Lexus ES300 (2002 year). Manual — part 123

CHASSIS – U150E AUTOMATIC TRANSAXLE

CH-21

211CH20

Solenoid Valve SR

Malfunction Indicator Lamp

ECM

Transaxle Control Switch

DLC3

Stop Light Switch

Counter Gear Speed Sensor

Input Turbine Speed Sensor

Park / Neutral Position Switch

Solenoid Valve SL1

Solenoid Valve SLT

Solenoid Valve SL3

Solenoid Valve S4

Solenoid Valve SL2

Solenoid Valve DSL

Fluid Temperature Sensor

3. Layout of Component

CHASSIS – U150E AUTOMATIC TRANSAXLE

CH-22

181CH11

Lower Valve Body

Fluid Temperature
Sensor

211CH16

Input Turbine
Speed Sensor

Counter Gear
Speed Sensor

4. Construction and Operation of Main Component

Fluid Temperature Sensor

A fluid temperature sensor is installed in the valve body for direct detection of the fluid temperature.
Fluid temperature sensor is used for revision of clutches and brakes pressure to keep smooth shift quality
every time.

Speed Sensors

The U150E automatic transaxle has adopted an input turbine speed sensor (for the NT signal) and a counter
gear speed sensor (for the NC 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.

The input turbine speed sensor detects the input speed of the transaxle. The direct clutch (C

2

) drum is

used as the timing rotor for this sensor.

The counter gear speed sensor detects the speed of the counter gear. The counter drive gear is used as

the timing rotor for this sensor.

CHASSIS – U150E AUTOMATIC TRANSAXLE

CH-23

211CH47

Transaxle Control Switch

Transaxle Control Switch

The transaxle control switch is installed inside
shift lever assembly to detect the shift lever
position (“4th” or “D” and “2nd” or “L”) and to
inform ECM the shift position indicator light in
the combination meter.

CHASSIS – U150E AUTOMATIC TRANSAXLE

CH-24

211CH15

Input Turbine Speed Sensor

Counter Gear Speed Sensor

Throttle Position Sensor

Mass Air Flow Meter

Fluid Temperature Sensor

Engine Coolant Temp. Sensor

B

1

C

0

C

1

2nd
3rd
4th

: ON x: OFF

B

1

Control

Valve

B

1

Accumulator

C

0

Control

Valve

B

1

SL2

ECM

Sensor Signal

SL3

SL1

C

0

Accumulator

C

0

C

1

C

1

Control

Valve

C

1

Accumulator

x

x

x

211CH17

Input Shaft
rpm

Target rpm Change Ratio

Practical rpm Change Ratio

Time

Input Turbine
Speed Sensor

ECM

Signals from Various Sensors

Engine rpm

Engine Torque Information

Fluid Temperature

SL1

SL2

SL3

Clutch / Brake
Pressure

Solenoid Drive Signal

Output Shaft
Torque

Time

5. Clutch Pressure Control

Clutch to Clutch Pressure Control

This control has been adopted for shifting from the 1st to 2nd gear, from the 2nd to 3rd gear, and from the
3rd to 4th gear.
Actuates solenoid valves SL1, SL2, and SL3 in accordance with the signals from the ECM, and guides this
output pressure directly to the control valves B

1

, C

0

, and C

1

in order to regulate the line pressure that acts

on the B

1

brake, C

0

, and C

1

clutches.

As a result, compact B

1

, C

0

, and C

1

accumulators without a back pressure chamber have been realized.

Clutch Pressure Optimal Control

The ECM monitors the signals from various types of sensor such as the input turbine speed sensor, allowing
shift solenoid valves SL1, SL2, and SL3 to minutely control the clutch pressure in accordance with engine
output and driving conditions.
As a result, smooth shift characteristics have been realized.