1991 LEXUS SC400 Key buzzer

Troubleshooting
You will find the cause of trouble more easily by properly using the tabl\
e shown below. In this table, the numbers
indicate the order of priority of the causes of trouble. Check each part in the \
order shown. If necessary, replace
the part.
See page
BE±4,21BE±4,21BE±4,20BE±4,20BE±156BE±152BE±180BE±179BE±179 ±±BE±181BE±26BE±79BE±4,20 ±±
Part
name
Trouble
AM1 FuseDOME FuseDOOR FusePOWER FuseTheft Deterrent and Door Lock Control ECUPower Window Main RelaySliding Roof Control RelaySliding Roof SwitchSliding Roof MotorSliding Rood Motor (Stones to foreign material
trapped in motor assembly)Limit SwitchIgnition SwitchDoor Courtesy SwitchECU±IG FuseWire Harness
*1 Sliding roof system does not operate.1234
*2 Sliding roof system does not operate.35467892110
Sliding roof system operates abnormally.1324
Sliding roof system stops operation half way.1342
Buzzer does not sound.123
Buzzer sounds abnormally.1
ªKey±off Sliding Roofº operation does not
operate.124536
*1: Door Lock does not operate
*2: Door Lock is normal
BE±182
±
BODY ELECTRICAL SYSTEM Sliding Roof System
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196
MOON ROOF
1B
5
1I
16
1K
71K 13 2
1D
8 1F
8
1H 10
IP1
20 IP1
15
BZ1
4
BZ1
5 BZ1
1
IJ IF B3
B1
6 3
6
3
M
R
Y±R
W±B
W±B
W±B
W±B
W±B L
R
L±W
B±R
R
Y±R
W±B
R±B
R±W
R±W
R±W
W±B
W±B
B
BR
LG W
W±Y
W±B
B
W±B
W±B B±Y
11 4 5 8 9 12
FROM POWER SOURCE SYSTEM
(
SEE PAGE 56 )
30A
DOOR 15A
ECU±IG10A
DOME
THEFT DETERRENT AND
DOOR LOCK CONTROL E CU
KEY OFF POWER
CIRCUIT
DOOR OPEN DETECTION SW LH
DOOR OPEN DETECTION SW RH
MOON ROOF MOTOR
AND LIMIT SW NO. 1
MOON ROOF CONTROL
RE LAY
MOON ROOF
MOTOR
NO. 2 T8
,
T9
M2
D10
D11
M4 BA
A
8A 2A 20 B8
A
16 A 13 A12
W±B
W±B W±B
45
1326
BUZZER
1 2
21
3
GND MTR+ MTR± IS1 IS2
L
W
Y A
M4
B
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199
6. TILT UP REMINDER SYSTEM
WITH THE IGNITION SW IS TURNED TO ACC OR OFF WITH THE MOON ROOF STILL TILTED UP, KEY OFF MOON ROOF OPERATION
CAUSES CURRENT TO FLOW TO TERMINAL 6 OF THE MOON ROOF CONTROL RELAY FOR A PERIOD OF APPROX. 60 SECONDS OR
UNTIL THE DRIVER'S DOOR OR PASSENGER'S DOOR IS OPENED. WHEN KEY OFF MOON ROOF OPERATION ENDS AND THE
CURRENT FLOW IS STOPPED, THE MOON ROOF CONTROL RELAY RECEIVES A SIGNAL THAT THE IGNITION SW IS OFF. MOON
ROOF LIMIT SW NO. 1 AND NO. 2 ARE OFF AT THIS TIME, SO THE SIGNAL IS INPUT TO TERMINALS 8 AND 9 OF THE MOON ROOF
CONTROL RELAY, INDICATING THAT THE MOON ROOF IS IN THE TILT UP CONDITION. THIS CURRENT TO THE MOON ROOF
CONTROL RELAY FLOWS TO TERMINAL 12 OF RELAY " BUZZER " TERMINAL 11 " GROUND, CAUSING THE BUZZER TO SOUND
FOR APPROX. 8 SECONDS. TO INFORM THE DRIVER THAT THE MOON ROOF IS IN THE TILT UP POSITION.
POWER MAIN RELAY
3±5 : CLOSED WITH IGNITION SW AT ON POSITION
M 2 MOON ROOF CONTROL RELAY
11±GROUND : ALWAYS CONTINUITY 6±GROUND : APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION
4±GROUND : APPROX. 12 VOLTS WITH IGNITION SW ON, AND MOON ROOF CONTROL SW AT CLOSE OR UP POSITION
(EXCEPT APPROX. 200MM (7.9 IN) BEFORE FULLY CLOSED POSITION)
5±GROUND : APPROX. 12 VOLTS WITH IGNITION SW ON, AND MOON ROOF CONTROL SW AT OPEN OR DOWN POSITION
M 3 MOON ROOF CONTROL SW
1±4 : CLOSED WITH MOON ROOF CONTROL SW AT UP POSITION
2±4 : CLOSED WITH MOON ROOF CONTROL SW AT CLOSE POSITION
3±4 : CLOSED WITH MOON ROOF CONTROL SW AT DOWN POSITION
5±4 : CLOSED WITH MOON ROOF CONTROL SW AT OPEN POSITION
4±GROUND : ALWAYS CONTINUITY
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
D1030M 331T 8B29
D1130M4A31T 9A29
M 231M 4B31
: RELAY BLOCKS
CODESEE PAGERELAY BLOCKS (RELAY BLOCK LOCATION)
219ENGINE COMPARTMENT LEFT
: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR
CODESEE PAGEJUNCTION BLOCK AND WIRE HARNESS (CONNECTOR LOCATION)
1B20ENGINE ROOM MAIN WIRE
1D20FRONT DOOR LH WIRE
1F20ROOF WIRE
1H
1I20COWL WIRE1J20COWL WIRE
1K
: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS
CODESEE PAGEJOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)
IP138FRONT DOOR RH WIRE AND COWL WIRE (RIGHT KICK PANEL)
BZ140ROOF WIRE AND MOON ROOF WIRE (FRONT SIDE OF ROOF LEFT)
: GROUND POINTS
CODESEE PAGEGROUND POINTS LOCATION
IF36LEFT KICK PANEL
IJ36RIGHT KICK PANEL
: SPLICE POINTS
CODESEE PAGEWIRE HARNESS WITH SPLICE POINTSCODESEE PAGEWIRE HARNESS WITH SPLICE POINTS
B 140ROOF WIREB 340MOON ROOF WIRE
SERVICE HINTS
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185
CURRENT ALWAYS FLOWS TO TERMINAL 1 OF THE INTEGRATION RELAY THROUGH DOME FUSE.
