1991 LEXUS SC400 wiring

 
Check for Tester connection Condition Specified value
 Voltage A4±Ground Constant Battery positive voltage
  
A3±Ground
 Ignition switch
iti
 ACC or ON Battery positive voltage
  A3±Ground position LOCK No voltage
 Continuity 
A7±Ground
 Luggage compartment
d t it h
 Push (OFF) No continuity  A7±Ground door courtesy switch Free (ON) Continuity
If circuit is not as specified, refer to BE±201, 203 wiring dia-
grams and inspect the circuits connected to other parts.
HINT:
w Check the wire harness between the radio receiver
assembly and the CD auto changer in accordance with
the wiring diagrams in BE±201, 203.
w Since the signals to and from the CDL+, CDL, CDR+,
CDR, TXM+, TXM, TXS+ and TXS terminals are serial
signals, they cannot ordinarily be measured with a
tester.
LUGGAGE COMPARTMENT DOOR
COURTESY SWITCH
(See page BE±82)
±
BODY ELECTRICAL SYSTEM AUDIO SYSTEMBE±213
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HORN SYSTEM
PARTS LOCATION
WIRING AND CONNECTOR DIAGRAMS
BE±262±
BODY ELECTRICAL SYSTEM HORN SYSTEM
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WIRING DIAGRAM
No.SymbolTerminal NameNo.SymbolTerminal NameNo.SymbolTerminal Name
P11
±1SLDFSlide Switch (Forward)P11±13CHKCheckP10±7IGIgnition Switch
2RCLFReclining Switch (Forward)14SSRRReclining Sensor8GND2Ground 2
3FUPFront Vertical Switch (UP)15SSRVRear Vertical Sensor9SLD±Slide Motor (Back)
4RUPRear Vertical Switch (UP)16SSRSSlide Sensor10RCL±Reclining Motor (Down)
5SSFVFront Vertical Switch17SOSerial Communications11FRV±Front Vertical Motor (Down)
6PVCCPosition Sensor Power
Source18SGNDSensor Ground12RRV±Rear Vertical Motor (Down)
7SYSBPower SourceP10±1GNDGround13RRV+Rear Vertical Motor (For-
ward)
8SISerial Communications2SLD+Slide Motor (Forward)14+B2Power Source
9SLDRSlide Switch (Back)3RCL+Reclining Motor (Up)15PNeutral Start Switch
10RCLRReclining Switch (Back)4FRV+Front Vertical Motor (Up)16±±±±
11FDWNFront Vertical Switch (Down)5+BPower Source
12RDWNRear Vertical Switch (Down)6STOPStop Light
BE±272±
BODY ELECTRICAL SYSTEM Power Seat Control System (Driver's Seat)
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STANDARD VALUE OF ECU TERMINAL
TerminalsSymbolsWiringColorConditionStandard Value
P11±1 eBody
GroundSLDF eBody
Ground
LSeat moved forward using slide SWBelow 1 VL
Others10±14 V
P11±2 eBody
GroundRCLF eBody
GroundY±RSeat moved forward using reclining SWBelow 1 V
Others10±14 V
P11±3 eBody
GroundFUP eBody
GroundL±YSeat raised using front vertical SWBelow 1 V
Others10±14 V
P11±4 eBody
GroundRUP eBody
GroundY±GSeat raised using rear vertical SWBelow 1 V
Others10±14 V
P11±5 eP11±18SSFV eSGNDLG±R eBR±BFront vertical operation0 V e8 V
P11±6 eP11±18PVCC eSGNDVe BR±BManual position return operation8 V
P11±7 eP10±1SYSB eGNDRe W±BAlways10±14 V
P11 8SIW
Signals between power seat ECU & tilt
telescopic ECU0 V e12 V
P11±8SIW
OthersResistance
(approx. 2.5 k
)
P11±9 eBody
GroundSLDR eBody
Ground
L±BSeat moved to rear using slide SWBelow 1 VL±B
Others10±14 V
P11±10 eBody
GroundRCLR eBody
Ground
Y±BSeat moved to rear using reclining SWBelow 1 VY±B
Others10±14 V
P11±11 eBody
GroundFDWN eBody
Ground
L±RSeat lowered using front vertical SWBelow 1 VL±R
Others10±14 V
P11±12 eBody
GroundRDWN eBody
Ground
Y±LSeat lowered using rear vertical SWBelow 1 VY±L
Others10±14 V
P11±13CHK
P11±14 eP11±18SSRR eSGNDV±W eBR±BReclining operation0 V e8 V
P11±15 eP11±18SSRV eSGNDY±G eBR±BRear vertical operation0 V e8 V
P11±16 eP11±18SSRS eSGNDLG eBR±BSlide operation0 V e8 V
±
BODY ELECTRICAL SYSTEM Power Seat Control System (Driver's Seat)BE±273
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CIRCUIT INSPECTION
+B Power Source Circuit
CIRCUIT DESCRIPTION
This is the power source for motors such as the slide motor and reclining mo\
tor.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
Check Door fuse.NG
Check for short in all harness and
components connected to the
DOOR fuse (See attached wiring
diagram).
