1996 ACURA RL KA9 lock

Electronic Control System

The electronic control system consists of a Powertrain Control Module (PCM), sensors, a A/T clutch pressure control

solenoid and four solenoid valves. Shifting and lock-up are electronically controlled for comfortable driving under all con-

ditions. The PCM is located below the dashboard, under the front lower panel on the passenger's side.

PCM

Throttle Position Sensor

Signal

Engine Coolant Temperature

Sensor Signal

Indicator Light

Self-Diagnosis Signal
PGM-FI

Control System

Shift Control

Lock-up Control

A/T Control System

Self-Diagnosis

Function
Vehicle Speed Sensor

Signal

Service Check Connector

Shift Solenoid

Valve A

Shift Solenoid

Valve B

A/T Clutch Pressure Control

Solenoid Valve

Torque Converter Clutch

(Lock-up Control)

Solenoid Valve A

Torque Converter Clutch

(Lock-up Control)

Solenoid Valve B

Mainshaft Speed Sensor

Signal

Countershaft Speed

Sensor Signal
Interlock SystemProCarManuals.com

Description
Electronic Contro l Syste m (cont'd )
Shift Contro l
Th e PC M instantl y determine s whic h gea r shoul d b e selecte d b y variou s signal s sen t fro m sensors , an d i t actuate s th e
shif t solenoi d valve s A an d B to contro l shifting . Also , a Grad e Logi c Contro l Syste m control s shiftin g i n positio n whil e
th e vehicl e is ascendin g o r descendin g a slope , o r reducin g speed .
* : Se e pag e 14-3 6 fo r revers e inhibito r contro l description .
Lock-u p Contro l
Fro m senso r inpu t signals , th e PC M determine s whethe r t o tur n th e lock-u p O N o r OF F an d activate s torqu e converte r
clutc h (lock-u p control ) solenoi d valv e A and/o r B accordingly . Th e combinatio n o f drivin g signal s t o torqu e converte r
clutc h (lock-u p control ) solenoi d valve s A an d B is show n in th e tabl e below .
ProCarManuals.com

Description

Electronic Control System (cont'd)

Ascending Control

When the PCM determines that the vehicle is climbing a hill in position, the system extends the engagement area of

3rd gear to prevent the transmission from frequently shifting between 3rd and 4th gears, so the vehicle can run smooth

and have more power when needed.

NOTE:

• Shift schedules between 3rd and 4th gear stored in the PCM enable the PCM's fuzzy logic to automatically select the

most suitable gear according to the magnitude of a gradient.

• Fuzzy logic is a form of artificial intelligence that lets computers respond to changing conditions much like a human

mind would.

Descending Control

When the PCM determines that the vehicle is going down a hill in position, the shift-up speed from 3rd to 4th gear

when the throttle is closed becomes faster than the set speed for flat road driving to widen the 3rd gear driving area.

This, in combination with engine braking from the deceleration lock-up, achieves smooth driving when the vehicle is

descending. There are two descending modes with different downshift (4-3) schedules according to the magnitude of a

gradient stored in the PCM. When the vehicle is in 4th gear, and you are decelerating on a gradual hill, or when you are

applying the brakes on a steep hill, the transmission will downshift to 3rd gear. When you accelerate, the transmission will

then return to 4th gear.

ASCENDING MODE

DESCENDING MODE

3RD/4TH SHIFTING

CHARACTERISTICS

CONTROL AREA
Flat road

mode

Steep descending

mode

Gradual descending

modeProCarManuals.com

Description

The hydraulic control system is controlled by the ATF pump, valves and accumulators in the valve bodies. The ATF pump

is driven by splines on the end of the torque converter which is attached to the engine.

Fluid from the ATF pump flows through the regulator valve to maintain specified pressure through the main valve body to

the manual valve, directing pressure to each of the clutches.

The valve body includes the main valve body, the secondary valve body, the ATF pump body, the regulator valve body,

the throttle valve body, and the accumulator body. The throttle valve body is joined with the A/T clutch pressure control

solenoid valve.

The shift solenoid valves A and B are bolted on the secondary valve body. The torque converter clutch (lock-up control)

solenoid valves A and B are bolted on the outside of the torque converter housing.

