sensor TOYOTA CAMRY V20 1986 Service Information

ANTI±LOCK BRAKE SYSTEM (A.B.S.)
Description
wThe A.B.S. is a brake system which controls the wheel cylinder hydraulic pressure of all four wheels during
sudden braking and braking on slippery road surfaces, preventing the wheels from locking. This A.B.S.
provides the following benefits:
(1) Enables steering round an obstacle with a greater degree of certainty even when panic braking.
(2) Enables stopping in a panic brake while keeping the effect upon stability and steerability to a mini-
mum, even on curves.
wThe function of the A.B.S. is to help maintain directional stability and vehicle steerability on most road
conditions. However, the system cannot prevent the vehicle from skidding if the cornering speed limit is
exceeded.
wThe A.B.S. has a longitudinal deceleration sensor to match braking characteristics to the full±time four±
wheel drive. (For 4WD)
wIn case a malfunction occurs, a diagnosis function and fail±safe system have been adopted for the A.B.S.
to increase serviceability.
2WD (SEDAN)
± BRAKE SYSTEMAnti±lock Brake System (A.B.S.)BR±56

From the wheel speed signals from each sensor, it calculates
acceleration, deceleration and slip values and sends signals to
the actuator to control brake fluid pressure. Detects the deceleration speed of the vehicle and sends a signal'
accordingly to the A.6.S. computer.
Controls the brake fluid pressure to each disc brake cylinder
through signals from the computer. Lights up to alert the driver when trouble has occured in the
Anti±lock Brake System. Detects the wheel speed of each of the left and right front
wheels.
Detects the wheel speed of each of the left and right rear wheels.
LOCATION OF SYSTEM PARTS FUNCTION OF COMPONENTS
Anti±lock Brake System Computer Deceleration Sensor (For 4WD)
ANTI LOCK Warning Light Front Speed Sensor
Rear Speed SensorComponentFunction
Actuator
WAGON
± BRAKE SYSTEMAnti±lock Brake System (A.B.S.)BR±58

Brake Actuator
CONNECTOR A
Anti±lock Brake System Computer
CONNECTORS (2WD)
Front Speed Sensor (LH)Front Speed Sensor (RH)
Rear Speed Sensor (R H
) Rear Speed Sensor ( LH
) Check ConnectorCONNECTOR C
CONNECTOR B
± BRAKE SYSTEMAnti±lock Brake System (A.B.S.)BR±65

Anti±lock Brake System ComputerBrake Actuator
CONNECTOR A
CONNETORS (4WD)
Front Speed Sensor (LN)
Front Speed Sensor (RH)
Rear Speed Sensor (RH) Rear Speed Sensor (LH)
Deceleration Sensor Check Connector
CONNECTOR B
CONNECTOR C
Ts Connector
± BRAKE SYSTEMAnti±lock Brake System (A.B.S.)BR±66

Deceleration sensor
Deceleration sensor installation
Wire harness and connector of
deceleration sensor
Pump motor of actuator locked or open circuit in pump motor
circuit in actuatorActuator inside wire harness
Pump motor relay
Wire harness and connector
of pump motor relay circuit Actuator inside wire harness
Solenoid relay
Wire harness and connector of solenoid
relay circuit
Speed sensor
Sensor rotor
Wire harness and connector of
speed sensor
Pump motor, relay and battery
Wire harness, connector and ground
bolt or actuator pump motor circuit Open or short circuit in 3 position solenoid of front right wheel
Actuator solenoid
Wire harness and connector of
actuator solenoid circuit Open or short circuit in 3 position solenoid of rear right wheel Open or short circuit in 3 position solenoid of front left wheel
Open or short circuit in 3 position solenoid of rear left wheel
Open circuit in front left or rear right wheel speed sensor
Open circuit in front right or rear left wheel speed
sensorRear right wheel speed sensor signal malfunction
Abnormally high battery voltage 0 6.2 V or higher) Front right wheel speed sensor signal malfunction
Front left wheel speed sensor signal malfunction
Rear left wheel speed sensor signal malfunction
Open or short circuit in deceleration sensor Short circuit in pump motor relay circuit Open circuit in pump motor relay circuit
Low battery voltage (9.5 V or lower) Open circuit in solenoid relay circuit
Short circuit in solenoid relay circuit
DIAGNOSTIC CODE
Battery
Voltage regulator
Malfunction in deceleration sensorWrong both rear axle hubs
Malfunction in computerRear sensor rotors
Computer Light Pattern
Trouble Part Diagnosi
s Code No.
± BRAKE SYSTEMlock Brake System (A.B.S.)BR±69

wCheck connector is disconnected.
wOpen circuit in wire harness between computer terminal T and actuator terminal T.
wActuator terminal GND is improperly connected or open circuit in wire harness between actuator
terminal GND and body ground.
wConnect circuit in wire harness between computer terminal Ts and Ts connector. (For 4WD)
wBrakes pull.
wBraking inefficient.
wA.B.S. operates at ordinary braking.
wA.B.S. operates just before stopping at ordinary braking.
wBrake pedal pulsates abnormally while A.B.S. working.
Disconnect connector from computer, inspect
continuity between each speed sensor termi-
nals on wire harness side.
(See page BR±103) Are each speed sensors installed in place?
And are each installation bolts tightened se-
curely?Does warning light show the diagnostic
normal code? (Ignition switch on)ºANTILOCKº warning light comes on and off.
Disconnect check connector.
(See page BR±68)
See diagnostic code.
(See page BR±69)
Speed sensor installation faulty.
Continued on page BR±75 YES
YES
± BRAKE SYSTEMAnti±lock Brake System (A.B.S.)BR±74

