1986 TOYOTA CAMRY V20 battery

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

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

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

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

CANCEL OUT DIAGNOSTIC CODE
1. After repair of the trouble area, the diagnostic code
retained in memory by the Engine and ECT ECU (A540E)
or ECT ECU (A540H) must be canceled by removing the fuse EFI
(15A) (A540E) or DOME (20A) (A540H) for 10
seconds or more, depending on ambient temperature (the
lower the temperature, the longer the fuse must be left
out with the ignition switch OFF.
wHINT:Cancellation can be also done by removing the battery
negative (±) terminal, but in this case other memory systems
(engine control system diagnosis memory,
clock. ETR, etc.) will also be canceled out
wThe diagnostic code can be also canceled out by disconnect-
ing the Engine and ECT ECU (A540E) or ECT
ECU (A540H) connector.
wIf the diagnostic code is not canceled out, it will be retained
by the Engine and ECT ECU (A540E) or ECT
ECU (A540H) and appear along with a new code in
event of future trouble.
2. After cancellation, perform a road test to confirm that a
ºnormal codeº is now read on the O/D OFF indicator.
± AUTOMATIC TRANSAXLETroubleshooting (Diagnosis System) (A540E and A540H)AT±193

MEASURE CENTER DIFFERENTIAL CONTROL PRESSURE (A540H Only)
(a) Warm up the transaxle fluid (122 ± 176°F or 50 ± 80°C)
(b) Measure the line pressure. (See page AT±224)
(e) Remove the transfer case test plug and mount the oil pressure gauge (SST).
SST 09992±00094
(d) Check the parking brake to see that it is fully applied chock the four wheels.
(e) Disconnect the connector from ECT ECU.
(f) Start the engine.
(g) Apply battery voltage to terminal SD1, or SD2 of the wire harness side connector and turn the No. .1
and No. 2 center differential control solenoid valves to either ON or OFF.
(h) Shift into the L range, step down strongly on the brake pedal with your left foot and while manipulating the
accelerator pedal with the right foot, measure the pressure at the engine speeds specified in the table.
kg/cm2 (psi, kPa)
HINT: After inspecting the center differential control pressure, erase the diagnosis codes (No. 73 and 74)
from the memory.
Condition of
Solenoid
ValvesNo. 1 Solenoid
Valve
No. 2 Solenoid
Valve
Engine
RPML range
Range
Idling
Stall
± AUTOMATIC TRANSAXLETroubleshooting (Mechanical System Tests) (A540E and
A540H)AT±226

3. (A540E)
INSPECT SOLENOID VALVES
(a) Disconnect the connector from Engine and ECT ECU
(b) Measure the resistance between S1, S2, SL and
body ground.
Resistance: 11 ± 15


(e) Apply battery voltage to each terminal.
Check that an operation noise can be heard from
the solenoid.
Center differential control switch AUTO position
Center differential control switch AUTO position Center differential control switch turned OFF
Center differential control switch turned OFF Coolant temp. below 122°F950°0 Throttle valve fully closed to fully open
Coolant temp. above 122°F (50°C0 O/D main switch turned OFF O/D main switch turned ON
Brake pedal is depressed
Brake pedal is releasedMeasuring condition
Except 2 range
Except N range Except P range
Except L range
NORM patternVoltage (V)
PWR pattern Terminal
N range2 range P range
L range
± AUTOMATIC TRANSAXLETroubleshooting (Electronic Control System) (A540E and
A540H)AT±218

5. (A540H)
INSPECT CENTER DIFFERENTIAL CONTROL
SOLENOID VALVES
(a) Disconnect the connector from ECT ECU.
(b) Measure the resistance between SD1, SD2 and body ground.
Resistance: 11 ± 15


(c) Apply battery voltage to each terminal.
Check that an operation noise can be heard from± the sole-
noid.
6. 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. (A540E,
A540H)
wApplying 5 kg/cm2 (71 psi, 490 kPa) of compressed air,
check that the solenoid valves open 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. (A540E, A540H)
wApplying 5 kglcm2 (71 psi, 490 kPa) of compressed air, check
that the solenoid valve opens.
wWhen supply battery voltage to the solenoid, check that the
solenoid valve does not leak the air. 4. (A540H)
INSPECT SOLENOID VALVES
(a) Disconnect the connector from ECT ECU.
(b) Measure the resistance between S1, S2, SL and body
ground.
Resistance: 11 ± 15


(c) Apply battery voltage to each terminal.
Check that an operation noise can be heard from the
solenoid.
(c) Check No. 1 and No. 2 center differential control
solenoid valves. (A540H)
wApplying 5 kg/cm2 (71 psi, 490 kPa) of com-
pressed air, check that the solenoid valves
open do not leak the air.
wWhen supply battery voltage to the solenoids,
check that the solenoid valves open.
± AUTOMATIC TRANSAXLETroubleshooting (Electronic Control System) (A540E and
A540H)AT±219