1995 ACURA TL Service Repair Manual

Description

GRADE LOGIC CONTROL SYSTEM

How it works:

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

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

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

reducing speed.

SENSORS

SIGNALS DETECTED

TCM
Electronic Control System (cont'd)ProCarManuals.com

Ascending Control

When the TCM 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 TCM enable the TCM'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 TCM 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 ascending modes with different 3rd gear driving areas according to the magnitude of a gradient stored in

the
TCM.

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

• Deceleration Control

When the vehicle goes around a corner, and needs to decelerate first and then accelerate, the TCM sets the data for deceleration

control to reduce the number of times the transmission shifts. When the vehicle is decelerating from speeds above 30 mph

(48 km/h), the TCM shifts the transmission from 4th to 2nd earlier than normal to cope with upcoming acceleration.ProCarManuals.com

Hydraulic Control
The hydrauli c contro l syste m is controlle d b y th e AT F pump , valve s an d accumulator s i n th e valv e bodies . Th e AT F pum p
i s drive n b y spline s o n th e en d o f th e torqu e converte r whic h i s attache d t o th e engine .
Flui d fro m th e AT F pum p flow s throug h th e regulato r valv e t o maintai n specifie d pressur e throug h th e mai n valv e bod y t o
th e manua l valve , directin g pressur e t o eac h o f th e clutches .
Th e valv e bod y include s th e mai n valv e body , th e serv o body , th e AT F pum p body , th e regulato r valv e body , th e throttl e
valv e body , an d th e 2n d accumulato r body .
Th e throttl e valv e bod y i s joine d wit h th e linea r solenoid . Th e throttl e valv e body/linea r solenoi d assembl y i s bolte d o n th e
2n d accumulato r body .
Th e shif t contro l solenoi d valv e assembl y i s bolte d o n th e serv o body . Th e lock-u p contro l solenoi d valv e assembl y i s bolte d
o n th e outsid e o f th e torqu e converte r housing .
LOCK-UP CONTRO LSOLENOI D VALV E
ASSEMBL Y
REGULATO RVALVE BOD Y
SHIF T CONTRO L
SOLENOI D VALV E
ASSEMBL Y
REA R COVE R
ATF PUM PBODY
TORQU E CONVERTE RHOUSING
THROTTL E VALV EBODY
2ND ACCUMULATO RBODYMAIN VALV E BOD YCOVE RMAIN VALV EBODY
SERV O BOD Y
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Description
Rear Cove r
The rea r cove r house s th e 1s t accumulator , th e 1st-hol d accumulator , an d th e AT F fee d pipes .
Lowe r Valv e Bod y Assembl y
Th e lowe r valv e bod y assembl y i s locate d o n th e botto m o f th e transmission . Th e lowe r valv e bod y assembl y consist s o f
the mai n valv e body , th e serv o body , shif t contro l solenoi d valve s A/ B an d th e AT F strainer .
Servo Bod y
Th e serv o bod y i s locate d o n th e mai n valv e body . Th e serv o valv e i s integrate d wit h th e shif t for k shaft , th e 3r d accumu -
lato r an d th e 4t h accumulator , whic h ar e al l assemble d in th e serv o body .
Th e shif t for k installe d o n th e en d o f th e shif t for k shaf t operate s th e revers e selector .
1ST ACCUMULATO R
1ST-HOLD ACCUMULATO R
REAR COVE R
LOWER VALV E
BOD Y ASSEMBL Y
SHIF T FOR K
SHAF T
SERV O VALV E
Hydrauli c Contro l (cont'd )
4TH ACCUMULATO R
3RD ACCUMULATO R
SERVOBODY
SHIFT FOR K
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Main Valve Body

The main valve body houses the manual valve, the 1-2 shift valve, the 2-3 shift valve, the 3-4 shift valve, the main orifice

control valve, the 2-3 orifice control valve, the 3-4 orifice control valve, the 4th kick-down valve, the 4th exhaust valve, and

the servo control valve.

The primary functions of the main valve body are to switch fluid pressure on and off and to control the hydraulic pressure

going to the hydraulic control system.