ATF PUMP BODY

ACCUMULATOR BODY

SHIFT SOLENOID

VALVE B

SHIFT SOLENOID

VALVE A

REAR COVER

REGULATOR VALVE

BODY

THROTTLE VALVE BODY

SECONDARY VALVE BODY

ATF PASSAGE
MAIN VALVE BODY
Hydraulic ControlProCarManuals.com

Hydraulic Control (cont'd)

ATF Pump Body

The ATF pump body is located on the torque converter housing. The ATF pump body consists of the ATF pump gears, the

relief valve, the lock-up control valve, the lock-up timing valve and the torque converter check valve. The torque converter

check valve is located between the ATF pump body and the torque converter housing.

Accumulator Body

The accumulator body is located on the torque converter housing next to the ATF pump body. The accumulator body

houses the 3rd accumulator piston and the 4th accumulator piston.

Regulator Valve Body

The regulator valve body is located on the ATF pump body. The regulator valve body consists of the regulator valve, the

cooler relief valve and the lock-up shift valve.

REGULATOR VALVE

BODY

REGULATOR VALVE

4TH ACCUMULATOR

3RD ACCUMULATOR
ATF PUMP BODY

RELIEF VALVE

LOCK-UP CONTROL

VALVE

LOCK-UP TIMING

VALVE

TORQUE CONVERTER

CHECK VALVE

COOLER RELIEF

VALVE

ACCUMULATOR BODY
LOCK-UP SHIFT

VALVE
DescriptionProCarManuals.com

Description
Hydraulic Flo w
Genera l Char t o f Hydrauli c Pressur e
Line Pressur e Modulato
r Pressur e
Throttl e B Pressur e
Clutc h Pressur e
Lin e Pressur e Contro l Pressur e
Torqu e Converte r Pressur e
Lubricatio n Pressur e
Distributio n o f Hydrauli c Pressur e
Regulato r Valv e
Manua l Valv e - Torqu
e Converte r Pressur e
• Lubricatio n Pressur e
T o Regulat e Lin e Pressur e
Modulato r Valv e
To Selec t Lin e Pressur e
Clutc h Pressur e Clutc
h Pressur e
Shift Solenoi d Valve s
Torque Converte r Clutc h (Lock-u p Control )
Solenoi d Valve s
Regulato r Valv e
Throttl e B Pressur e
Line Pressur e Contro l Pressur e
Lin e Pressur e Contro l Valv e
Throttl e Valv e
1-2 Shif t Valv e
2- 3 Shif t Valv e
3- 4 Shif t Valv e
Modulato r Pressur e
ATF Pum p Regulator Valv e
ProCarManuals.com

Position

As the engine turns, the ATF pump also starts to operate. Automatic transmission fluid (ATF) is drawn from (99) and dis-

charged into (1). Then, ATF flowing from the ATF pump becomes the line pressure (1). The line pressure (1) is regulated

by the regulator valve. The torque converter inlet pressure (92) enters (94) of the torque converter through the lock-up

shift valve and discharges into (90). The torque converter check valve prevents the torque converter pressure from rising.

Under this condition, the hydraulic pressure is not applied to the clutches as the manual valve stops line pressure (1).

NOTE:

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

• The hydraulic circuit is for '96 - '98 models. On '99 - 01 models, the 2nd accumulator is different.ProCarManuals.com

Lock-up System

Lock-up Clutch

1. Operation (clutch on)

With the lock-up clutch on, the fluid in the chamber between the torque converter cover and the lock-up piston is drained

off, and the converter fluid exerts pressure through the piston against the torque converter cover. As a result, the converter

turbine is locked to the converter cover. The effect is to bypass the converter, thereby placing the vehicle in direct drive.

LOCK-UP PISTON

TORQUE CONVERTER

COVER
DAMPER SPRING

TURBINE

2. Operation (clutch off)

With the lock-up clutch off, the fluid flows in the reverse of CLUTCH ON. As a result, the lock-up piston moves away from

the converter cover, and the torque converter lock-up is released.

TORQUE CONVERTER

COVER
MAINSHAFT
DescriptionProCarManuals.com