CH-20 CHASSIS — A340E, A340F, A343E AND A343F AUTOMATIC TRANSMISSIONS

JELECTRONIC CONTROL SYSTEM

1. General
The electronic control system of the A340E, A340F, A343E and A343F automatic transmissions consists of
the controls listed below:
Transmission Type
System Function A340E, A343E,
A340F A343F
The ECM or ECT ECU sends current to the solenoid valve
Shift Timing Control S1 and/or S2 based on signals from each sensor and shifts the f f
gear.
The ECM or ECT ECU sends current to the solenoid valve
Lock-up Timing Control SL based on signals from each sensor and engages or f f
disengages the lock-up clutch.
Actuates the solenoid valve SLT to control the line pressure
Line Pressure Control in accordance with information from ECM or ECT ECU and f f
the operating conditions of the transmission.
Retards the ignition timing temporarily to increase shift
— f
feeling during up or down shifting.
Engine Torque Control
Reduces the fuel injection volume temporarily to increase
f —
shift feeling during up or down shifting.
When the shift lever is shifted from “N” to “D” position, the
“N” or “D”
gear is temporarily shifted to 2nd and then 1st to reduce f f
Squat Control
vehicle squat.
When the ECM or ECT ECU detects a malfunction, the ECU
Diagnosis f f
makes a diagnosis and memorizes the failed section.
Controls other normally operating components, permitting
Fail-safe continued driving when malfunctions occur in the electrical f f
circuit.

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 CHASSIS — A340E, A340F, A343E AND A343F AUTOMATIC TRANSMISSIONS CH-21

2. Construction
The configuration of the electronic control system in the A340E, A340F, A343E and A343F automatic
transmissions are as shown in the following charts.

" A340E and A340F A

THOC S1
ATF TEMP. SENSOR SOLENOID VALVE S1

VEHICLE SPEED SENSOR*1

or SPEED SENSOR*2
S2
SPD1 SOLENOID VALVE S2
COMBINATION METER

NSW
NEUTRAL START SWITCH
R, D, 2, L SL
SOLENOID VALVE SL
SHIFT LOCK ECU
CH
TRANSMISSION 3
CONTROL SWITCH SLT+
ECT SOLENOID VALVE SLT
NCO+, NCO- ECU SLT-
INPUT SPEED SENSOR

SP2+, SP2-
OUTPUT SPEED SENSOR COMBINATION METER
OILW ATF TEMP.
TRANSFER NEUTRAL TFN
WARNING LIGHT*3
POSITION SWITCH*3
L4
L4 POSITION SWITCH*3

STP SIL
STOP LIGHT SWITCH DLC3
WFSE
CAN+, CAN-
#1
CRANKSHAFT POSITION NE No. 1 INJECTOR
SENSOR #2
No. 2 INJECTOR
#3 EDU
No. 3 INJECTOR
#4
VPA No. 4 INJECTOR
ACCELERATOR PEDAL ECM
POSITION SENSOR VPA2
INJF
COMBINATION METER

CHECK ENGINE
THW WARNING LIGHT
WATER TEMP. SENSOR W

: CAN (Controller Area Network)

00LCH001I

*1: Models without brake control system

*2: Models with brake control system
*3: Models with A340F automatic transmission

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CH-22 CHASSIS — A340E, A340F, A343E AND A343F AUTOMATIC TRANSMISSIONS

" A343E and A343F A

CRANKSHAFT POSITION NE S1
SOLENOID VALVE S1
SENSOR

THROTTLE POSITION VTA1

SENSOR VTA2
S2
SOLENOID VALVE S2
ACCELERATOR PEDAL VPA
POSITION SENSOR VPA2

THW
WATER TEMP. SENSOR
SL
SOLENOID VALVE SL
THOC
ATF TEMP. SENSOR

NSW
NEUTRAL START SWITCH
R, 2, L SLT
SOLENOID VALVE SLT

SHIFT LOCK ECU

TRANSMISSION 3
CONTROL SWITCH
IGT1 - IGT4
ECM
IGNITION COIL with IGNITER
VEHICLE SPEED SENSOR*1 IGF1
or SPEED SENSOR*2

SPD
COMBINATION METER

NCO+ COMBINATION METER

INPUT SPEED SENSOR
NCO-

SP2+ OILW ATF TEMP.

