brake sensor TOYOTA CAMRY V20 1986 Service Information

AT4675r Non-reusable part70 (61 in.-lb, 6.9)kg-cm (ft-lb, N-m)Neutral Start Switch
55 (48 in.-lb, 5.4)
Manual Shift Leverr Lock Plate Elbow Snap Ring
275 (20, 27)Coverr O-Ring r O-Ring r O-RingPlug 2nd Coast
Brake Pistonr O-Ring Spring r O-Ring
275 (20, 27)
Union (A540E)No. 2 Speed Sensor
(A540E)
r O-Ring
275 (20, 27)
Elbow (A540H) Throttle Cabler GasketTransaxle Case
Upper Cover (A540H) r O-Ring r Gasket
275 (20, 27)
Union (A540H) Transaxle Case
Upper CoverBreather Hose
(A540H)
100 (7, 10) 200 (14, 20)
r O-Ring Solenoid WireBreather Tube (A540H) A540E and A540H
r O-Ring
: Specified torque
REMOVAL OF COMPONENT PARTS
COMPONENTS
- AUTOMATIC TRANSAXLERemoval of Component PartsAT-13

2. Electronic Control System
COMPONENTS
The electronic control system for controlling the shift timing and the operation of the lock±up clutch
is composed of the following three parts:
(a) Sensors: These sense the vehicle speed and throttle position and send this data to the ECT ECU
in the form of electronic signals.
(b) ECT ECU: This determines the shift and lock±up timing based upon the signals from the. sensors.
(e) Actuators: Solenoid valves divert hydraulic pressure from one circuit of the hydraulic control unit
to another, thus controlling shifting and lock±up timing.
VEHICLE SPEED SENSOR
NO. 1 AND NO. 2
BRAKE LIGHT SWITCH
O/D MAIN SWITCH
THROTTLE POSITION
SENSOR
CRUISE CONTROL
COMPUTER PATTERN SELECT
SWITCH
NEUTRAL START
SWITCH
LOCK±UP SOLE±
NOID VALVE NO. 2 SOLENOID
VA LV E NO. 1 SOLENOID
VA LV E
Control of shift
tinning
Self±diagnostic
systemControl of lock±up
timing
WATER TEMP.
SENSORO/D OFF INDI±
CATOR LIGHT Back±up system
ECT ECU
ENGINE
ECU
ACTUATOR
SENSOR ACTUATOR
± AUTOMATIC TRANSAXLEDescription (A140L and A140E)AT±10

Diagnosis System (A140E)
DESCRIPTION
1. A self±diagnosis function is built into the electrical control system.
Warning is indicated by the overdrive OFF indicator.
HINT: Warning and diagnostic codes can be read only when
the overdrive switch is ON. If OFF, the overdrive OFF
indicator is lit continuously and will not blink.
(a) If a malfunction occurs within the speed sensors (No.
1 or 2) or solenoids (No. 1 or 2), the overdrive OFF
light will blink to. warn the driver. .
However, there will be no warning of a malfunction with
lock±up solenoid.
(b) The diagnostic code can be read by the number of blinks of
the overdrive OFF indicator when terminals
Tt and E1 are short±circuited. (See page AT±17)
tc) The throttle position sensor or brake signal are not indi-
cated, but inspection can be made by checking the voltage at
terminal Tt of the check connector (diagnosis).
(d) The signals to each gear can be checked by measuring the
voltage at terminal Tt of the check connector while driving.
2. The diagnostic (malfunction) code is retained in memory by the
CPU and due to back±up voltage, is not canceled out when the
engine is turned off. Consequently, after repair, it is necessary
to turn the ignition switch off and remove the fuse EFI (15A) or
disconnect the ECT computer connector to cancel out the diag-
nostic (malfunction)
code. (See page AT±18)
HINT:
wLow battery voltage will cause faulty operation of the diag-
nosis system. Therefore, always check the battery first.
w Use a voltmeter and ohmmeter that have an impedance
of at least 10 k 11 IV.
CHECK O/D OFF INDICATOR LIGHT
1. Turn the ignition switch ON.
2. The O/D OFF light will come on when the O/D switch is
placed at OFF.
3. When the O/D switch is set to ON, the O/D OFF light
should go out.
If the O/D OFF light flashes when the O/D switch is set
to ON, the electronic control system is faulty.
± AUTOMATIC TRANSAXLETroubleshooting (Diagnosis System) (A140E)AT±16

