1991 LEXUS SC400 parking brake

System Description ± Headlights
DAYTIME RUNNING LIGHT SYSTEM
The Daytime Running Light (DRL) system is activated when engine is started (However, if the parking brake
lever is engaged when the engine is started, the DRL will not light up a\
fter the engine has started. Once the
parking brake is released, the DRL will then light up and will remain on regardless of operation of\
the parking
brake lever).
The DRL remain on until the ignition switch is turned off.
BE±30±
BODY ELECTRICAL SYSTEM Lighting System
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(Canada)
Check forTester connectionConditionSpecified value
ContinuityA4±GroundPassenger's CourtesyOFFNo continuityygy
ONContinuity
A5±GroundIgnition KeyPull offNo continuitygy
Put inContinuity
A6±GroundDriver's CourtesyOFFNo continuityy
ONContinuity
A8±GroundSeat BeltUnfastenContinuity
FastenNo continuity
A10±GroundConstantContinuity
A12±GroundConstantContinuity
B1±GroundPassenger's DoorUnlockContinuityg
LockNo continuity
B2±GroundParking Brake
Switch PositionOFF (Switch pin
pushed in)No continuity
ON (Switch pin re-
leased)Continuity
B3±GroundDriver's DoorUnlockContinuity
LockNo continuity
B7±GroundHeadlight Dimmer
Switch PositionLow Beam or High
BeamNo continuity
FlashContinuity
B8±GroundHeadlight DimmerLow BeamNo continuityg
Switch PositionHigh Beam or FlashContinuity
B10±GroundLight Control SwitchOFFNo continuityg
HEAD or TAILContinuity
B12±GroundConstantContinuity
B13±GroundLight Control SwitchOFF or TAILNo continuityg
HEADContinuity
VoltageA1±GroundConstantVoltageg
A2±GroundConstant*Voltage
A7±GroundIgnition SwitchONVoltageg
LOCK or ACCNo voltage
A9±GroundIgnition SwitchON*Voltageg
LOCK or ACCNo voltage
A11±GroundIgnition SwitchON or ACCVoltageg
LOCKNo voltage
B4±GroundEngineSTOPNo voltageg
RunningVoltage
B11±GroundConstantVoltage
* There is resistance because this circuit is grounded through the bulb.\
If the circuit is as specified, trying replacing the relay with a
new one.
If the circuit is not as specified, refer to BE±35 wiring diagram
and inspect the circuit connected to other parts.
BE±50
±
BODY ELECTRICAL SYSTEM Light System
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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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SERVICE SPECIFICATIONS
SERVICE DATA
BR03A±0G\
\
Brake pedal height from asphalt sheet (LHD)  150.4±160.4 mm (5.92±6.31 in.)
\


\
Brake pedal freeplay 




1±6 mm (0.04±0.24 in.)
\


\
Brake pedal reserve distance at 490 N (50 kgf, 110.2
lbf) 





More than 89 mm (3.50 in.)
\
\
Brake booster push rod to piston clearance (w/ SST)  0 mm (0 in.)
\
\
Front brake pad thickness STD 11.0 mm (0.433 in.)
\
\
Front brake pad thickness Limit 1.0 mm (0.039 in.)\


\
Front brake disc thickness (SC 300)
 


STD


28.0 mm (1.102 in.)
\
\
Front brake disc thickness (SC 300) Limit 26.0 mm (1.024 in.)
\
\
Front brake disc thickness (SC 400) STD 32.0 mm (1.260 in.)
\


\
Front brake disc thickness (SC 400) 


Limit

30.0 mm (1.181 in.)
\
\
Front brake disc runout Limit 0.05 mm (0.0020 in.)
\
\
Rear brake disc pad thickness STD 10.0 mm (0.394 in.)
\
\
Rear brake disc pad thickness Limit 1.0 mm (0.039 in.)\


\
Rear brake disc thickness
 


STD


16.0 mm (0.630 in.)
\
\
Rear brake disc thickness Limit 15.0 mm (0.591 in.)
\
\
Rear brake disc runout Limit 0.05 mm (0.0020 in.)
\


\
Rear brake disc inside diameter 


STD

190 mm (7.48 in.)
\
\
Rear brake disc inside diameter Limit 191 mm (7.52 in.)
\
\
Parking brake lining thickness STD 2.5 mm (0.098 in.)
\
\
Parking brake lining thickness Limit 1.0 mm (0.039 in.)\


\
Parking brake lever travel at 196 N (20 kgf, 44.1 lbf)
 




5±8 clicks
\
\
Parking brake clearance between rear shoe and lever  Less than 0.35 mm (0.012 in.)
\


