1996 ACURA RL KA9 Service Repair Manual

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 .
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Grade Logic Control System

How it works:

The PCM compares actual driving conditions with driving conditions memorized in the PCM, based on the input from the

vehicle speed sensor, throttle position sensor, engine coolant temperature sensor, barometric pressure sensor, brake

pedal position switch signal and shift lever position signal, to control shifting while a vehicle is ascending or descending a

slope.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

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Circuit Diagram and Terminal LocationsProCarManuals.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