ABS LEXUS SC400 1991 Service Owner's Manual

OKNG
NGOK
OKNG
INSPECTION PROCEDURE
1Check voltage between terminals ABSO, BRC, BRP of TRAC ECU and body ground.
C
OK
Hint
PRemove TRAC ECU with connectors still connected.
Measure voltage between terminals ABSO, BRC, BRP
of TRAC ECU and body ground when ignition switch is
turned ON.
Voltage: ABSO, BRC: 6 ± 14 VBRP: About 7 V (Pulse)\
(Reference)
Check and replace TRAC ECU.
2Check voltage between terminals ABSO, BRC, BRP or TRAC ECU and body ground wi\
th TRAC
ECU connector is disconnected.
C
OK
Hint
PDisconnect TRAC ECU connector.
Measure voltage between terminals ABSO, BRC, BRP
or TRAC ECU connector and body ground when ignition
switch is turned ON.
Voltage: See step 1.
Check and replace TRAC ECU.
3Check for open and short in harness and connector between ABS & TRAC ECU and TRAC ECU
(See page IN±33).
Repair or replace harness or connector.
Check and replace ABS & TRAC ECU.
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)BR±221
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NGOK
OKNG
INSPECTION PROCEDURE
1Check voltage between terminals Tc and E1 of DLC 2 or DLC 1.
C
OK
PTurn ignition switch ON.
Measure voltage between terminals TC and E1 of DLC
2 or DLC 1.
Voltage: 10 ± 14 V
Proceed to next circuit inspection shown on problem
symptoms chart (See page BR±160).
2Check for open and short in harness and connector between ABS & TRAC ECU, TRAC\
ECU and
DLC 2 (or DLC 1), DLC 2 (or DLC 1) and body ground (See page IN±33).
Repair or replace harness or connector.
Check and replace TRAC ECU.
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)BR±227
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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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ANTI±LOCK BRAKE SYSTEM (ABS)
BR0EU±04
DESCRIPTION

ABS is a brake system which controls the brake cylinder hydraulic pressure \
to all 4 wheels during sudden
braking and braking on slippery road surfaces, preventing the wheels from locki\
ng. ABS provides the
following benefits:
(1) Enables steering round an obstacle with a greater degree of certai\
nty even when panic braking.
(2) Enables stopping during panic braking while keeping the effect upon stability and steerability to a mini-
mum, even on curves.

In case a malfunction occurs, a diagnosis function and fail±safe system have been adopted for the ABS.
SYSTEM PARTS LOCATION
BR02L±05
BR±52±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)
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BR0EV±04
HYDRAULIC SYSTEM DIAGRAM
w/o TRAC:
±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)BR±53
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w/ TRAC:
BR±54±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)
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BR0EW±05
WIRING DIAGRAM
w/o TRAC:
±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)BR±55
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w/ TRAC:
BR±56±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)
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BR0EX±01
ECU TERMINALS
±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)BR±57
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BR±58±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)
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