
AC±34±
AIR CONDITIONING SYSTEM Troubleshooting
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WIRING DIAGRAM
±
AIR CONDITIONING SYSTEM TroubleshootingAC±35
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AC±44AC±46AC±48AC±50AC±52AC±54AC±56AC±58AC±60AC±62AC±64AC±66
MATRIX CHART OF PROBLEM SYMPTOMS
If a normal code is displayed during the diagnostic code check (sensor ch\
eck) but the trouble still occurs (reap-
pears), perform out troubleshooting for each problem symptom, checking the circuits for each symptom in the
order given in the table below (Proceed to the page given for each circuit)\
. AC±36
±
AIR CONDITIONING SYSTEM Troubleshooting
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AC±68AC±70AC±72AC±74AC±76AC±78AC±80AC±82AC±84AC±90AC±92AC±96AC±98AC±10
8IN±32AC±100AC±103AC±10
4AC±12
0AC±118AC±122AC±12
5AC±126
HINT:
wIf the instruction ºProceed to next circuit inspection shown on matrix \
chartº is given in the flow chart for each
circuit, proceed to the circuit with the next highest number in the table to con\
tinue the check.
w If the trouble still reappears even though there are no abnormalities in a\
ny of the other circuits, then check
or replace the air conditioner control assembly (contains the ECU).
±
AIR CONDITIONING SYSTEM TroubleshootingAC±37
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LOCATION OF CONNECTORS
LOCATION OF CONNECTORS IN ENGINE COMPARTMENT
AC±38±
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±
AIR CONDITIONING SYSTEM TroubleshootingAC±39
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LOCATION OF CONNECTORS IN INSTRUMENT PANEL
AC±40±
AIR CONDITIONING SYSTEM Troubleshooting
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±
AIR CONDITIONING SYSTEM TroubleshootingAC±41
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