CH-50 CHASSIS — A750E AND A750F AUTOMATIC TRANSMISSIONS
JELECTRONIC CONTROL SYSTEM
1. General
The electronic control system of the A750E and A750F automatic transmissions consists of the controls listed
below.
System Function
· Controls the pressure that is applied directly to B1 brake and C1 clutch by
actuating the linear solenoid valves SL1 and SL2 in accordance with the ECM
Clutch Pressure Control signals.
· The solenoid valves SLT and SL1 minutely control the clutch pressure in
accordance with the engine output and driving conditions.
Actuates the solenoid valve SLT to control the line pressure in accordance with
Line Pressure Control
information from the ECM and the operating conditions of the transmission.
Retards the ignition timing temporarily to improve shift feeling during up or
Engine Torque Control
down shifting.
The ECM sends current to the solenoid valves S1, S2 and/or SR based on signals
Shift Timing Control
from each sensor and shifts the gear.
The ECM sends current to the shift solenoid valve SLU based on signals from
Lock-up Timing Control
each sensor and engages or disengages the lock-up clutch.
When the shift lever is shifted from “N” to “D” position, the gear is temporarily
“N” to “D” Squat Control
shifted to 2nd and then to 1st to reduce vehicle squat.
Based on the signals from various sensors, the ECM determines the road
AI (Artificial Intelligence)
conditions and the intention of the driver. Thus, the shift pattern is automatically
-SHIFT Control
regulated to an optimal level, thus improving drivability.
When the ECM detects a malfunction, it makes a diagnosis and memorizes the
Diagnosis
failed section.
If a malfunction is detected in the sensors or solenoids, the ECM effects fail-safe
Fail-safe
control to prevent the vehicle’s drivability from being affected significantly.
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CHASSIS — A750E AND A750F AUTOMATIC TRANSMISSIONS CH-51
2. Construction
The configuration of the electronic control system in the new Fortuner/Hilux SW4 A750E and A750F is as
shown in the following charts.
VG S1
AIR FLOW METER SOLENOID VALVE S1
CRANKSHAFT POSITION NE
SENSOR
S2
SOLENOID VALVE S2
THROTTLE POSITION VTA1
SENSOR VTA2
ACCELERATION PEDAL VPA SL1+
SOLENOID VALVE SL1
POSITION SENSOR VPA2 SL1-
THW
WATER TEMP. SENSOR
SL2+
SOLENOID VALVE SL2
CH
NSW SL2-
NEUTRAL START SWITCH
R, D, 3, 2
SHIFT LOCK ECU SLT+
SOLENOID VALVE SLT
SLT-
TRANSMISSION CONTROL 4, L
SWITCH
ECM
SLU+
SOLENOID VALVE SLU
SPEED SENSOR SLU-
SPD
COMBINATION METER
SR
SOLENOID VALVE SR
NT+
INPUT SPEED SENSOR
NT-
SP2+ IGT1~IGT6
OUTPUT SPEED SENSOR
SP2- IGNITION COIL with IGNITER
THO1 IGF
ATF TEMP. SENSOR NO. 1
THO2
ATF TEMP. SENSOR NO. 2 COMBINATION METER
STP OILW
STOP LIGHT SWITCH ATF TEMP. WARNING LIGHT*
ST1-
W CHECK ENGINE
CENTER DIFFERENTIAL 4WD WARNING LIGHT
LOCK POSITION SWITCH*
TFN
TRANSFER NEUTRAL SWITCH* TC
L4 DLC3
L4 POSITION SWITCH* SIL
WFSE
00LCH006Y
*: Models with A750F automatic transmission
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CH-52 CHASSIS — A750E AND A750F AUTOMATIC TRANSMISSIONS
3. Layout of Main Components
Check Engine Warning Light
ECM
ATF Temp.