OUTPUT SPEED SENSOR WARNING LIGHT*3
SP2-

W CHECK ENGINE
CENTER DIFFERENTIAL 4WD WARNING LIGHT
LOCK POSITION SWITCH*3

L4
L4 POSITION SWITCH*3

STP SIL, TC
STOP LIGHT SWITCH DLC3
ST1-

00LCH002Y
*1: Models without brake control system
*2: Models with brake control system
*3: Models with A343F automatic transmission

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 CHASSIS — A340E, A340F, A343E AND A343F AUTOMATIC TRANSMISSIONS CH-23

3. Layout of Main Components

Check Engine Warning Light

ECM

ECT ECU*2

ATF Temperature
Warning Light*1

Stop Light Switch

CH
DLC3
Shift Lock ECU
· Transmission Control
ATF Temperature Sensor Switch

Neutral Start Switch Neutral Start Switch

LHD Model

ATF Temperature Sensor

Output Speed Sensor

A340F and A340F A343E and A343F

Vehicle Speed
Output Speed Sensor*3
Solenoid Valve SLT Sensor

A340E and A343E

Solenoid Valve S1
Input Speed
Sensor Solenoid Valve S2
A340F and A343F Solenoid Valve SL
00MCH030Y

*1: Models with A340F or A343F automatic transmission

*2: Models with A340E or A340F automatic transmission
*3: Models without brake control system

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CH-24 CHASSIS — A340E, A340F, A343E AND A343F AUTOMATIC TRANSMISSIONS

4. Construction and Operation

Transmission Control Switch and Neutral Start Switch

The ECM or ECT ECU uses these switches to detect the shift position.
D The neutral start switch sends the R, D*, 2, L and NSW position signals to the ECM or ECT ECU. It also
sends signals for the shift indicator light (P, R, N, 2 and L) in the combination meter (only for Optitron
type).
D The transmission control switch is located in the shift lock ECU. This switch sends the 3rd signal to the
ECM or ECT ECU. It also sends signals for the shift position indicator light (D and 3rd) in the
combination meter (only for Optitron type).

" Wiring Diagram A

Neutral Start Switch ECM or ECT ECU

To Starter NSW NSW R D* 3 2 L

Shift Lock ECU
Relay
P Transmission
R Control ECU
N
+B D NSSD
2
AT3
L
ATD

P R N D 3 2 L

Combination Meter
(Only for Optitron Type)
00JCH001Y

*: Except models with 2TR-FE engine

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 CHASSIS — A340E, A340F, A343E AND A343F AUTOMATIC TRANSMISSIONS CH-25

Input Speed Sensor and Output Speed Sensor

These automatic transmissions use an input speed sensor (for NC0 signal) and an output speed sensor (for
SP2 signal). Thus, the ECM or ECT ECU can detect the timing of the shifting of the gears and appropriately
control the engine torque and hydraulic pressure in response to various conditions.
D These speed sensors are the pick-up coil type.
D The input speed sensor detects the input speed of the transmission. The OD direct clutch drum is used
as the timing rotor for this sensor.
D The output speed sensor detects the speed of the output shaft.

Input Speed Sensor

(for NC0 Signal) Output Speed Sensor
(for SP2 Signal)

CH

00LCH004Y

A340E and A343E

Input Speed Sensor

(for NC0 Signal) Output Speed Sensor
(for SP2 Signal)

00LCH005Y

A340F and A343F

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CH-26 CHASSIS — A340E, A340F, A343E AND A343F AUTOMATIC TRANSMISSIONS

5. Line Pressure Control

In order to obtain a predetermined line pressure characteristic in accordance with to the each sensor signal,
the ECM or ECT ECU activates the solenoid valve SLT to regulate the throttle pressure.
This makes it possible for the primary regulator valve to precisely and minutely control the line pressure in
accordance with the engine output, and thus provide smoother shift characteristics.

" A340E and A340F A

Primary Regulator Solenoid Valve SLT

Valve
ATF Temp. Sensor
Shift Position
Throttle Pressure ECT ECU Input Speed Sensor
Output Speed Sensor
Vehicle Speed Sensor*1
or Speed Sensor*2
CAN
Accelerator Pedal
Line Pressure

Position Sensor
ECM Water Temp. Sensor

Oil Pump Line Crankshaft Position

Pressure Sensor
Throttle Valve
Opening Angle
271CH41

" A343E and A343F A

ECM
Primary Regulator Solenoid Valve SLT
Valve
ATF Temp. Sensor
Shift Position
Throttle Pressure Transmission
CPU Input Speed Sensor
Output Speed Sensor
Vehicle Speed Sensor*1
or Speed Sensor*2
Accelerator Pedal
Position Sensor
Line Pressure

