warning LEXUS SC400 1991 Service Manual PDF

Parts NameFunction
Coolant Level
Warning SwitchThis switch is installed in the radiator reservoir tank. It lights up a \
warning light when the
coolant level becomes low.
Engine Oil Level
Warning SwitchThis switch is mounted in the engine oil pan. It lights a warning light \
when the engine oil
level is low.
Brake Fluid Level
Warning SwitchThis switch is mounted in the brake master cylinder reservoir tank. It l\
ights up a warning
light when the brake fluid level is low.
Parking Brake SwitchThis switch is on the parking brake lever bracket. Continuity in this sw\
itch is established
when the lever is released, causing a warning light to light up.
Door Courtesy SwitchContinuity is established in this switch when a door is opened, causing \
a warning light to
light up.
Warning LightsWhen an abnormality is detected in the vehicle, current is sent to these\
lights, or they are
grounded, causing them to light up.
Indicator LightsCurrent is sent to these lights, or they are grounded, causing them to l\
ight up and indicate
the vehicle's condition to the driver.
Window Washer Level
Warning SwitchThis switch is mounted in the window washer tank. It lights a warning li\
ght when the
window washer level becomes low.
±
BODY ELECTRICAL SYSTEM Cominbation MeterBE±97
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ConnectionCheck forTester connectionConditionSpecified value
A19 A15Trip switch A/BPushContinuity
Trip switchContinuity
A19±A15Trip switch A/BFreeNo continuityTrip switchContinuity
A20 A15Trip switch RESETPushContinuityA20±A15Trip switch RESETFreeNo continuity
DOME
FuseVoltageA11±GroundConstantBattery positive voltage
Speed
SVoltageA13 A15
Ignition
switch
*3 Revolve propeller shaft0V
11 V
SensorVoltageA13±A15switch
ON*3 Stop propeller shaft0V or 11V
C1±GroundPBattery positive voltage
C2±GroundIgnitionRBattery positive voltage
Neutral start
it hVoltageC3±Ground
Ignition
switch
ON andNBattery positive voltageswitchVoltageC4±GroundON and
shift leverDBattery positive voltage
C5±Ground
shift lever
position2Battery positive voltage
C16±Ground
osition
LBattery positive voltage
O/D OFFContinuityC18 GroundO/D OFF switchONContinuity
SwitchContinuityC18±GroundO/D OFF switchOFFNo continuity
AlternatorContinuityC15±GroundEngine stopContinuity
ºLº terminalVoltageC14±GroundEngine runningBattery positive voltage
FuelContinuityA7 GroundFuel remainderFullNo continuity
SenderContinuityA7±GroundFuel remainderEmptyContinuity
GaugeFull, Approx. 79.3 mm
(3.12 in.)Approx. 6