Warning Light*
Stop Light Switch
DLC3
Shift Lock ECU
· Transmission Control Switch
Solenoid Valve SL1
Solenoid Valve S1
Solenoid Valve
SLT
Solenoid Valve S2
Solenoid Valve SR
Solenoid Valve
SLU
Solenoid Valve
SL2
Neutral Start Switch
Input Speed Sensor
ATF Temp. Sensor No. 1
ATF Temp. Sensor No. 2
Output Speed Sensor
00MCH031Y
*: Models with A750F automatic transmission
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CHASSIS — A750E AND A750F AUTOMATIC TRANSMISSIONS CH-53
4. Construction and Operation of Main Components
ATF Temperature Sensors No. 1 and No. 2
D ATF temperature sensor No. 1 (THO1) is used for hydraulic pressure control. This sensor is used for
revision of clutch and brake pressure to ensure smooth shift quality every time.
D ATF temperature sensor No. 2 (THO2) is used for shifting of the shift timing control of ECT when the
ATF temperature is high. However, on the 4WD model, it is also used for the ATF temperature warning
light.
ATF Temperature Sensor No. 1 (THO1)
CH
Front
229LC132
ATF Temperature Sensor No. 2 (THO2)
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CH-54 CHASSIS — A750E AND A750F AUTOMATIC TRANSMISSIONS
Transmission Control Switch and Neutral Start Switch
The ECM uses these switches to detect the shift position.
D The neutral start switch sends the R, D, 3, 2, and NSW position signals to the ECM. It also sends signals
for the shift position indicator light (P, R, N, and 3) in the combination meter (only for Optitron type).
D The transmission control switch is located in the shift lock ECU. This switch sends the 4th and L signals
to the ECM. It also sends signals for the shift position indicator light (D, 4, 2 and L) in the combination
meter (only for Optitron type).
" Wiring Diagram A
ECM
Neutral Start Switch NSW R D 4 3 2 L
NSW Shift Lock ECU
P
R
N
D NSSD
3 AT4
2
ATD
NSSL
ATL
AT2
P R N D 4 3 2 L
Combination Meter
(Only for Optitron Type)
279CH17
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CHASSIS — A750E AND A750F AUTOMATIC TRANSMISSIONS CH-55
Input Speed Sensor and Output Speed Sensor
The A750E and A750F automatic transmissions use an input speed sensor (for the NT signal) and output
speed sensor (for the SP2 signal). Thus, the ECM can detect the timing of the shifting of the gears and
appropriately control the engine torque and hydraulic pressure in response to the 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 clutch drum is used as the timing
rotor for this sensor.
D The output speed sensor detects the speed of the output shaft. The parking gear on the rear planetary gear
is used as the timing rotor for this sensor.
Clutch Drum Output Speed Sensor
(Timing Rotor)
CH
Parking Gear
(Timing Rotor)
Input Speed Sensor 232CH91
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CH-56 CHASSIS — A750E AND A750F AUTOMATIC TRANSMISSIONS
5. Clutch Pressure Control
Clutch to Clutch Pressure Control
This control is used for shifting from the 4th to 5th gear and from the 5th to 4th gear.
It actuates solenoid valves SL1 and SL2 in accordance with the signals from the ECM, and guides this output
pressure directly to the control valves B1 and C1 in order to regulate the line pressure that acts on the B1
brake and C1 clutch.
As a result, high response and excellent shift characteristics have been achieved.
ECM
· Input Speed Sensor
SL1 SL2 · Output Speed Sensor
· Throttle Position Sensor
· Air Flow Meter
· ATF Temp. Sensor No. 1
C1 Control Valve B1 Control Valve · Water Temp. Sensor
· Accelerator Pedal Position
Sensor
C1 B1
C1 B1
4th ! 5th OFF ON
5th ! 4th ON OFF
Line Pressure 232CH141
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CHASSIS — A750E AND A750F AUTOMATIC TRANSMISSIONS CH-57
Clutch Pressure Optimal Control
The ECM monitors the signals from various types of sensor such as the input speed sensor, allowing
solenoid valves SLT and SL1 to minutely control the clutch pressure in accordance with engine output and
driving conditions. As a result, smooth shift characteristics have been achieved.
Target rpm
Change Ratio
Input ECM
Shaft rpm
Practical rpm Change Ratio
Time
Input Speed
Sensor Output Speed
CH
Sensor
ATF Temp.
