1986 TOYOTA CAMRY V20 ECU

IN0036
Seal Lock Adhesive
GENERAL REPAIR INSTRUCTIONS
1. Use fender, seat and floor covers to keep the vehicle
clean and prevent damage.
2. During disassembly, keep parts in order to facilitate
reassembly.
3. Observe the following:
(a) Before performing electrical work, disconnect the
negative cable four the battery terminal.
(b) If it is necessary to disconnect the battery for in-
spection or repair, always disconnect the cable from
the negative (-) terminal which is grounded to the
vehicle body.
(c) To prevent damage to the battery terminal post,
loosen the terminal nut and raise the cable straight
up without twisting it or prying it.
(d) Clean the battery terminal posts and cable termi-
nals with a shop rag. Do not scrape them with a file
or other abrasive object.
(e) Install the cable terminal to the battery post with the
nut loose, and tighten the nut after installation. Do
not use a hammer or such to tap the terminal onto
the post.
(f) Be sure the cover for the positive (+) terminals are
properly in place.
4. Check hoses and wiring connectors to make sure
that they are secure and correct.
5. Non-reusable parts
(a) Always replace cotter pins, gaskets, O-rings and oil
seals etc. with new ones.
(b) Non-reusable parts are indicated in the component
illustrations by the ºrº symbol.
6. Precoated parts
Precoated parts are the bolts and nuts, which have
been coated with a seal lock adhesive at the factory.
(a) If a precoated part is retightened, loosened or
caused to move in any way, it must be recoated
with the specified adhesive.
(b) Recoating of precoated parts
(1) Clean off the old adhesive from the bolt, nut
or installation part threads.
(2) Dry with compressed air.
(3) Apply the specified seal lock adhesive to the
bolt or nut threads.
(c) Precoated parts are indicated in the component il-
lustrations by the º
º symbol.
IN-4- INTRODUCTIONGeneral Repair Instructions

AT5032
(A540H)
The A540H automatic transaxle design is based on the A540E automatic transaxle and equipped with a
center differential and transfer.
This transaxle has the same hydraulic multiplate clutch in the center differential limiting control mecha-
nism as the A241H automatic transaxle on the Corolla All-Trac/4WD Station Wagon. The fluid pressure
acting on the hydraulic multiplate clutch of the A540H is controlled by the ECT ECU (Electronic Control
Unit) according to the vehicle driving conditions. As a result, torque is distributed to the front and rear
wheels appropriately at all times to maximize the overall performance of the 4WD vehicle.
NOTICE: Special handling methods are necessary for full-time 4WD vehicles during inspection and
maintenance. Instructions concerning these handling methods are given on Camry Repair Manual
(Pub. No. RM199U) on page IN-8.
Hydraulic Multiplate ClutchTransfer Front DifferentialCenter
Differential 4-Speed Planetary Gear
Unit and Hydraulic
Control SystemNo. 1 and No. 2 Center Differential
Control Solenoid ValveCenter Differential ControlECT
ECU No. 1 and No. 2 Shift Control
Solenoid Valves and Lock-up
Control solenoid ValveEngine ECU
Throttle Position
Sensor
Stop Light Switch
Vehicle Speed
Sensors
Mode Select Switch
Neutral Start Switch
O/D Main Switch
Center Deff. Control
Switch Shift Control Sectional View
Sensors
- AUTOMATIC TRANSAXLEDescriptionAT-3

VALVE BODY
Hydraulic Control System

A540E, A540H
The hydraulic control system is composed of the oil pump, the valve body, the solenoid valves, the accu-
mulators, the clutches and brakes, and the governor valve as well as the fluid passages which connect all
of these components.
Based on the hydraulic pressure created by the oil pump, the hydraulic control system governs the hy-
draulic pressure acting on the torque converter, clutches and brakes in accordance with the vehicle driving
conditions.
There are three solenoid valves on the valve body.
The No. 1 and No. 2 solenoid valves are turned on and off by signals from ECU to operate the shift valves
and change the gear shift position.
The No. 3 solenoid valve is operated by signals from the ECU to engage or disengage the lock-up clutch
of the torque converter.

A540H
There are two center differential control solenoid valves on the transfer.
The solenoid valves are adjusting the center differential control pressure.
HYDRAULIC CONTROL SYSTEM
Hydr. pressure control
OIL PUMP
CLUTCHES & BRAKESFluid passage switchingPlanetary gear unit
Torque converter
Throttle Cable
SOLENOID VALVES
ECU
AT-8- AUTOMATIC TRANSAXLEOperation

AT3490 AT3491
No. 1 GasketNo. 2 Gasket
AT3474 AT3489
No. 2
Gasket
No. 1 Plate
No. 1
Gasket
(Assembly of Valve Body)
(See page AT-85)
1. POSITION NO. 1 PLATE AND NEW GASKETS ON
UPPER VALVE BODY
Position new No. 1 gasket, No. 1 plate and then new
No. 2 gasket on the upper valve body.
HINT: Since No. 1 gasket and No. 2 gasket are similar,
use the illustration below to discriminate between them.
2. PLACE UPPER VALVE BODY WITH NO. 1 PLATE
AND GASKETS ON LOWER VALVE BODY
Hold the upper valve body, No. 1 plate and gaskets
securely so they do not separate.
Align each bolt hole in the valve bodies with the
gaskets and plate.
AT3475
3. INSTALL AND FINGER TIGHTEN BOLTS IN UPPER
VALVE BODY TO SECURE LOWER VALVE BODY
Install and finger tighten the three bolts.
HINT: Each bolt length (mm, in.) is indicated in the
figure.
- AUTOMATIC TRANSAXLEComponent Parts (Valve Body)AT-95