ResistanceA8±C8Float
position1/2, Approx. 193.1 mm
(76.0 in.)Approx. 32.5

Empty, Approx. 308.1 mm
(12.13 in.)Approx. 97

*Window
washer level
ContinuityB9±GroundON (float down)Continuitywasher level
warning
switchContinuityB9 Ground
(Canada)OFF (float up)No continuity
Brake fluidBrake fluid levelON (float down)Continuity
Level warning
Brake fluid level
warning SWOFF (float up)No continuity
SW and
Parking brake
SW
ContinuityC13±GroundParking brake
ON (Depress the Ped-
al))Continuity
SWParking brake
SWOFF (Release the Ped-
al)No continuity
Low oil
PressureContinuityC19 GroundEngine condition
RunningNo continuity
Pressure
Warning SWContinuityC19±GroundEngine conditionStopContinuity
Door courtesyContinuityC12 GroundDriver's andOpen (ON)Continuityy
SwitchContinuityC12±GroundDriver s and
passenger's doorClosed (OFF)No continuity
IGN fuseVoltageC14 GroundIgnition switchONBattery positive voltageVoltageC14±GroundIgnition switchLOCK or ACCNo voltage
CIG fuseVoltageA6 GroundIgnition switchACC or ONBattery positive voltageVoltageA6±GroundIgnition switchLOCK or STARTNo voltage
BE±107±
BODY ELECTRICAL SYSTEM Combination Meter
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ConnectionCheck forTester connectionConditionSpecified value
Turn signalHazard warning switch ONBattery positiveTurn signal
SW andB 16 Ground
Hazard warning switch ONBattery ositive
voltage e 0V
HazardB±16±Ground
IG SW ON and turn signal SW ºLeftºBattery positive
Warning
Si hVoltage
IG SW ON and turn signal SW ºLeftºBattery ositive
voltage e 0V
SwitchVoltage
Hazard warning switch ONBattery positive
B 17 Ground
Hazard warning switch ONBattery ositive
voltage e 0VB±17±Ground
IG SW ON and turn signal SW ºRightºBattery positiveIG SW ON and turn signal SW ºRightºBattery ositive
voltage e 0V
HeadlightLi ht t l SWDimmer SW ºHIº orBattery positiveHeadlight
VoltageB7±GroundLight control SW
ºHEADº
Dimmer SW HI or
ºFlashº
Battery ositive
voltageVoltageB7±GroundºHEADºDimmer SW ºLOºNo voltage
ContinuityB6±GroundLight control SW
º
HEADº
Dimmer SW ºHIº or
ºFlashºContinuityContinuityB6 GroundºHEADºDimmer SW ºLOºNo continuity
IgniterVoltageA9±GroundEngine RunningVoltage
fluctuates
ECT patternVoltageB4 GroundIG SW ON and ECT patternPWRBattery positive voltageECT attern
Select switchVoltageB4±GroundIG SW ON and ECT attern
select SW positionNORMNo voltage
Engine oilOil temperature below approx. 55 5C (131 5F)Continuityg
Level warn-
ing Switch
ContinuityB8±Ground
Oil temperature
above approx. 55 5CON (float up)ContinuitygContinuityB8 Groundabove a rox. 55 C
(131 5F) and SW
positionOFF (float off)No continuity
GAUGE fuseVoltageA1 GroundIgnition switchONBattery positive voltageVoltageA1±GroundIgnition switch
positionLOCK, ACC, STARTNo voltage
Neutral StartVoltageA12±GroundIgnition switch
position
START (ºPº or ºNº
range)Battery positive voltage
switch
VoltageA12 GroundpositionLOCK, ACC, ONNo voltage
ECU±BVoltageC11 GroundIgnition switchONBattery positive voltage
FuseVoltageC11±GroundIgnition switch
positionLOCK, ACC, STARTNo voltage
Rheostat
Li ht t l
ON (Rheostat knob
t d itiBtt ltLight control
VolumeLight control SWturned any position
except fully clock-
Battery voltage or
5V or moreVolume
VoltageA2±Ground
g
HEAD or TAIL and
rheostat volume
except fully clock-
wise)5V or more
VoltageA2 Groundrheostat volume
knob positionOFF (Rheostat knob)
turned fully clockNo voltageknob ositionturned fully clock-
wise)No voltage
GroundA8±GroundConstantContinuity
ContinuityA10±GroundConstantContinuityContinuityA22±GroundConstantContinuity
A23±GroundConstantContinuity
*1 Jack up the vehicle.*2 Shift lever position is ºPº range.
If circuit is not as specified, refer to BE±100 wiring diagrams
and inspect the circuits connected to other parts.
BE±108
±
BODY ELECTRICAL SYSTEM Combination Meter
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TROUBLESHOOTING
How to proceed with troubleshooting
Perform troubleshooting in accordance with the procedure on the followin\
g page.