MAIN ORIFICE CONTROL VALVE

1-2 SHIFT VALVE

MANUAL VALVE

2-3 SHIFT VALVE

3-4 SHIFT VALVE

2-3 ORIFICE CONTROL VALVE

MAIN VALVE BODY
SERVO CONTROL VALVE

4TH EXHAUST VALVE

4TH KICK-DOWN VALVE

3-4 ORIFICE CONTROL VALVEProCarManuals.com

Description

Regulator Valve Body

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

lock-up shift valve, and the cooler relief valve.

REGULATOR VALVE

BODY

REGULATOR VALVE

LOCK-UP SHIFT

VALVE

COOLER RELIEF

VALVE
STATOR SHAFT ARM
Hydraulic Control (cont'd)ProCarManuals.com

Regulator Valv e
The regulato r valv e maintain s a constan t hydrauli c pressur e fro m th e AT F pum p t o th e hydrauli c contro l system , whil e
als o furnishin g flui d to th e lubricatin g syste m an d torqu e converter .
The flui d fro m th e AT F pum p flow s throug h B an d B' . Th e regulato r valv e ha s a valv e orifice . Th e flui d enterin g fro m B
flow s throug h th e orific e to th e A cavity . Thi s pressur e o f th e A cavit y pushe s th e regulato r valv e to th e righ t side , an d thi s
movemen t o f th e regulato r valv e uncover s th e flui d por t t o th e torqu e converte r an d th e relie f valve . Th e flui d flow s ou t t o
th e torqu e converter , an d th e relie f valv e an d regulato r valv e move s t o th e lef t side .
Accordin g to th e leve l o f th e hydrauli c pressur e throug h B , th e positio n o f th e regulato r valv e change s an d th e amoun t o f
th e flui d fro m B ' throug h D an d C als o changes . Thi s operatio n is continued , maintainin g th e lin e pressure .
(ENGINE NO T RUNNING )(ENGINE RUNNING )
To TORQU E CONVERTE R
To RELIE F VALU EFrom AT F PUM P
Stato r Reactio n hydrauli c Pressur e Contro l
Hydrauli c pressur e increase s accordin g t o th e torqu e is performe d b y th e regulato r valv e usin g th e stato r torqu e reaction .
Th e stato r shaf t i s spline d wit h th e stato r i n th e torqu e converter , an d it s ar m en d contact s th e regulato r sprin g cap . Whe n
th e vehicl e is acceleratin g o r climbin g (Torqu e Converte r Range) , th e stato r torqu e reactio n act s o n th e stato r shaft , an d
the stato r ar m pushe s th e regulato r sprin g ca p in th e directio n in proportio n t o th e reaction . Th e stato r reactio n sprin g
compresses , an d th e regulato r valv e move s t o increas e th e lin e pressur e whic h i s regulate d b y th e regulato r valve . Th e
lin e pressur e reache s it s maximu m whe n th e stato r torqu e reactio n reache s it s maximum .
REGULATO R SPRIN G CA P
STATO R REACTIO N SPRIN G
REGULATO R VALV E
REGULATO R VALV E BOD Y
TORQU E CONVERTE R
STATOR(Inside torqu e converter )
STATOR SHAF TSTATO R SHAF T AR M
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Description

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

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

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

Throttle Valve Body/Linear Solenoid

The throttle valve body is joined with the linear solenoid which is controlled by the TCM. The throttle valve body/linear

solenoid assembly is located on the 2nd accumulator body. The throttle valve body houses the throttle valve.

2nd Accumulator Body

The 2nd accumulator body is located on the torque converter housing beside the ATF pump body. It contains the 2nd

accumulator.

RELIEF VALVE

LOCK-UP CONTROL

VALVE

LOCK-UP TIMING

VALVE

TORQUE CONVERTER

CHECK VALVE
ATF PUMP BODY

ATF PUMP DRIVE GEAR

ATF PUMP DRIVEN GEAR

MODULATOR VALVE

LINEAR SOLENOID

THROTTLE VALVE

2ND ACCUMULATOR

2ND ACCUMULATOR

BODYProCarManuals.com