Sensor No. 1
Accumulator
Control Valve
Clutch Solenoid Valve Output
Brake SL1, SLT Shaft
Pressure Torque
Solenoid Drive Signal Time
279CH109
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CH-58 CHASSIS — A750E AND A750F AUTOMATIC TRANSMISSIONS
6. Line Pressure Optimal Control
Through the use of the solenoid valve SLT, the line pressure is optimally controlled in accordance with the
engine torque information, as well as with the internal operating conditions of the torque converter and the
transmission.
Accordingly, the line pressure can be controlled minutely in accordance with the engine output, traveling
condition, and the ATF temperature, thus achieving smooth shift characteristics and optimizing the workload
in the oil pump.
Line Pressure Intake Air Volume
Throttle Valve Opening
Water Temp.
ECM Engine rpm
Primary Regulator
Input Speed
ATF Temp.
Shift Position
Solenoid Drive Signal
Fluid
Pressure
Current
Pump Throttle Pressure
Solenoid Valve SLT
279CH110
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CHASSIS — A750E AND A750F AUTOMATIC TRANSMISSIONS CH-59
7. AI (Artificial Intelligence)-SHIFT Control
General
In addition to the switching of the shift pattern through the pattern select switch, the AI-SHIFT control
enables the ECM to estimate the road conditions and the driver’s intention in order to automatically switch
to the optimal shift pattern. As a result, a comfortable ride has been achieved.
Input Signals
AI-SHIFT
Basic Shift
Pattern Control
Sensor Signals
Road Condition
Uphill/Downhill Driving
· Throttle Valve
Opening Angle Estimating the Grade
· Vehicle Speed
· Engine Speed Road Condition CH
· Brake Signal Support Control
Small Large
: Criterion Acceleration
: Actual Acceleration
Calculated by ECM Driver’s Intention
· Acceleration
· Vehicle Pedal Operation Estimating
Driver’s Driver’s Intention
Acceleration · Vehicle Support Control
Condition Intention
02ACH062Y
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CH-60 CHASSIS — A750E AND A750F AUTOMATIC TRANSMISSIONS
Road Condition Support Control
Under road condition support control, the ECM identifies throttle valve opening angle, accelerator pedal
operating angle and the vehicle speed whether the vehicle is being driven uphill or downhill.
To achieve an optimal drive force while driving uphill, this control prevents the transmission from
upshifting to the 4th or 5th gear. To achieve an optimal engine brake effect while driving downhill, this
control automatically downshifts the transmission to the 4th or 3rd gear.
5th
5th 4th 5th 3rd 5th 4th (Brake Operating) Without Control
With Control
5th 4th 3rd 4th 3rd 4th 5th
229LC183
Driver’s Intention Support Control
Under driver’s intention support control, the driver’s intention is estimated based on the accelerator
operation and vehicle condition to switch to a shift pattern that is well-suited to each driver.
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CHASSIS — A750E AND A750F AUTOMATIC TRANSMISSIONS CH-61
8. Diagnosis
D When the ECM detects a malfunction, it makes a diagnosis and memorizes the failed section. Furthermore,
the check engine warning light in the combination meter illuminates or blinks to inform the driver.
D At the same time, the DTCs (Diagnosis Trouble Codes) are stored in memory. The DTCs can be read by
connecting an intelligent tester II to 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 input speed sensor malfunction, shift control is effected through the
output speed sensor signal (SP2).
Input Speed Sensor (NT)
During an input speed sensor malfunction, shift control is effected through the
input speed sensor signal (SPD). CH
During an output speed sensor malfunction, shift control is effected through the
input speed sensor signal (NT).
Output Speed Sensor (SP2)
During an output speed sensor malfunction, shift control is effected through the
input speed sensor signal (SPD).
During an ATF temp. sensor No. 1 malfunction, up-shifts to 5th and lock-up
clutch control are prohibited.
ATF Temp. Sensor No. 1
During an ATF temp. sensor No. 1 malfunction, the system effects control by
fixing the ATF temperature at 80°C (176°F).