(For 4WD)
Try deceleration sensor operation diagno-
sis system.
Is sensor operation OK?
(See page BR±82) Does any abnormal change occur in continuity
when the connectors or wire harness of the
speed sensor and intermediate connectors are
twisted or bent?
Try speed sensor diagnosis system.
Is sensor signal level OK?
(See page BR±70)
Try speed sensor diagnosis system.
Is sensor signal change OK?
(See page BR±70) Is there foreign material or ferric chips on the
sensor tip?
Inspect speed sensor, and replace if
necessary.
Inspect sensor rotor, and replace if
necessary.
Inspect the actuator operation.
(See page BR±84)Faulty deceleration sensor or
sensor installation faulty.Clean chips from the speed sensor. YES
(Abnormal
change)
Is actuator operation OK?Continued on page BR±74
Faulty wire harness.
Faulty computer.
NO
(No change)
Faulty actuator. YES
YES YES
YESYES
± BRAKE SYSTEMAnti±lock Brake System (A.B.S.)BR±75

Speed Sensor Diagnosis System
PRECAUTION
While checking the speed sensor diagnosis system,
A.B.S. does not work and brake system works as normal
brake system.
INSPECTION OF DIAGNOSIS SYSTEM
1. INSPECT BATTERY VOLTAGE
Inspect that the battery voltage is about 12 V.
2. CHECK THAT WARNING LIGHT TURNS ON
(a) Turn the ignition switch on.
(b) Check that the ºANTILOCKº warning light turns on for
3 seconds.
If not, inspect and repair or replace the fuse, bulb and wire
harness.
(c) Check that the ºANTILOCKº warning light turns off.
(d) Turn the ignition switch off.
3. PERFORM FOLLOWING STEPS
(2WD)
(a) Disconnect the check connector from the actuator.
(b) Pull the parking brake lever up, and start the engine.
(d) Check that the warning light blinks about 4 times ev-
ery 1 second as shown. (c) Depress the brake pedal 4 to 6 times within 2
seconds.
± BRAKE SYSTEMAnti±lock Brake System (A.B.S.)BR±77

4. INSPECT SENSOR SIGNAL LEVEL
Drive the vehicle straight ahead at about 4 ±6 km/h (2.5
± 3.7 mph), and check that the warning light turns on after
a 1 second pause.
If the warning light turns on without blinking when the ve-
hicle speed is not within the specified speed range above,
stop the vehicle and read the diagnostic code, and repair
the malfunctioning parts.
(See step S on page BR±79)
HINT: If the warning light turns on while the vehicle speed
is within specified speed range above, the check is com-
pleted. And when the vehicle speed exceeds 6 km/h
(3.7mph), the warning light will blink again. In this condi-
tion, speed sensors are OK.
NOTICE: While the warning light is off, do not give any
shocks to vehicle such as acceleration, deceleration, brak-
ing, shift change, steering or shocks from the road condi-
tion.
(4WD)
(a) Remove the rubber cap from the Ts connector lo-
cated in front of the actuator.
(b) Connect the terminals of Ts connector.
(c) Pull the parking brake lever up, and start the engine.
NOTICE: Do not depress the brake pedal.
(d) Check that the warning light blinks about 4 times ev-
ery 1 second as shown.
± BRAKE SYSTEMAnti±lock Brake System (A.B.S.)BR±78

5. INSPECT SENSOR SIGNAL CHANGE
Drive the vehicle straight ahead at about 45 ± 55 krn/h
(28.0 ± 34.2 mph), and check that the warning light turns
on after a 1 second pause.
If the warning light turns on without blinking when the ve-
hicle speed is not within the specified speed range above,
stop the vehicle and read the diagnostic code, and repair
the malfunctioning .parts.
(See step 6 on this page)
HINT: If the warning light turns on while the vehicle speed
is within specified speed range above, the check is com-
pleted. And when the vehicle speed is not within specified
speed range, the warning light will blink again. In this con-
dition, sensor rotors are OK.
NOTICE: While the warning light is off, do not give any
shocks to vehicle such as acceleration, deceleration, brak-
ing, shift change, steering or shocks from the road condi-
tion.
HINT: The first number of blinks will equal the first digit
of a two digit diagnostic code. After a 1.5 second pause,
the 2nd number of blinks will equal the 2nd number of a
two digit code. If there are two or more codes, there will
be a 2.5 second pause between each code, and then
indication will begin again after a 4.0 second pause,
continuing in order from the smaller value up to the larg-
er one. 6. READ DIAGNOSTIC CODE
Stop the vehicle and disconnect the check connector, and
warning light will begin to blink. Read the number of
blinks.
(See DIAGNOSTIC CODE on page BR±81)
7. REPAIR MALFUNCTIONING PARTS
Repair or replace the malfunctioning parts.
HINT: When repairing or replacing parts, turn the ignition
switch OFF.
± BRAKE SYSTEMAnti±lock Brake System (A.B.S.)BR±79