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Toyota Sequoia (2005). Manual - part 1000
188
SEQUOIA (EM00Z0U)
ECT and A/T Indicator
Previous automatic transmissions have selected each gear shift using mechanically controlled throttle hydraulic pressure,
governor hydraulic pressure and lock–up hydraulic pressure. The electronically controlled transmission, however, electrically
controls the line pressure, throttle pressure, lock–up pressure and accumulator pressure etc. through the solenoid valve. The
electronically controlled transmission is a system which precisely controls gear shift timing and lock–up timing in response to
the vehicle’s driving conditions and the engine condition detected by various sensors. It makes smooth driving possible by
shift selection for each gear which is the most appropriate to the driving conditions at that time, and by preventing downing,
squat and gear shift shock when starting off.
1. Gear Shift Operation
When driving, the engine warm up condition is input as a signal to TERMINAL THW of the engine control module from the
engine coolant temp. sensor and the vehicle speed signal from vehicle speed sensor is input to TERMINAL SP2+ of the
engine control module. At the same time, the throttle valve opening signal from the throttle position sensor is input to
TERMINALS VTA1 and VTA2 of the engine control module as throttle angle signal.
Based on these signals, the engine control module selects the best shift position for the driving conditions and sends current
to the electronically controlled transmission solenoid.
2. Line Hydraulic Pressure Control
The engine control module adjusts the line hydraulic pressure to the optimal level by controlling TERMINAL SLT+ of the
module according to the engine torque data. This realizes the smooth gear shifting.
3. High Response Gear Shifting Control
The engine control module performs the high response engine torque up control to control the ignition–timing lag as well as
opening the electronic throttle when shifting down. By doing this, the gear shifting is performed in a short period of time.
Moreover, the engine control module uses the orifice switching control, which optimizes the speed of applying and reducing
the hydraulic pressure. And it realizes the fine shifting condition by applying and reducing hydraulic pressure slowly when
the gear shifting shock is important and quickly when the high response is required.
4. Clutch Hydraulic Pressure Control
The engine control module controls the clutch operation in the optimal timing and with the best hydraulic pressure according
to the engine torque data and the number of the clutch revolution
5. Lock–Up and Flexible Lock–Up Control
The engine control module carries out the lock–up control by controlling the TERMINAL SLU+ of the module according to
the shift position, vehicle speed, throttle opening degree and running conditions. The engine control module also steadily
keeps applying the lock–up clutch a delicate slippage to improve the transmission efficiency (Fuel efficiency) of the torque
converter.
6. Stop Light SW Circuit
If the brake pedal is depressed (Stop light SW on) when driving in lock–up condition, a signal is input to TERMINAL STP of
the engine control module. The engine control module operates and cuts the current to the solenoid to release lock–up.
7. AI–Shift Control
The engine control module judges whether the road is downslope or upslope by detecting the throttle opening degree or the
vehicle’s speed. Moreover it can expect the winding roads by detecting the turning condition of the vehicle. The engine
control module keeps unnecessary shifting up from the fourth gear from operating and carries out the automatic shifting
down to the third gear in order to control the vehicle running according to the road conditions. The engine control module
also reads the driver’s intention during driving from his (her) accelerating operation and the running conditions of the vehicle.
As a result of that, ideal shifting patters for each driver are automatically selected without any switching operations.
: Parts Location
Code
See Page
Code
See Page
Code
See Page
A37
42
E8
E
43
J53
A
44
C5
A
42
J5
41
J54
B
44
C6
B
42
J8
44
O1
41
D6
43
J12
44
O3
45
E1
40
J16
44
P1
41
E2
40
J17
44
S14
45
E4
A
43
J18
44
T14
41
E5
B
43
J43
44
V1
41
E6
C
43
J51
A
44
V2
41
E7
D
43
J52
B
44
System Outline