3. INSPECT EACH UP±SHIFT POSITION
(a) Warm up the engine.
Coolant temperature: 176
°F (80°C)
(b) Turn the O/D switch to ºONº.
(c) Place the pattern select switch in ºNormalº and the shift
lever into the D range.
(d) During a road test (above 10 km/h or 6 mph) check that
voltage at the ECT terminal is as indicated below for
each up±shift position.
If the voltage rises from 0V to 7V in the sequence
shown, the control system is okay.
The chart on the left shows the voltmeter reading and
corresponding gears. .
HINT: Determine the gear position by a light shock or
change in engine rpm when shifting. The lock±up clutch
will turn ON only infrequently during normal 2nd and 3rd
gear operation. To trigger this action, press the acceler-
ator pedal to 50% or more of its stroke. At less than
50%, the voltage may change in the sequence 2V ± 4V
± 6V ± 7V. 2. INSPECT BRAKE SIGNAL
(a) Depress the accelerator pedal until the ECT terminal
indicates 8V.
(b) Depress the brake pedal and check the voltage read-
ing from the ECT terminal.
(c) Brake pedal depressed . . . . . . . . . . 0V
Brake pedal released . . . . . . . . . . . . 8V
If not as indicated, there is a malfunction in either the
stop light switch or circuit.
INSPECTION OF Tt TERMINAL VOLTAGE
1. INSPECT THROTTLE POSITION SENSOR SIGNAL
(a) Turn the ignition switch to ON. Do not start the engine.
(b) Connect a voltmeter to terminals Tt and E1.
(c) While slowly depressing the accelerator pedal,
check that ECT terminal voltage rises in sequence.
if the voltage does not change in proportion to the
throttle opening angle, there is a malfunction in the
throttle position sensor or circuit.
± AUTOMATIC TRANSAXLETroubleshooting (Electronic Control System) (A140E)AT±31

( ) 1: No fail±safe function X: Malfunctions
HINT: (A540H) When any one of the speed sensors (front or rear) or center differential control sole-
noid valves (No. 1 or No. 2) malfunction, the ECT ECU stops center differential control and main-
tains the center differential in a free condition.
Operating Mechanism for Each Gear (A540E A540H)
1. CLUTCH BRAKE AND ONE±WAY CLUTCH
A540E, A540H
Down±shift only ± no up±shift
2. SOLENOID SYSTEM
Possible gear positions in accordance with solenoid operating conditions.
A540E, A540H
NO. 2 SOLENOID
MALFUNCTIONING NO. I SOLENOID
MALFUNCTIONINGBOTH SOLENOIDS
MALFUNCTIONING Shift lever
positionGear position
NORMAL
D rangeParking
2 range
L rangeReverse
Neutral
Range
2nd3 rd
O/D
2nd1st
1st 1st2nd
3rd
± AUTOMATIC TRANSAXLETroubleshooting (Operating Mechanism for Each Gear
(A540E and A540H)AT±189

Diagnosis System
DESCRIPTION
1. A self±diagnosis function is. built into the electrical control
system. Warning is indicated by the overdrive OFF indicator.
HINT: Warning and diagnostic codes can be read only when
the overdrive switch is ON. If OFF, the overdrive OFF
indicator is lit continuously and will not blink.
(a) If a malfunction occurs within the speed sensors or sole-
noids, the overdrive OFF light will blink to warn the driver.
However, there will be no warning of a malfunction with
lock±up solenoid.
W The diagnostic code can be read by the number of
blinks of the overdrive OFF indicator when terminals
Tt and E1 are short±circuited. (See page AT± 191)
(c) The throttle position sensor or brake signal are not indicated,
but inspection can be made by checking the voltage at ter-
minal Tt of the check connector.
(d) The signals to each gear can be checked by measuring the
voltage at terminal Tt of the check connector while driving.
2. The diagnostic (malfunction) code is retained in memory by the
ECU and due to back±up voltage, is not canceled out when the
engine is turned off. Consequently, after repair, it is necessary
to turn the ignition switch off and remove the fuse EFI (15A)
(A540E) or DOME (20A)
(A540H) or disconnect the Engine and ECT ECU (A540E)
or ECT ECU (A540H) connector to cancel out the diagnostic
(malfunction) code. (See page AT±192)
HINT:
wLow battery voltage will cause faulty operation of the diag-
nosis system. Therefore, always check the battery first.
wUse a voltmeter and ohmmeter that have an impedance of
at least 10 k
/V.
CHECK O/D OFF INDICATOR LIGHT
1. Turn the ignition switch ON.
2. The O/D OFF light will come on when the O/D switch
placed at OFF.
3. When the O/D switch is set to ON, the O/D OFF light should go
out.
If the O/D OFF light flashes when the O/D switch is set to
ON, the electronic control system is faulty.
± AUTOMATIC TRANSAXLETroubleshooting (Diagnosis System) (A540E and A540H)AT±190

