1996 ACURA RL KA9 lock

In position in 2nd, 3rd and 4th, and position in 3rd, pressurized fluid is drained from the back of the torque converter

through a passage, causing the lock-up piston to be held against the torque converter cover. As this takes place, the main-

shaft rotates at the same speed as the engine crankshaft. Together with hydraulic control, the PCM optimizes the timing of

the lock-up system. Under certain conditions, the lock-up clutch is applied during deceleration in 3rd and 4th gear.

The lock-up system controls the range of lock-up according to torque converter clutch (lock-up control) solenoid valves A

and B, and the throttle valve. When torque converter clutch solenoid valves A and B activate, modulator pressure

changes. Torque converter clutch solenoid valves A and B are mounted on the torque converter housing, and are con-

trolled by the PCM.

NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.ProCarManuals.com

Description

Lock-up System (cont'd)

No Lock-up

The pressurized fluid regulated by the modulator works on both ends of the lock-up shift valve and on the left side of the

lock-up control valve. Under this condition, the pressures working on both ends of the lock-up shift valve are equal, and

the shift valve is moved to the right side by the tension of the valve spring alone. The fluid from the pump will flow

through the left side of the lock-up clutch to the torque converter; that is, the lock-up clutch is in OFF condition.

NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.ProCarManuals.com

Partial Lock-up

Torque Converter Clutch (Lock-up Control) Solenoid Valve A: ON Torque Converter Clutch (Lock-up Control) Solenoid

Valve B: OFF

The PCM switches the solenoid valve A on to release the modulator pressure in the left cavity of the lock-up shift valve.

The modulator pressure in the right cavity of the lock-up shift valve overcomes the spring force; thus the lock-up shift

valve is moved to the left side.

The line pressure is then separated into the two passages to the torque converter:

Torque Converter Inner Pressure: enters into right side to engage lock-up clutch

Torque Converter Back Pressure: enters into left side to disengage lock-up clutch

The back pressure (F2) is regulated by the lock-up control valve, whereas the position of the lock-up timing valve is deter-

mined by the throttle B pressure, tension of the valve spring, and pressure regulated by the modulator valve. Also the posi-

tion of the lock-up control valve is determined by the back pressure of the lock-up control valve and torque converter pres-

sure regulated by the check valve. With the torque converter clutch solenoid valve B kept off, the modulator pressure is main-

tained in the left side of the lock-up control valve; in other words, the lock-up control valve is moved slightly to the right side.

This slight movement of the lock-up control valve causes the back pressure to be lowered slightly, resulting in partial lock-up.

NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.ProCarManuals.com

Lock-up System (cont'd)

Half Lock-up

Torque Converter Clutch (Lock-up Control) Solenoid Valve A: ON Torque Converter Clutch (Lock-up Control) Solenoid

Valve B: ON

The modulator pressure is released by the solenoid valve B, causing the modulator pressure in the left side of the lock-up

control valve to lower.

Also the modulator pressure in the left cavity of the lock-up timing valve is low. However, throttle B pressure is still low at

this time; consequently, the lock-up timing valve is kept on the right side by the spring force.

With the torque converter clutch solenoid valve B turned on, the lock-up control valve is moved somewhat to the left side,

causing the back pressure (F2) to lower. This allows a greater amount of the fluid (F1) to work on the lock-up clutch so as

to engage the clutch. The back pressure (F2) which still exists prevents the clutch from engaging fully.

NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
DescriptionProCarManuals.com

Full Lock-up

Torque Converter Clutch (Lock-up Control) Solenoid Valve A: ON Torque Converter Clutch (Lock-up Control) Solenoid

Valve B: ON

When the vehicle speed further increases, throttle B pressure is increased in accordance with the throttle opening.

Throttle B pressure (55) flows to the right side of the lock-up timing valve and the lock-up control valve, and they are moved

to the left side. The lock-up timing valve covers the port leading torque converter pressure (90) from the torque converter to

the lock-up control valve. The lock-up control valve uncovers the port to leak the torque converter pressure (94) and (96). As

this takes place, torque converter back pressure is released fully, causing the lock-up clutch to be engaged fully.

NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.

THROTTLE B PRESSUREProCarManuals.com

Description

Lock-up System (cont'd)

Deceleration Lock-up

Torque Converter Clutch (Lock-up Control) Solenoid Valve A: ON Torque Converter Clutch (Lock-up Control) Solenoid

Valve B: Duty Operation

The PCM switches solenoid valve B on and off rapidly under certain conditions. The slight lock-up and half lock-up regions

are maintained so as to lock the torque converter properly.

NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.ProCarManuals.com

Park Mechanism

The park mechanism locks the transmission by engaging the park pawl with the park gear which is splined to the counter-

shaft.

Shifting to [3 position causes the park cone (installed at the end of the park rod) to press the park pawl onto the park gear.

Even if the end of the park pawl rides on top of the park gear teeth, slight movement of the countershaft will cause the

park pawl and the park gear to mesh with each other completely because the park cone receives tension from the park rod

spring. The park pawl receives the tension (which acts to separate the park pawl from the park gear) from the park pawl

spring.

COUNTERSHAFT

PARK ROD SPRING

PARK PAWL
PARK GEAR

PARK ROD HOLDER

PARK CONEProCarManuals.com

Component Locations

POWERTRAIN CONTROL

MODULE (PCM)

SHIFT LOCK

SOLENOID

PARK PIN

SWITCH

COUNTERSHAFT

SPEED SENSOR

TORQUE CONVERTER CLUTCH

(LOCK-UP CONTROL)

SOLENOID VALVES A AND B
MAINSHAFT SPEED SENSOR

SHIFT SOLENOID

VALVES A AND B

(Located in transmission.)

VEHICLE SPEED

SENSOR (VSS)

A/T CLUTCH PRESSURE

CONTROL SOLENOID VALVE

(Located in transmission.)
TRANSMISSION

RANGE SWITCH

A/T GEAR POSITION

SWITCHProCarManuals.com