\
Parking brake adjusting shim thickness for rear disc
brake 




0.3 mm (0.012 in.)
\
\
  0.6 mm (0.024 in.)
\


\
 




0.9 mm (0.035 in.)
±
BRAKE SYSTEM SERVICE SPECIFICATIONSBR±229
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TORQUE SPECIFICATIONS
BR03B±0G\
 
\

\
Part tightened
 

N
Vm
 

kgf
Vcm
 

ft
Vlbf
\
 \
Master cylinder x Piston stopper bolts 10 100 7
\
 \
Master cylinder x Reservoir 1.7 17.5 15.2 in. Vlbf
\
 
\

\
Master cylinder x Brake booster 

13 

130 

9
\
 \
Brake tube union nut 15 155 11
\
 \
Brake booster clevis lock nut 25 260 19
\
 \
Brake booster x Pedal bracket 15 150 11\
 
\

\
Bleeder plug (TRAC actuator and TRAC accumulator)
 

8.3
 

85
 

74 in.
Vlbf
\
 \
Bleeder plug 11 11 0 8
\
 \
Front disc brake torque plate x Steering knuckle 11 8 1,200 87
\
 \
Front disc brake cylinder installation bolt 34 350 25\
 
\

\
Front disc brake cylinder x Flexible hose bolt
 

30
 

310
 

22
\
 \
Rear disc brake torque plate x Axle carrier 104 1,065 77
\
 \
Rear disc brake cylinder installation bolt 34 350 25
\
 
\

\
Rear disc brake x Flexible hose union bolt 

30 

310 

22
\
 \
Parking brake lever x Floor 59 600 43
\
 \
Parking brake cable No.1 x Floor 9 80 69 in.
Vlbf
\
 \
Parking brake cable retainer x Floor 5.4 55 48 in. Vlbf\
 
\

\
Parking brake cable clamp x Floor
 

19
 

190
 

14
\
 \
ABS actuator x Actuator bracket 5.4 55 48 in.
Vlbf
\
 \
ABS actuator bracket x Body 19 195 14
\
 
\

\
Front speed sensor installation bolt 

7.8 

80 

69 in.
Vlbf
\
 \
Rear speed sensor installation bolt 7.8 80 69 in. Vlbf
\
 \
TRAC pump bracket x Body 19 195 14
\
 \
TRAC pump or accumulator x Union bolt 46 465 34
BR±230±
BRAKE SYSTEM SERVICE SPECIFICATIONS
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GENERAL DESCRIPTION
BR03E±06
1. Care must be taken to replace each part properly as it could affect the \
performance of the brakesystem and result in a driving hazard. Replace the parts with parts of the same part number or
equivalent.
2. It is very important to keep parts and the area clean when repairing the\
brake system.
3. If the vehicle is equipped with a mobile communication system, refer to the precaution \
in the IN section.
DESCRIPTION
BR03F±03
The service brakes consist of a foot brake which changes rotational energy to therma\
l energy to stop the
vehicle while it is being driven and a parking brake to keep the vehicle from m\
oving while it is parked.
OPERATION
FOOT BRAKE
BR03G±06
When the brake pedal is depressed, a vacuum builds up in the booster whi\
ch amplifies the pedal force,
pressing on the piston in the master cylinder. The piston movement raises the hydraulic pressure in the
cylinder. This hydraulic pressure is then applied to each respective brake cylin\
der, and acts to press the
brake pads against the rotating discs. The resulting friction converts the ro\
tational energy to thermal ener-
gy, stopping the vehicle.
BR±2±
BRAKE SYSTEM OPERATION
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GENERAL DESCRIPTION
BR03E±06
1. Care must be taken to replace each part properly as it could affect the \
performance of the brakesystem and result in a driving hazard. Replace the parts with parts of the same part number or
equivalent.
2. It is very important to keep parts and the area clean when repairing the\
brake system.
3. If the vehicle is equipped with a mobile communication system, refer to the precaution \
in the IN section.
DESCRIPTION
BR03F±03
The service brakes consist of a foot brake which changes rotational energy to therma\
l energy to stop the
vehicle while it is being driven and a parking brake to keep the vehicle from m\
oving while it is parked.
OPERATION
FOOT BRAKE
BR03G±06
When the brake pedal is depressed, a vacuum builds up in the booster whi\
ch amplifies the pedal force,
pressing on the piston in the master cylinder. The piston movement raises the hydraulic pressure in the
cylinder. This hydraulic pressure is then applied to each respective brake cylin\
der, and acts to press the
brake pads against the rotating discs. The resulting friction converts the ro\
tational energy to thermal ener-
gy, stopping the vehicle.
BR±2±
BRAKE SYSTEM OPERATION
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