Is voltage between ECT ECU terminals BK
and GND as follows? .
0V: Brake pedal released
10 ± 14V: Brake pedal depressed
Check voltage between ECT ECU terminals
P and GND.
Power pattern: 10 ~ 14V
Normal pattern: 1 V Warm up engine
Coolant temp.: 176°F (80°C)
ATF temp.: 122 ± 176°F (50 ± 80°C)
Connect a voltmeter to terminals Tt and E1.
Does Tt terminal voltage vary with changes in
throttle opening? (Seepage AT±21 5)
ECU power source and ground faulty
Throttle position signal faulty
Tt terminal wire open or short
Faulty pattern select switch system
Shift point too high or too low
Faulty ECT ECU
Faulty speed sensorBrake signal
faulty
Trouble No. 2
Ye s
Ye s
± AUTOMATIC TRANSAXLETroubleshooting (Electronic Control System) (A540E and
A540H)AT±212

3. INSPECT EACH UP±SHIFT POSITION
(a) Warm up the engine.
Coolant temperature: 176
°F (80°)
(b) Turn the O/D switch to ºONº.
(c) Place the pattern select switch in ºNormalº and the shift
lever into the D range.
(d) During a road test (above 10 km/h or 6 mph) check that volt-
age at the Tt terminal is as indicated below for each up±
shift position.
If the voltage rises from 0V to 7V in the sequence shown,
the control system is okay.
The chart on the left shows the voltmeter reading and cor-
responding gears.
HINT: Determine the gear position by a fight shock or
change in engine rpm when shifting. The lock±up clutch will
turn ON only infrequently during normal 2nd and 3rd gear
operation. To trigger this action, press the accelerator pedal
to 50% or more of its stroke. At less than 50%, the voltage
may change in the sequence 2v ± 4V ± 6V ± 7V. 2. INSPECT BRAKE SIGNAL
(a) Depress the accelerator pedal until the Tt terminal indi-
cates 8V.
(b) Depress the brake pedal and check the voltage read-
ing from the Tt terminal.
Brake pedal depressed ...... 0V
Brake pedal released . . . . . . . . 8V
If not as indicated, there is a malfunction in either the
stop light switch or circuit.
INSPECTION OF ECT OR Tt TERMINAL
VOLTAGE
1. INSPECT THROTTLE POSITION SENSOR SIGNAL
(a) Turn the ignition switch to ON. Do not start the engine.
(b) Connect a voltmeter to terminals Tt and E1.
(c)while slowly depressing the accelerator pedal, check
that Tt terminal voltage rises in sequence.
If the voltage does not change in proportion to the
throttle opening angle, there is a malfunction in the
throttle position sensor or circuit.
± AUTOMATIC TRANSAXLETroubleshooting (Electronic Control System) (A540E and
A540H)AT±215

Taillight Failure Sensor
INSPECTION OF SENSOR
1. INSPECT WARNING LIGHT OPERATION
(a) Disconnect the connector from the failure sensor and
ground the terminal 3 on the wire harness side.
(b) Remove the CHARGE fuse and turn the ignition
switch ON, check that the bulb lights.
If bulb does not light, inspect the bulb.
2. INSPECT SENSOR CIRCUIT
Disconnect the failure sensor connector and inspect the
connector on the wire harness side as shown in the chart.
If circuit is as specified, replace the relay.
Stop light switch ON (Brake pedal depressed)Stop light switch OFF (Brake pedal released)
Turn light control switch TAIL or HEAD Turn ignition switch to OFF or ACC Turn ignition switch to OFF or ACC
Turn light control switch OFF Turn ignition switch ON
Remove CHARGE fuse
Turn ignition
switch ON
Install CHARGE fuse
Tester
connectionSpecified value
Battery voltage
Battery voltage
Battery voltageBattery voltage
No voltage Continuity
No voltageContinuityNo vottage No voltage Continuity
ContinuityNo voltage
Continuity ContinuityConditionCheck for
Voltage Voltage
VoltageAlways
AlwaysAlways
± BODY ELECTRICAL SYSTEMLightingBE±20

Light Control Rheostat
TAIL Fuse
IGN Fuse
Water Temperature Sender Gauge
Ground
Seat Beh Warning Relay
Brake Fluid Level Warning Switch and Parking
Brake Switch
CHARGE Fuse
TCCS ECU
A.B.S. ECU
Cruise Control ECU and ECT ECU
Ground
Fuel Sender Gauge Terminal 3
Fuel Sender Gauge Terminal 2
GAUGE Fuse
DOME Fuse
Door Courtesy Switch
Low Oil Pressure Switch
Light Failure Sensor
Combination Meter and Gauges
(w/o Tachometer)
Turn Signal Switch Terminal 28
Ground
Turn Signal Switch Terminal 25
Turn Signal Switch Terminal 23 (USA)
HEAD±HI (RH) Fuse (CANADA)
A/T Oil Temperature Switch
COMBINATION METER CIRCUIT
Wiring Connector Side
No.
± BODY ELECTRICAL SYSTEMCombination MeterBE±32