TOYOTA CAMRY V20 1986 Service Information

Electronic Control System (A140E)
ELECTRONIC CONTROL CIRCUIT
± AUTOMATIC TRANSAXLETroubleshooting (Electronic Control System) (A140E)AT±24

ELECTRONIC CONTROL COMPONENTS
± AUTOMATIC TRANSAXLE± Troubleshooting (Electronic Control System) (A140E)AT±25

Disconnect ECT ECU connector and road test.
Does the transaxle operate i n the respective gear
when in the following ranges while driving?
D range . . Overdrive
2 range . . 3 rd gear
L range . . . 1 st gear
TROUBLESHOOTING FLOW±CHART
Trouble No.1 No Shifting
Connect a voltmeter to the check connector termi-
nals Tt and E1.
Does ECT terminal voltage vary with changes in
throttle opening?
Is voltage between ECT ECU terminals
BK and GND as follows?
0V: Brake pedal released
10 ± 14 V: Brake pedal depressed Warm up engine
Coolant temp.: 17f6°F (80°C)
ATF temp.: 122 ± 176°F (50 ± 80°C)
wECU power source and ground faulty
wThrottle position signal faulty
wECT terminal wire open or short
Ye s
Continued on page AT±27Brake signal
faulty
Transaxle faulty Ye s
Ye s
± AUTOMATIC TRANSAXLETroubleshooting (Electronic Control System) (A±1 40E)AT±26

Connect ECT ECU connector and road test.
Does ECT terminal voltage rise from 0V
to 7V in sequence?
Are there battery voltage between
ECT ECU terminals 2 ± GND
when in the D range?
Are there battery voltage between ECT ECU
terminals L ± GND when in the D range?
Neutral start switch circuit faulty
Neutral start switch faultyProceed to trouble 3
(See page AT±29) Continued from page AT±26
Transaxle faulty
Solenoid faulty
Try another ECT ECU.0
7V
0
3V0
5V
Ye sYe s
± AUTOMATIC TRANSAXLETroubleshooting (Electronic Control System) (A140E)AT±27

Connect a voltmeter to the check connector
terminals Tt and El.
Does ECT terminal voltage vary with changes in throttle
opening?
Check voltage between ECT ECU terminals
PWR and GND.
Power pattern: 10 ± 14V
Normal pattern: 1VIs voltage between ECT ECU terminals
BK and GND as follows?Tt
0V: Brake pedal released
10 ± 14V: Brake pedal depressed Warm up engine
Coolant temp.: 176°F (80°C)
ATF temp.: 122 ± 176°F (50 ± 80°C)
wECU power source and ground faulty
wThrottle position signal faulty
wECT terminal wire open or short
Faulty pattern select switch system
Shift point too high or too low
wFaulty ECT ECU
w|Faulty transaxle
Trouble No. 2
Brake sig-
nal faulty Ye s
Ye s
± AUTOMATIC TRANSAXLETroubleshooting (Electronic Control System) (A140E)AT±28

Is voltage between terminals OD2 and GND as fol-
lows?
O/D switch turn ON: 10 ± 14V
O/D switch turn OFF: 0VRoad test while shifting manually with ECT
ECU connector disconnected.
Is there overdrive up±shift in the D range when
shifting from L to 2 to D?
Is voltage between terminals OD, and GND as fol-
lows?
Approx. 5 V
Is voltage between ECT ECU terminals
OD, and GND normal with the cruise control com-
puter connector pulled out?Connect ECT ECU connector, and while driving
does ECT terminal voltage rise from
0V to 7V in sequence?
No up±shift to overdrive (After warm±up)
Are there battery voltage between
ECT ECU terminals L and GND
when in the D range?Are there battery voltage between
ECT ECU terminals 2 and
GND when in the D range?
wFaulty neutral start switch circuit
wFaulty neutral start switch
Faulty ECT ECU
Faulty cruise control wire harnessFaulty O/D switch harness
Faulty O/D switch
Faulty cruise control computer±Faulty transaxle
Faulty solenoid
Try another ECT ECU
Try another ECT ECUFaulty transaxle
Trouble No. 3
Ye sYe s
Ye s
Ye sYe sYe s
± AUTOMATIC TRANSAXLETroubleshooting (Electronic Control System) (A140E)AT±29

Road test
Connect a voltmeter to the check connector
terminals Tt and El.
Is there 7, 5 or 3 V in the lock±up range while driving?
Is voltage between ECT ECU Terminals
BK and GND as follows?
Brake pedal depressed: 10 ± 14V
Brake pedal released: 0V Warm up engine ,
Coolant temp.: 176°F (80°C)
ATF temp.: 122 ± 176°F (50 ± 80°C)
wLock±up solenoid stuck
wFaulty transmission
wFaulty lock±up mechanism
wFaulty ECU power source and ground
w Faulty throttle position signal
No lock±up (After warm±up)
Faulty brake signal Trouble No. 4
Ye s
Ye s
± AUTOMATIC TRANSAXLETroubleshooting (Electronic Control System) (A140E)AT±30

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

INSPECTION ELECTRONIC CONTROL
COMPONENTS
1. INSPECT VOLTAGE OF ECT ECU CONNECTOR
(a) Remove the glove box and instrument panel.
(b) Turn on the ignition switch.
(e) Measure the voltage at each terminal.
Throttle valve fully closed to fully open Throttle valve fully closed to fully open
Throttle valve fully closed to fully open
Vehicle moving (Cruise control OFF)Standing still (Cruise control OFF) Throttle valve opening above 1 .5°
When brake pedal is not depressed When brake pedal is depressed Throttle valve fully closed Throttle valve fully closed
Throttle valve fully closed
Throttle valve fully closed Throttle valve fully open Throttle valve fully open Throttle valve fully openMeasuring condition
Except L range
Except N range Except 2 rangeVoltage (V)
Terminal
N range 2 range
L range
± AUTOMATIC TRANSAXLETroubleshooting (Electronic Control System) (A140E)AT±32

2. INSPECT SOLENOID
(a) Disconnect the connector from the ECT computer.
(b) Measure the resistance between S1, S2, SL and
ground.
Resistance: 11 ± 15


(c) Apply battery voltage to the solenoid. Check that an
operation noise can be heard from the solenoid.
HINT: If there is foreign matter in the solenoid valve,
there will be no fluid control even with solenoid opera-
tion.
3. CHECK SOLENOID SEALS
If there is foreign material in the solenoid valve, there
will be no fluid control even with solenoid operation.
(a) Check No. 1 and No. 2 solenoid valves.
wApplying 5 kg/cm2 (71 psi, 490 kPa) or compressed
air, check that the solenoid valves do not leak the air.
wWhen supply battery voltage to the solenoids,
check that the solenoid valves open.
(b) Check the lock±up solenoid valve.
wApplying 5 kglcm2 (71 psi, 490 kPa) of com-
pressed air, check that the solenoid valve
opens.
wWhen supply battery voltage to the solenoid,
check that the solenoid valve does not leak the
air.
Coolant temp. above 122°F (50°C) Coolant temp. below 122°F (50°C)
O/D main switch turned OFF O/D main switch turned ONMeasuring condition
Ignition switch ON
Vehicle movingStanding still
PWR pattern
NORM patternVoltage (V)
Terminal
± AUTOMATIC TRANSAXLETroubleshooting (Electronic Control System) (A140E)AT±33