CUSTOMER PROBLEM ANALYSIS
Using the customer problem analysis check sheet for reference, ask the c\
ustomer in as much detail as
possible about the problem.
CHECK AND CLEAR THE DIAGNOSTIC TROUBLE CODES (PRECHECK)
If the TRAC indicator light lights up, and the TRAC control does not ope\
rate, the ECU stores diagnostic
trouble codes corresponding to the problem in memory.
Before confirming the trouble, first check the diagnostic trouble code for any\
malfunction codes stored in
memory. When there are malfunction codes, make a note of them, then clear them and proceed to ª 
Problem Symptom Confirmationº.
 PROBLEM SYMPTOM CONFIRMATION,  SYMPTOM SIMULATION
Confirm the problem symptoms. If the problem does not reoccur, simulate the problem by initially checking
the circuits indicated by the diagnostic trouble code in step , using ªProblem simulation methodº.
 DIAGNOSTIC TROUBLE CODE CHECK
Check the diagnostic trouble codes. If a malfunction code is output, proceed \
to ª  Diagnostic Trouble
Code Chartº.
If the normal code is output, proceed to ª  Problem Symptoms Chartº.
Be sure to proceed to ª  diagnostic Trouble Code Chartº after steps and  are completed.
If troubleshooting is attempted only by following the malfunction code sto\
red in the memory, errors could
be made in the diagnosis.
 DIAGNOSTIC TROUBLE CODE CHART
If a malfunction code is confirmed in the diagnostic trouble code check,\
proceed to the inspection proce-
dure indicated by the matrix chart for each diagnostic trouble code.
 PROBLEM SYMPTOMS CHART
If the normal code is confirmed in the diagnostic trouble code check, perf\
orm inspection in accordance with
the inspection order in the problem symptoms chart.
 CIRCUIT INSPECTION
Proceed with diagnosis of each circuit in accordance with the inspection\
order confirmed in  and .
Determine whether the cause of the problem is in the sensor, actuators, wire harness and connectors or
the ECU.
\b SENSOR CHECK
Use the ABS warning light to check if each of the signals from speed sensors is \
being input correctly to
the ECU. Instructions for this check are given in the circuit inspection\
.
[10] REPAIRS After the cause of the problem is located, perform repairs by following the i\
nspection and replacement pro-
cedures in this manual.
[11] CONFIRMATION TEST
After completing repairs, confirm not only that the malfunction is eliminated\
, but also conduct a test drive
to make sure the entire TRAC system is operating correctly. And also check the ABS is operating correctly.
BR±166
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)
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DIAGNOSTIC TROUBLE CODE CHART
If a malfunction code is displayed during the diagnostic trouble code chec\
k, check the circuit listed for that code
in the table below and proceed to the page given.
HINT: If the TRAC indicator light lights up and the TRAC indicator light doe\
s not blink when the Diag. code is
checked, check the blinking pattern of the ABS warning light and perform trouble\
shooting of the ABS system.
BR±186BR±189
BR±190
BR±192
BR±196 BR±198
BR±200
BR±208
BR±216
BR±218
BR±220BR±189
BR±189
BR±190
BR±190
BR±190
BR±200 BR±208
*1: If a malfunction is detected, the TRAC OFF indicator light lights up.
*2: Indicator light does not lights up even if an error is detected.
*3: If a malfunction is detected, the TRAC OFF indicator light or TRAC i\
ndicator light light up.
BR±172
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)
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TRAC OFF Indicator, TRAC Cut Switch Circuit
CIRCUIT DESCRIPTION
This is the TRAC control main switch. When the TRAC cut switch is pushed on,\
TRAC control goes off and
the TRAC OFF indicator lights up. This indicator is also used for warnings \
when the trouble occurs.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
BR±222±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)
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BR±150). BE±163
.
IN±33
).
WIRING DIAGRAM
TRAC Indicator Light Circuit
CIRCUIT DESCRIPTION
The TRAC indicator blinks during TRAC operation.
This indicator is also used for warnings when the trouble occurs and for disp\
laying diagnostic trouble codes.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)BR±225
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MASTER CYLINDER
MASTER CYLINDER REMOVAL
BR0EF±03
1. w/ TRAC:DRAIN OUT HIGH PRESSURE FLUID
(a) C onnect a vinyl tube to the bleeder plug of the TRAC
actuator, then loosen the bleeder plug with the ignition switch
in the OFF position.
CAUTION: The fluid is under high pressure, and could spray
out with great force, so exercise caution.
(b) Tighten the plug when fluid stops flowing out.
2. DISCONNECT LEVEL WARNING SWITCH CONNECTOR
3. DRAW OUT FLUID WITH SYRINGE
NOTICE: Do not let brake fluid remain on a painted surface.
Wash it off immediately.
4. DISCONNECT BRAKE LINES Using SST, disconnect the brake lines from the master cylin-
der.
SST 09023±00100
BR±12
±
BRAKE SYSTEM MASTER CYLINDER
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8. INSTALL MASTER CYLINDER BOOTWith the UP mark on the master cylinder boot facing up-
wards, install the cylinder boot on the master cylinder.
MASTER CYLINDER INSTALLATION
BR0EJ±05
1. ADJUST LENGTH OF BRAKE BOOSTER PUSH RODBEFORE INSTALLING MASTER CYLINDER
(See page
BR±19)
2. INSTALL MASTER CYLINDER Install the master cylinder and a new gasket on the brake
booster with 3 nuts.
Torque: 13 N Vm (130 kgf Vcm, 9 ft Vlbf)
3. CONNECT BRAKE LINES
Using SST, connect the brake lines to the master cylinder.
Torque the union nuts.
SST 09023±00100
Torque: 12 N Vm (125 kgf Vcm, 9 ft Vlbf)
4. CONNECT LEVEL WARNING SWITCH CONNECTOR
5. FILL BRAKE R ESERVOIR WITH BRAKE FLUID AND
BLEED BRAKE SYSTEM
(See page BR±8)
6. w/ TRAC:
BLEED TRAC SYSTEM
(See page BR±10)
7. CHECK FOR FLUID LEAKAGE
8. CHECK AND ADJUST BRAKE PEDAL (See page BR±7 )
±
BRAKE SYSTEM MASTER CYLINDERBR±17
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BR0EY±05
ECU TERMINALS STANDARD VALUE
w/o TRAC:
 