1. SEAT BELT WARNING SYSTEM
WHEN THE IGNITION SW IS TURNED ON, CURRENT FLOWS FROM THE GAUGE FUSE TO TERMINAL 7 OF THE INTEGRATION RELAY.
AT THE SAME TIME, CURRENT FLOWS TO TERMINAL 9 OF THE RELAY FROM THE GAUGE FUSE THROUGH THE SEAT BELT
WARNING LIGHT. THIS CURRENT ACTIVATES THE INTEGRATION RELAY AND, FOR APPROX. 4±8 SECONDS, CURRENT FLOWING
THROUGH THE WARNING LIGHT FLOWS FROM TERMINAL 9 OF THE RELAY " TERMINAL 10 " GROUND, CAUSING THE WARNING
LIGHT TO LIGHT UP. AT THE SAME TIME AS THE WARNING LIGHT LIGHTS UP, A BUCKLE SW OFF SIGNAL IS INPUT TO TERMINAL 8
OF THE RELAY, THE CURRENT FLOWING TO TERMINAL 7 OF THE RELAY FLOWS FROM TERMINAL 10 " GROUND AND THE SEAT
BELT WARNING BUZZER SOUNDS FOR APPROX. 4±8 SECONDS. HOWEVER, IF THE SEAT BELT IS PUT ON DURING THIS PERIOD
(WHILE THE BUZZER IS SOUNDING), SIGNAL INPUT TO TERMINAL 8 OF RELAY STOPS AND THE CURRENT FLOW FROM TERMINAL 7
OF THE RELAY " TERMINAL 10 " GROUND IS CUT, CAUSING THE BUZZER TO STOP.
2. UNLOCK WARNING SYSTEM
WITH THE IGNITION KEY INSERTED IN THE KEY CYLINDER (UNLOCK SW ON), THE IGNITION SW STILL OFF AND \
DOOR OPEN (DOOR
COURTESY SW ON), WHEN A SIGNAL IS INPUT TO TERMINAL 6 OF THE RELAY, THE INTEGRATION RELAY OPERATES, CURRENT
FLOWS FROM TERMINAL 7 OF THE RELAY " TERMINAL 10 " GROUND AND UNLOCK WARNING BUZZER SOUNDS.
B 4 BUCKLE SW LH
1±2 : CLOSED WITH DRIVER'S LAP BELT IN USE
D10 DOOR COURTESY SW LH
3±6 : CLOSED WITH LH DOOR OPEN
I15 UNLOCK WARNING SW [IGNITION SW]
10±9: CLOSED WITH IGNITION KEY IN CYLINDER
INTEGRATION RELAY
10±GROUND: ALWAYS CONTINUITY6±GROUND: CONTINUITY WITH DRIVER'S DOOR OPEN
5±GROUND: CONTINUITY WITH IGNITION KEY IN CYLINDER
8±GROUND: CONTINUITY WITH DRIVER'S LAP BELT IN USA
9±GROUND: 0 VOLTS FOR 4±8 SECONDS WITH IGNITION SW ON AND APPROX. 12 VOLTS 4±8 SECONDS AFTER IGNITION SW ON
1±GROUND: ALWAYS APPROX. 12 VOLTS
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
B 432C14B28I1529
C12A28D1030
: RELAY BLOCKS
CODESEE PAGERELAY BLOCKS (RELAY BLOCK LOCATION)
219ENGINE COMPARTMENT LEFT
: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR
CODESEE PAGEJUNCTION BLOCK AND WIRE HARNESS (CONNECTOR LOCATION)
1B20ENGINE ROOM MAIN WIRE
1C20FLOOR MAIN
1D20FRONT DOOR LH WIRE
1E20INSTRUMENT PANEL WIRE
1H
1I20COWL WIRE
1J
20COWL WIRE
3A22INSTRUMENT PANEL WIRE3D22INSTRUMENT PANEL WIRE
: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS
CODESEE PAGEJOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)
Ba142FLOOR WIRE AND FRONT SEAT LH WIRE (UNDER THE FRONT LH SEAT)Ba242FLOOR WIRE AND FRONT SEAT LH WIRE (UNDER THE FRONT LH SEAT)
: GROUND POINTS
CODESEE PAGEGROUND POINTS LOCATION
IF36LEFT KICK PANEL
BK40UNDER THE CENTER PILLAR LH
SYSTEM OUTLINE
SERVICE HINTS
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