A140E Automatic Transaxle (ECT)
WHAT IS THE ECT?
ECT means Electronic Controlled Transaxle. The hydraulic control system of the previous automatic
transaxle has been changed, the throttle and governor pressure have been replaced by electronic
signals and a micro computer has been used to give precise control of shift timing and lock±up tim-
ing.
FEATURES OF THE ECT
(a) The shift pattern can be chosen.
In the ECT ECU micro computer used in the A140E, two types of shift pattern, Power and Normal,
are recorded in the memory. By operating the pattern select switch, the driver can select the pre-
ferred shift pattern.
(b) Reduced fuel consumption and reduced shock during shifting is made possible.
Precise control of the shift timing by the ECT ECU, operation of the lock±up clutch from low speeds,
and decreased fuel consumption are made possible. Also, shock during Shifting is reduced.
(e) Self±Diagnostic System
When a malfunction occurs in the electronic control system, the driver is informed of this fact. Also,
there is a Self±Diagnostic System which displays the location of the malfunction when the service
connector is shorted.
(d) Fail±Safe System
A fail±Safe System is included so that, even if a malfunction occurs in the electronic control system,
the vehicle will be able to operate.
CONSTRUCTION AND OPERATION
When the A140E (ECT) is compared with the A140L, the automatic transaxle body has the same
construction and operation, with the exception of the hydraulic control system, as the A140L.
The electronic control system, which controls the shift timing and lock±up timing, has been added.
1. Hydraulic Control System (Comparison with the A140L)
VALVE BODY ± Additions or changes to solenoid valve
In the A140E there are three solenoid valves, the No. 1, the No. 2 and the lock±up solenoid valves.
Shifting occurs according to whether the No. 1 and No. 2 solenoid valves are ON or OFF, and the
lock±up solenoid valve controls the lock±up clutch.
GOVERNOR VALVE ± Removed
With the A140E, the governor valve has been replaced with a speed sensor, so that instead of the
governor pressure, a speed sensor signal is sent to the ECT ECU.
SHIFT CONTROL IN ECT
1. The vehicle speed is sensed by the vehicle speed
sensor, which sends this data to the
ECU in the form of electrical signals.
2. The angle to which the throttle is open is sensed
by the throttle position sensor, which sends this
data to the ECU in the form of electrical signals.
3. The ECT computer determines the shift point on
the basis of these two signals and operates the
solenoid valves in the hydraulic control unit, thus
shifting the transmission.
± AUTOMATIC TRANSAXLEDescription (A140L and A140E)AT±9

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

CANCEL OUT DIAGNOSTIC CODE
1. After repair of the trouble area, the diagnostic code
retained in memory by the ECT ECU must be canceled by
removing the fuse EFI (15A) for 10 seconds or more, de-
pending on ambient temperature (the lower the tempera-
ture, the longer the fuse must be left out) with the ignition
switch OFF.
HINT:
wCancellation can be also done by removing the battery
negative (±) terminal, but in this case other memory sys-
tems (TCCS diagnosis memory, etc.) will be also can-
celed out.
wThe diagnostic code can be also canceled out by discon-
necting the ECT ECU connector.
wIf the diagnostic code is not canceled out, it will be
retained by the ECT ECU 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. HINT: If codes 62, 63 or 64 appear, there is an
electrical malfunction in the solenoid.
Causes due to ±mechanical failure, such as a
stuck valve, will not appear.
Defective No. 1 speed sensor (in combination meter) ±
severed wire harness or short circuit
Severed lock±up solenoid or short circuit ±
severed wire harness or short circuit Defective No. 2 speed sensor (in ATM) ±
severed wire harness or short circuit
Severed No. 2 solenoid or short circuit ±
severed wire harness or short circuitSevered No. 1 solenoid or short circuit ±
severed wire harness or short circuit
DIAGNOSTIC CODES
Diagnosis System
Light Pattern Code No.
Normal
± AUTOMATIC TRANSAXLETroubleshooting (Diagnosis System) (A140E)AT±18

TROUBLESHOOTING FLOW±CHART
HINT:
wIf diagnostic code Nos. 42, 61, 62 or 63 are output, the overdrive OFF indicator light will begin to
blink immediately to warn the driver. However, an impact or shock may cause the blinking to stop;
but the code will still be retained in the ECT ECU memory until canceled out.
wThere is no warning for diagnostic code No. 64.
wIn the event of a simultaneous malfunction of both No. 1 and No. 2 speed sensors, no diagnostic
code will appear and the fail±safe system will not function. However, when driving in the D range,
the transaxle will not up±shift from first gear, regardless of the vehicle speed.
1. Diagnostic code 42 (No. 1 speed sensor circuitry)
Check continuity between ECT ECU
connector SP, terminal and body ground.
(See page AT±32)
Check continuity between ECT ECU
connector SP2 terminal and body ground.
(See page AT±33)
Check wiring between ECT ECU and No. 2
speed sensor.Check wiring between ECT ECU and
combination meter.
2. Diagnostic code 61 (No. 2 speed sensor circuitry
Repair or replace No. 1 speed
sensor.
Check No. 2 speed sensor.
(See page AT±35)Repair or replace No. 2
speed sensor. Substitute another ECT ECU.
Substitute another ECT ECU.Check No. 1 speed sensor.
± AUTOMATIC TRANSAXLETroubleshooting (Diagnosis System) (A140E)AT±19