Symbols
(Terminals No.) 

STD Voltage (V)\
 
\

\
Condition
 


BAT
(A23±22) 
± 


GND
(A23±13) 


10±14\
 
\

\

Always
 IG
(A23±11) ± GND
(A23±2) 10±14\
 \
IG switch ON
 

SR
(A22±5) 

±
 

R±
(A22±4) 

8.3±14
\
 
\

\
IG switch ON, ABS warning light OFF
 

MR
(A22±11) 

±
 

R±
(A22±4) 

Below 1.0
\
 
\

\
IG switch ON
 


SFR
(A23±1) 

±
 


GND
(A23±2) 

10±14
\
 
\

\
IG switch ON, ABS warning light OFF
 


SFL
(A22±6) 
± 


GND
(A23±13) 

10±14\
 
\

\
IG switch ON, ABS warning light OFF
 


SRR
(A22±12) 
± 


GND
(A23±13) 

10±14\
 
\

\
IG switch ON, ABS warning light OFF
 AST
(A22±8) ± GND
(A23±13) 10±14\
 \
IG switch ON, ABS warning light OFF
 

WA
 

±
 

GND
 

Below 2.0
\
 
\

\
IG switch ON, ABS warning light ON
 
WA
(A23±10) 
±
 
GND
(A23±13) 10±14\
 \
IG switch ON, ABS warning light OFF
 PKB ± GND Below 1.5\
 \
IG switch ON, PKB switch ON
 
PKB
(A23±16) ± 
GND
(A23±13) 10±14\
 \
IG switch ON, PKB switch OFF
 STP 
±
 GND Below 1.5\
 \
Stop light switch OFF
 STP
(A23±7) ± GND
(A23±2) 8±14\
 \
Stop light switch ON
 

D/G
(A23±21) 

±
 

GND
(A23±13) 

10±14
\
 
\

\
IG switch ON, ABS warning light OFF
 


Tc
(A23±17) 

±
 


GND
(A23±13) 

10±14
\
 
\

\
IG switch ON
 


Ts
(A23±6) 
± 


GND
(A23±2) 

10±14\
 
\

\
IG switch ON
 


FR+
(A22±1) 
± 


FR±
(A22±7) 


AC generation\
 
\

\

IG switch ON
Slowly turn right front wheel
 FL+
(A22±3) ± FL±
(A22±10) AC generation\
 \
IG switch ON
Slowly turn left front wheel
 

RR+
(A23±19)
 

±
 

RR±
(A23±20)
 

AC generation
\
 
\

\
IG switch ON
Slowly turn right rear wheel
 

RL+
(A23±14) 

±
 

RL±
(A23±3) 

AC generation
\
 
\

\
IG switch ON
Slowly turn left rear wheel
±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)BR±59
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