The current to the failed solenoid valve is cut off and control is effected by
Solenoid Valves operating the other solenoid valves with normal operation.
S1, S2 and SR Shift control is effected depending on the failed solenoid as described in the table
on the next page.
Solenoid Valves During a solenoid valve SL1 or SL2 malfunction, up-shifts to 5th and lock-up
SL1 and SL2 clutch control are prohibited.
During a solenoid valve SLU malfunction, the current to the solenoid valve is
Solenoid Valve SLU
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 optimal control, thus increasing shift-shock.
However, shifting is effected through normal clutch pressure control.
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CH-62 CHASSIS — A750E AND A750F AUTOMATIC TRANSMISSIONS
Normal Solenoid Valve S1 Malfunction
Position Solenoid Valve Solenoid Valve
Gear Gear
S1 S2 SR SL1 SL2 S1 S2 SR SL1 SL2
OFF ! 4th !
ON OFF OFF OFF ON 1st ´ OFF OFF ON
ON 3rd
ON ON OFF OFF ON 2nd ´ ON OFF OFF ON 3rd
D OFF ON OFF OFF ON 3rd ´ ON OFF OFF ON 3rd
OFF OFF OFF OFF ON 4th ´ OFF OFF OFF ON 4th
OFF OFF ON ON OFF 5th ´ OFF ON ON OFF 5th
OFF ! 4th !
ON OFF OFF OFF ON 1st ´ OFF OFF ON
ON 3rd
4 ON ON OFF OFF ON 2nd ´ ON OFF OFF ON 3rd
OFF ON OFF OFF ON 3rd ´ ON OFF OFF ON 3rd
OFF OFF OFF OFF ON 4th ´ OFF OFF OFF ON 4th
OFF ! ON ! 3rd !
ON OFF OFF OFF ON 1st ´ OFF OFF
ON OFF 3rd (E/B)
3 ON ON OFF OFF ON 2nd ´ ON OFF OFF
ON ! 3rd !
OFF 3rd (E/B)
OFF ON OFF OFF OFF 3rd (E/B) ´ ON OFF OFF OFF 3rd (E/B)
ON OFF OFF OFF ON 1st ´ OFF OFF OFF ON 1st
2
ON ON ON OFF OFF 2nd (E/B) ´ ON ON OFF OFF 3rd (E/B)
L ON OFF OFF OFF OFF 1st (E/B) ´ OFF OFF OFF OFF 1st (E/B)
Solenoid Valve S2 Malfunction Solenoid Valve SR Malfunction
Position Solenoid Valve Solenoid Valve
Gear Gear
S1 S2 SR SL1 SL2 S1 S2 SR SL1 SL2
ON ´ OFF OFF ON 1st ON OFF ´ OFF ON 1st
ON ! 1st !
´ OFF OFF ON ON ON ´ OFF ON 2nd
OFF 4th
D OFF ´ OFF OFF ON 4th OFF ON ´ OFF ON 3rd
OFF ´ OFF OFF ON 4th OFF OFF ´ OFF ON 4th
OFF ´ ON ON OFF 5th OFF OFF ´ ON OFF 4th
ON ´ OFF OFF ON 1st ON OFF ´ OFF ON 1st
ON ! 1st !
´ OFF OFF ON ON ON ´ OFF ON 2nd
4 OFF 4th
OFF ´ OFF OFF ON 4th OFF ON ´ OFF ON 3rd
OFF ´ OFF OFF ON 4th OFF OFF ´ OFF ON 4th
ON ´ OFF OFF ON 1st ON OFF ´ OFF ON 1st
ON ! ON ! 1st !
