LEXUS SC400 1991 Service Repair Manual

PREPARATION
SST (SPECIAL SERVICE TOOLS)
BR03J±04
RECOMMENDED TOOLS
BR0EB±01
BR±4±
BRAKE SYSTEM PREPARATION
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EQUIPMENT
BR03K±03\
 
\

\
Torque wrench
 


\
 
\

\
Micrometer
 

Brake disc
\
 
\

\
Dial indicator
 

Brake disc
\
 
\

\
Vernier calipers 

Brake disc
LUBRICANT
BR03L±03
 

Item 

Capacity 

Classification
 Brake fluid ±± SAEJ1703 or FMVSS No. 116, DOT 3
±
BRAKE SYSTEM PREPARATIONBR±5
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TROUBLESHOOTING
BR03M±06
Use the table below to help you find the cause of the problem. The numbers i\
ndicate the priority of the likely
cause of the problem. Check each part in order. If necessary, replace these parts.
BR±21, 29, 3
7
BR±7
BR±12 BR±49
BR±11
BR±19
BR±44
BR±44 4BR±21, 29, 37
BR±2 1, 29, 37
BR±2 1, 29, 37
BR±2 1, 29, 37
BR±2
1, 29, 37
BR±2 1, 29, 37
BR±2 1, 29, 37
BR±2 1, 29, 37
BR±2 1, 29, 37
BR±2 1, 29, 37
BR±2 1, 29, 37
BR±2 1, 29, 37BR±8
BR±6±
BRAKE SYSTEM TROUBLESHOOTING
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CHECK AND ADJUSTMENT
BR0EC±07
BRAKE PEDAL CHECK AND
ADJUSTMENT
1. CHECK THAT PEDAL HEIGHT IS CORRECT
Pedal height from asphalt sheet:150.4±160.4 mm (5.92±6.31 in.)
If the pedal height is incorrect, adjust it.
2. IF NECESSARY, ADJUST PEDAL HEIGHT
(a) Disconnect the connector from the stop light switch.
(b) Loosen the stop light switch lock nut and remove the stop light switch.
(c) Loosen the push rod lock nut.
(d) Adjust the pedal height by turning the pedal push rod.
(e) Tighten the push rod lock nut.
Torque: 25 N Vm (260 kgf Vcm, 19 ft Vlbf)
(f) Install the stop light switch and turn it until it lightly contacts
the pedal stopper.
(g) Turn the stop light switch back one turn.
(h) Check the clearance (A) between stop light switch and pedal.
Clearance:
0.5±2.4 mm (0.02±0.09 in.)
(i) Tighten the stop light switch lock nut.
(j) Connect the connector to the stop light switch.
(k) Check that the stop lights come on when the brake pedal isdepressed, and go off when the brake pedal is released.
(l) After adjusting the pedal height, check the pedal free±play.
HINT: If clearance (A) between the stop light switch and the
brake pedal stopper has been adjusted correctly, the pedal
freeplay will meet the specifications.
3. CHECK THAT PEDAL FREEPLAY IS CORRECT, AS SHOWN
(a) Stop the engine and depress the brake pedal several times until there is no more vacuum left in the booster.
(b) Push in the pedal by hand until the beginning of the second point of resistance is felt, then measure the distance, as
shown.
Pedal freeplay:
1±6 mm (0.04±0.24 in.)
If incorrect, check the stop light switch clearance. And if the
clearance is OK, then troubleshoot the brake system.
HINT: The freeplay to the first point of resistance is due to the
play between the clevis and pin. It is 1±3 mm (0.04±0.12 in.)
on the pedal.
±
BRAKE SYSTEM CHECK AND ADJUSTMENTBR±7
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4. CHECK THAT PEDAL RESERVE DISTANCE IS CORRECT,
AS SHOWN
Release the parking brake.
With the engine running, depress the pedal and measure the
pedal reserve distance, as shown.
Pedal reserve distance at 490 N (50 kgf, 110.2 lbf):
More than 89 mm (3.50 in.)
If the reserve distance is incorrect, troubleshoot the brake
system.
BRAKE BOOSTER OPERATIONAL TEST
BR03P±0B
1. OPERATING CHECK
(a) Depress the bake pedal several times with the engine off and
check that there is no change in the pedal reserve distance.
(b) Depress the brake pedal and start the engine. If the pedal goes down slightly, operation is normal.
2. AIR TIGHTNESS CHECK
(a) Start the engine and stop it after 1 or 2 minutes. Depress the brake pedal several times slowly. If the pedal goes down the
farthest the 1st time, but gradually rises after the 2nd or 3rd
time, the booster is air tight.
(b) Depress the brake pedal while the engine is running, and stop the engine with the pedal depressed. If there is no
change in the pedal reserve travel after holding the pedal for
30 seconds, the booster is air tight.
BRAKE SYSTEM BLEEDING
BR0ED±04
HINT: If any work is done on the brake system or if air in the
brake lines is suspected, bleed the system of air.