Check voltage between terminals +B, +B2
and GND of ECU connector. OK
OKProceed to next circuit inspection
shown on matrix chart (See page
BE±276
).
Check continuity between terminal GND
of ECU connector and body ground. NG
NGRepair or replace harness or
connector.
OK
Check and repair harness or connector
between ECU and battery.
WIRING DIAGRAM
BE±284±
BODY ELECTRICAL SYSTEM Power Seat Control System (Driver's Seat)
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OKNG
NGOK
OKNG
INSPECTION PROCEDURE
1Check DOOR fuse.
Check for short in all the harness and components con-
nected to the DOOR fuse (See attached wiring diagram).
2Check voltage between terminals +B, +B2 and GND of ECU connector.
C
OK
PRemove ECU with connectors still connected.
Measure voltage between terminals +B, +B2 and GND
of ECU connector.
Voltage: 10 ± 14 V
Proceed to next circuit inspection shown on matrix chart
(See page BE±276.)
3Check continuity between terminal GND of ECU connector and body ground.
C
OK
Measure resistance between terminal GND of ECU and
body ground.
Resistance: 1
or less.
Repair or replace harness or connector.
Check and repair harness or connector between
ECU and battery.
±
BODY ELECTRICAL SYSTEM Power Seat Control System (Driver's Seat)BE±285
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WIRING DIAGRAM
ECU Power Source Circuit
CIRCUIT DESCRIPTION
This circuit provides power for ECU operation and is also the power source f\
or the sensors.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
Check DOME fuse.NGCheck for short in all the harness
and components connected to
DOME fuse.
(See attached wiring diagram).
OK
Check voltage between terminals SYSB
and SGND of ECU connector. Proceed to next circuit inspection
shown on matrix chart
(See page
BE±276).
Check continuity between terminal SGND
of ECU connector and body ground. OK
NG
OK NG
Replace or repair harness or
connector.
Check and repair harness or connector
between ECU and battery.
BE±286±
BODY ELECTRICAL SYSTEM Power Seat Control System (Driver's Seat)
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OKNG
NGOK
OKNG
INSPECTION PROCEDURE
1Check DOME fuse.
Check for short in all the harness and components con-
nected to the DOME fuse (See attached wiring diagram).
2Check voltage between terminals SYSB and SGND of ECU connector.
C
OK
PRemove ECU with connectors still connected.
Measure voltage between terminals SYSB and SGND
of ECU connector.
Voltage: 10 ± 14 V
Proceed to next circuit inspection shown on matrix chart
(See page BE±276).
3Check continuity between terminal SGND of ECU connector and body ground.\
C
OK
Measure resistance between terminal SGND of ECU
connector and body ground.
Resistance: 1
or less.
Repair or replace harness or connector.
Check and repair harness or connector between
ECU and battery.
±
BODY ELECTRICAL SYSTEM Power Seat Control System (Driver's Seat)BE±287
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