´ OFF OFF ON ON ´ OFF ON 2nd
3 OFF OFF 3rd (E/B)
OFF ! 3rd (E/B)
OFF ´ OFF OFF OFF 3rd (E/B) OFF ON ´ OFF
ON ! 3rd
ON ´ OFF OFF ON 1st ON OFF ´ OFF ON 1st
2 ON ! OFF ! 2nd (E/B)
´ ON OFF ON ON ´ OFF OFF 2nd
OFF ON ! 4th
L ON ´ OFF OFF OFF 1st (E/B) ON OFF ´ OFF OFF 1st (E/B)
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CHASSIS — A750E AND A750F AUTOMATIC TRANSMISSIONS CH-63
Solenoid Valves S1 and S2 Malfunction Solenoid Valves S1 and SR Malfunction
Position Solenoid Valve Solenoid Valve
Gear Gear
S1 S2 SR SL1 SL2 S1 S2 SR SL1 SL2
OFF ! 4th !
´ ´ OFF OFF ON 4th ´ ´ OFF ON
ON 3rd
´ ´ OFF OFF ON 4th ´ ON ´ OFF ON 3rd
D ´ ´ OFF OFF ON 4th ´ ON ´ OFF ON 3rd
´ ´ OFF OFF ON 4th ´ OFF ´ OFF ON 4th
ON ! OFF !
´ ´ ON ON OFF 5th ´ OFF ´ 4th
OFF ON
OFF ! 4th !
´ ´ OFF OFF ON 4th ´ ´ OFF ON
ON 3rd
4 ´ ´ OFF OFF ON 4th ´ ON ´ OFF ON 3rd
´ ´ OFF OFF ON 4th ´ ON ´ OFF ON 3rd
´ ´ OFF OFF ON 4th ´ OFF ´ OFF ON 4th
ON ! 3rd ! OFF !
´ ´ OFF OFF ´ ´ OFF ON 3rd
OFF 3rd (E/B) ON
3 ´ ´ OFF OFF
ON ! 3rd !
´ ON ´ OFF ON 3rd CH
OFF 3rd (E/B)
OFF ! 3rd (E/B)
´ ´ OFF OFF OFF 3rd (E/B) ´ ON ´ OFF
ON ! 3rd
´ ´ OFF OFF ON 1st ´ OFF ´ OFF ON 1st
2 OFF !
´ ´ ON OFF 4th ´ ON ´ OFF OFF 2nd
ON
L ´ ´ OFF OFF OFF 1st (E/B) ´ OFF ´ OFF OFF 1st (E/B)
Solenoid Valves S2 and SR Malfunction Solenoid Valves S1, S2 and SR Malfunction
Position Solenoid Valve Solenoid Valve
Gear Gear
S1 S2 SR SL1 SL2 S1 S2 SR SL1 SL2
ON ´ ´ OFF ON 1st ´ ´ ´ OFF ON 4th
ON ! 1st !
´ ´ OFF ON ´ ´ ´ OFF ON 4th
OFF 4th
D OFF ´ ´ OFF ON 4th ´ ´ ´ OFF ON 4th
OFF ´ ´ OFF ON 4th ´ ´ ´ OFF ON 4th
ON ! OFF ! ON ! OFF !
OFF ´ ´ 4th ´ ´ ´ 4th
OFF ON OFF ON
ON ´ ´ OFF ON 1st ´ ´ ´ OFF ON 4th
ON ! 1st !
´ ´ OFF ON ´ ´ ´ OFF ON 4th
4 OFF 4th
OFF ´ ´ OFF ON 4th ´ ´ ´ OFF ON 4th
OFF ´ ´ OFF ON 4th ´ ´ ´ OFF ON 4th
ON ´ ´ OFF ON 1st ´ ´ ´ OFF ON 3rd
ON ! 1st !
´ ´ OFF ON ´ ´ ´ OFF ON 3rd
3 OFF 3rd
OFF ! 3rd (E/B) OFF ! 3rd (E/B)
OFF ´ ´ OFF ´ ´ ´ OFF
ON ! 3rd ON ! 3rd
ON ´ ´ OFF ON 1st ´ ´ ´ OFF ON 1st
2 OFF ! 1st (E/B) OFF ! 1st (E/B)
ON ´ ´ OFF ´ ´ ´ OFF
ON ! 1st ON ! 1st
L ON ´ ´ OFF OFF 1st (E/B) ´ ´ ´ OFF OFF 1st (E/B)
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