NOTICE: Do not let brake fluid remain on painted sur-
faces. Wash it off immediately.
1. REMOVE RESERVOIR CAP Turn the reservoir cap to the ªopenº side and remove it.
2. FILL RESERVOIR WITH BRAKE FLUID
Fluid: SAE J1703 or FMVSS NO.116DOT3
BR±8±
BRAKE SYSTEM CHECK AND ADJUSTMENT
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3. BLEED MASTER CYLINDERHINT: If the master cylinder has been disassembled or if the
reservoir becomes empty, bleed the air from the master cylin-
der.
(a) Disconnect the brake lines from the master cylinder.
(b) Slowly depress the brake pedal and hold it.
(c) Block off the outer holes with your fingers, and release the brake pedal.
(d) Repeat (b) and (c) 3 or 4 times.
4. BLEED BRAKE LINE
(a) Connect the vinyl tube to the brake caliper.
(b) Depress the brake pedal several times, then loosen the
bleeder plug with the pedal held down.
(c) At the point when fluid stops coming out, tighten the bleeder plug, then release the brake pedal.
(d) Repeat (b) and (c) until all the air in the fluid has been bled
out.
(e) Repeat the above procedure to bleed the air out of the brake
line for each wheel.
Torque: 11 N Vm (110 kgf Vcm, 8 ft Vlbf)
5. CHECK FLUID LEVEL IN RESERVOIR
Check the fluid level and add fluid if necessary.
Fluid:
SAE J1703 or FMVSS NO.116DOT3
6. INSTALL RESERVOIR CAP
(a) Align the matchmark on the reservoir cap with the matchmark
on the ªopenº side of reservoir.
(b) Push down on the reservoir cap and turn it clockwise until it locks.
(c) Check that the matchmark on the reservoir cap is now aligned with the matchmark on the ªcloseº side of the
reservoir.
±
BRAKE SYSTEM CHECK AND ADJUSTMENTBR±9
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TRAC CONTROL SYSTEM BLEEDING
BR0EE±03
1. BLEED TRACTION CONTROL SYSTEMCAUTION:
w The fluid is under high pressure, and could spray out with
great force, so exercise caution.
w When repairing the brake master cylinder or TRAC
system, bleed the air out of the TRAC system.
(a) Connect a vinyl tube to the bleeder plug of accumulator, then
loosen the bleeder plug.
(b) Start the engine to allow the TRAC pump motor to operate
until all the air has been bled out of the fluid.
(c) Tighten the bleeder plug and stop the engine.
Torque: 8.3 N Vm (85 kgf Vcm, 74 in. Vlbf)
(d) C onnect a vinyl tube to the bleeder plug of the TRAC
actuator, then loosen the bleeder plug.
(e) Start the engine to allow the TRAC pump motor to operate
until all the air has been bled out of the fluid.
(f) Tighten the bleeder plug and stop the engine. Torque: 8.3 N Vm (85 kgf Vcm, 74 in. Vlbf)
(g) Check if any diagnostic trouble code is output which indicates
trouble. If there is, clear the diagnostic trouble code.
2. CHECK FLUID LEVEL IN RESERVOIR Check the fluid level and add fluid if necessary.
Fluid:
SAE J1703 or FMVSS NO. 116DOT3
HINT: Add fluid with the engine idling.
BR±10
±
BRAKE SYSTEM CHECK AND ADJUSTMENT
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PARKING BRAKE CHECK AND
ADJUSTMENT
BR03R±04
1. CHECK THAT PARKING BRAKE LEVER TRAVEL IS
CORRECT
Pull the parking brake lever all the way up, and count the
number of clicks.
Parking brake lever travel at 196 N (20 kgf, 44.1 lbf):
5±8 clicks
If incorrect, adjust the parking brake.
2. IF NECESSARY, ADJUST PARKING BRAKE HINT: Before adjusting the parking brake, make sure that the
rear brake shoe clearance has been adjusted.
For shoe clearance adjustment, see page BR±49.
(a) Remove the cup holder.
(b) Using a socket driver and spanner wrench, remove the adjusting lock nut.
HINT: Tape the socket driver before use.
(c) Turn the adjusting nut until the lever travel is correct.
(d) Install the adjusting lock nut.
(e) Using a socket driver and s panner wrench, tighten the
adjusting lock nut.
Torque: 5.4 N Vm (55 kgf Vcm, 48 in. Vlbf)
(f) Install the cup holder.
±
BRAKE SYSTEM CHECK AND ADJUSTMENTBR±11
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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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5. REMOVE MASTER CYLINDER
(a) Remove the nuts and clamp.
(b) Remove the master cylinder and gasket from the brakebooster.
±
BRAKE SYSTEM MASTER CYLINDERBR±13
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