Engine Water Temp. Sensor

CPU
Oil Pump Line Crankshaft Position
Pressure Sensor
Throttle Valve
Opening Angle
237CH30

*1: Models without brake control system

*2: Models with brake control system

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 CHASSIS — A340E, A340F, A343E AND A343F AUTOMATIC TRANSMISSIONS CH-27

6. Engine Torque Control (for A340E and A340F)

Engagement of the clutches and brakes of the planetary gear unit in the transmission is controlled smoothly
by momentarily reducing the fuel injection volume when gears are shifted up or down in the transmission.
When the ECT ECU judges gear shift timing according to signals, it activates the shift control solenoid valves
to perform gear shifting. When the gear shifting starts, the ECM reduces the fuel injection volume to reduce
the engine torque. As a result, engagement force of the clutches and brakes of the planetary gear units is
weakened and the gear change is performed smoothly.

Vehicle Speed Signal

ECM

CAN
Accelerator Pedal
ECT ECU Position Signal
(b)
CH
(d)

Injector Speed Signal

(c)
(a)

(e)

Crankshaft
Position Sensor
Engine
Torque When engine torque is reduced, clutches and
brakes are engaged with less force and gear
shifting is performed smoothly.
Normal Reducing

271CH05

(a) : Gear Information

(b) : Determination of Fuel Injection Reduce Volume
(c) : Gear Shifting
(d) : Reducing Fuel Injection Volume
(e) : Torque Reduction

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CH-28 CHASSIS — A340E, A340F, A343E AND A343F AUTOMATIC TRANSMISSIONS

7. Engine Torque Control (for A343E and A343F)

Engagement of the clutches and brakes of the planetary gear unit in the transmission is controlled smoothly
by momentarily retarding the engine ignition timing when gears are shifted up or down in the transmission.
When the ECM judges gear shift timing according to signals, it activates the shift control solenoid valves to
perform gear shifting. When the gear shifting starts, the ECM retards the engine ignition timing to reduce
the engine torque. As a result, engagement force of the clutches and brakes of the planetary gear units is
weakened and the gear change is performed smoothly.

ECM
Vehicle Speed Signal
(b)
Throttle Position Signal

(d)

Ignition Coil with Igniter (c) (a) Speed Signal

(e)

Crankshaft
Position Sensor

Engine When engine torque is reduced, clutches and

Torque brakes are engaged with less force and gear
shifting is performed smoothly.
Normal Retarding 271CH43

(a) : Gear Information

(b) : Determination of Ignition Timing Retard Angle
(c) : Gear Shifting
(d) : Retarding Ignition Timing
(e) : Torque Reduction

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 CHASSIS — A340E, A340F, A343E AND A343F AUTOMATIC TRANSMISSIONS CH-29

8. Diagnosis
D When the ECM or ECT ECU detects a malfunction, it makes a diagnosis and memorizes the failed section.
Furthermore, the check engine warning light in the combination meter illuminates to inform the driver.
D At the same time, the DTCs (Diagnostic Trouble Codes) are stored in memory.
D The DTCs can be read by connecting an intelligent tester II to DLC3.
D The DTCs can be read from the number of blinks of the check engine warning light by connecting the SST
(09843-18040) to the TC and CG terminals of the DLC3.
For details, refer to the Fortuner/Hilux SW4 Repair Manual.

9. Fail-safe
This function minimizes the loss of operability when any abnormality occurs in any sensor or solenoid.

" Fail-safe Control List A

Malfunction Part Function

During an output speed sensor malfunction, shift control is effected through the
Output Speed Sensor (SP2) CH
input speed sensor signal (NC0) or engine speed signal (NE).
During a malfunction of ATF temperature sensor, the system effects control by
ATF Temperature Sensor
fixing the ATF temperature at 80°C (176°F).
Solenoid Valves The current to the failed solenoid valve is cut off and control is effected by
S1 and S2 operating the other solenoid valves with normal operation.
During a solenoid valve SL malfunction, the current to the solenoid valve is
Solenoid Valve SL
stopped. This stops lock-up control, thus decreasing fuel economy.
During a solenoid valve SLT malfunction, the current to the solenoid valve is
Solenoid Valve SLT stopped. This stops line pressure control, thus increasing shift-shock. However,
shifting is effected through normal clutch pressure control.

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