Lexus ES300 (2002 year). Service manual - part 122

CHASSIS – U150E AUTOMATIC TRANSAXLE

CH-17

161ES23

Solenoid Valve S4

B

3

 Accumulator

Line Pressure

S4 OFF

Except 4th: B

3

 Brake ON

S4 ON

4th: C

3

 Clutch ON

4-5 Shift Valve

C

3

 Accumulator

C

3

B

3

211CH33

Line
Pressure

Solenoid Valve DSL

Solenoid Relay Valve

Lock-up Relay Valve

Line
Pressure

Lock-up ON
Chamber

Lock-up OFF
Chamber

B

2

 Control Valve

“R”

“L”

B

2

3) Function of Solenoid Valve S4

The solenoid valves S4 when set to ON controls the 4-5 shift valve to establish the 5th by changing over
the fluid pressure applied to B

3

 brake and C

3

 clutch.

4) Function of Solenoid Valve DSL

The solenoid valve DSL controls the B

2

 control valve via the solenoid relay valve when the transaxle

is shifted in the R or L position.
During lock-up, the lock-up relay valve is controlled via the solenoid relay valve.

CHASSIS – U150E AUTOMATIC TRANSAXLE

CH-18

157CH19

Line Pressure

Except 5th: B

3

 Brake ON

B

3

 Orifice

Control Valve

B

3

 Apply Fluid Pressure

B

3

 Accumulator

B

3

3. Apply Orifice Control

This control is effected by the B

3

 orifice control valve. The B

3

 orifice control valve has been provided for

the B

3

 brake, which is applied when shifting from 5th to 4th. The B

3

 orifice control valve is controlled by

the amount of the line pressure in accordance with shifting conditions, and the flow volume of the fluid that
is supplied to the B

3

 brake is controlled by varying the size of the orifice in the control valve.

CHASSIS – U150E AUTOMATIC TRANSAXLE

CH-19

ELECTRONIC CONTROL SYSTEM

1. General

The electronic control system of the U150E automatic transaxle consists of the control listed below.

System

Function

U150E

U140E

Clutch Pressure
Control

 Controls the pressure that is applied directly to B

1

 brake

and C

2

 clutch by actuating 2 solenoid valves (SL1, SL2)

in accordance with ECM signals.

 2 solenoid valves (SL1 and SL2) minutely controls the

clutch pressure in accordance with the engine output and
driving conditions.

—



Control
(Refer to CH-24)

 Controls the pressure that is applied directly to B

1

 brake,

C

0

 and C

1

 clutches by actuating 3 solenoid valves (SL1,

SL2, and SL3) in accordance with ECM signals.

 3 solenoid valves (SL1, SL2, and SL3) minutely controls

the clutch pressure in accordance with the engine output
and driving conditions.



—

Line Pressure
Optimal Control
(Refer to CH-26)

Actuates the solenoid valve SLT to control the line pressure
in accordance with information from the ECM and the
operating conditions of the transaxle.





Engine Torque
Control

Retards the engine ignition timing temporarily to improve
shift feeling during up or down shifting.





Shift Control in
Uphill / Downhill

Controls to restrict the 4th upshift or to provide appropriate
engine braking by the ECM to determine whether the
vehicle is traveling uphill or downhill.

—



Uphill / Downhill
Traveling
(Refer to CH-25)

Controls to restrict the 4th or 5th upshift or to provide
appropriate engine braking by the ECM to determine
whether the vehicle is traveling uphill or downhill.



—

Shift Timing Control

The ECM sends current to the solenoid valve SL1 and / or
SL2 based on signals from each sensor and shifts the gear.

—



Shift Timing Control

The ECM sends current to 3 solenoid valves (SL1, SL2, and
SL3) based on signals from each sensor and shifts the gear.



—

Lock-up Timing
Control

The ECM sends current to the solenoid valve DSL based on
signals from each sensor and engages or disengages the
lock-up clutch.





“N” to “D” Squat
Control

When the shift lever is shifted from “N” to “D” position, the
gear is temporarily shifted to 3rd and then to 1st to reduce
vehicle squat.





Diagnosis

When the ECM detects a malfunction, the ECM makes a
diagnosis and memorizes the failed section.





Diagnosis
(Refer to CH-27)

To increase the speed for processing the signals, the 32-bit
CPU of the ECM has been adopted.



—

Fail-safe
(Refer to CH-28)

Even if a malfunction is detected in the sensors or
solenoids, the ECM effects fail-safe control to prevent the
vehicle’s drivability from being affected significantly.





CHASSIS – U150E AUTOMATIC TRANSAXLE

CH-20

ECM

SENSORS

ACTUATORS

CRANKSHAFT

POSITION SENSOR

NE

SOLENOID VALVE SL1

SL1

SOLENOID VALVE SL2

SL2

SOLENOID VALVE SL3

SL3

SOLENOID VALVE SLT

SLT

SOLENOID VALVE S4

S4

SOLENOID VALVE DSL

DSL

SOLENOID VALVE SR

SR

MALFUNCTION

INDICATOR LAMP

W

DATA LINK CONNECTOR 3

SIL
TC

ENGINE COOLANT TEMP.

SENSOR

THW

THROTTLE POSITION SENSOR

VTA1
VTA2

PARK / NEUTRAL

POSITION SWITCH

NSW

R, D, 3, 2

TRANSAXLE CONTROL SWITCH

4, L

SPEED SENSOR

SKID CONTROL ECU

COMBINATION METER

SPD

COUNTER GEAR SPEED

SENSOR

NC

INPUT TURBINE SPEED SENSOR

NT

STOP LIGHT SWITCH

STP

FLUID TEMPERATURE SENSOR

THO

211CH19

2. Construction

The configuration of the electronic control system in the U150E automatic transaxle is as shown in the
following chart.