sensor ACURA TL 1995 Service Owner's Manual

PGM-FI Syste m
Powertrai n Contro l Modul e (PCM ) (cont'd )
(From pag e 11-55 )
Chec k fo r a shor t i n th e wire s
(VC C lines) :
1 . Tur n th e ignitio n switc h OFF .
2 . Disconnec t th e PC M connec -
tor D (22P) .3. Chec k fo r continuit y betwee nbody groun d an d PC M con -necto r terminal s D1 0 an d D2 1individually .
Is ther e continuity ?
I s ther e batter y voltage ?
Chec k fo r a n ope n i n th e wire s
(L G lines) :
1 . Reconnec t al l senso r connec -
tors .
2 . Reconnec t th e PC M connecto r
D (22P) .3. Tur n th e ignitio n switc h O N (II) .
4 . Measur e voltag e betwee n
bod y groun d an d PC M connec -
to r terminal s A2 6 an d B 9 indi -
vidually .
I s ther e les s tha n 1. 0 V ?
Substitut e a known-goo d PC M
an d recheck . I f symptom/indica -
tio n goe s away , replac e th e origi -
nal PCM .
PCM CONNECTO R D (22P )
Repai r shor t t o bod y groun d
i n th e wir e betwee n PC M
(D10 ) an d MA P sensor .Repair shor t t o bod y groun d in
th e wir e betwee n PC M (D21 )
an d EG R valv e lif t sensor , T P
sensor , TC S contro l valv e
angl e senso r o r fue l tan k pres -
sur e senso r ('9 7 - 9 8 models) .Wir
e sid e o f femal e terminal s
A (26P)
PCM CONNECTOR S
Repair ope n i n th e wire(s )
betwee n PC M (A13 , B1 ) an d
PGM-F I mai n relay .
Chec k fo r poo r connection s
o r loos e wire s a t th e PGM-F I
mai n relay .
Tes t th e PGM-F I mai n rela y
(se e pag e 11-129 ). Wir
e sid e o f femal e terminal s
PCM CONNECTOR S
A (26P)B (16P)
Repai r ope n i n th e wire(s )
betwee n PC M (A26 , B9 ) an d
G10 1 tha t ha d mor e tha n 1. 0 V .Wir e sid e o f femal e terminal s
Check fo r a n ope n i n th e wire s
(IG P lines) :
1 . Tur n th e ignitio n switc h O N (II) .
2 . Measur e voltag e betwee n bod y
groun d an d PC M connecto r
terminal s A1 3 an d B 1 individu -
ally .B (16P )
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Idle Control System

System Description

The idle speed of the engine is controlled by the Idle Air Control (IAC) Valve.

The valve changes the amount of air bypassing into the intake manifold in response to electric current controlled by the

PCM. When the IAC Valve is activated, the valve opens to maintain the proper idle speed.

ENGINE

COOLANT

IAC VALVE

INTAKE

MANIFOLD
PCM
From

PGM-FI

MAIN

RELAY

FAST

IDLE

THERMO

VALVE
IDLE

ADJUSTING

SCREW
VARIOUS

SENSORS

ENGINE

COOLANTProCarManuals.com

Intake Air System

System Description

The system supplies air for all engine needs. It consists of the intake air pipe, Air Cleaner (ACL), intake air duct, Throttle

Body (TB), Idle Air Control (IAC) Valve, fast idle thermo valve, and intake manifold.

A resonator in the intake air pipe provides additional silencing as air is drawn into the system.

IAB LOW

CONTROL

SOLENOID

VALVE
IAB HIGH

CONTROL SOLENOID VALVE

IAB LOW

CONTROL

DIAPHRAGM

VALVE
From PGM-FI

MAIN RELAY

From No. 4 ECU

(PCM)
(15 A)

FUSE

(in the under-dash

fuse/relay box)

VARIOUS

SENSORS

INTAKE

AIR

DUCT

FAST

IDLE

THERMO

VALVE
IDLE

ADJUSTING

SCREW
ENGINE

COOLANT
INTAKE

MANIFOLD
PCM
IAB

VACUUM

TANK
IAB

CHECK

VALVE

IAB HIGH

CONTROL

DIAPHRAGM

VALVEProCarManuals.com

Emission Contro l Syste m
Three Wa y Catalyti c Converte r (TWC )
Descriptio n
The Thre e Wa y Catalyti c Converte r (TWC ) i s use d t o conver t hydrocarbon s (HC) , carbo n monoxid e (CO) , an d oxide s o f
nitroge n (NOx ) i n th e exhaus t ga s to carbo n dioxid e (CO
2), dinitroge n (N2) an d wate r vapor .
SECONDAR Y HEATE D OXYGEN SENSOR (SENSO R 2 )
HOUSIN G
THREE WA YCATALYST SFRONT O F
VEHICL E
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Emission Control System

Exhaust Gas Recirculation (EGR) System

Description

The EGR system is designed to reduce oxides of nitrogen emissions (NOx) by recirculating exhaust gas through the EGR

valve and the intake manifold into the combustion chambers. It is composed of the EGR valve, EGR vacuum control valve,

EGR control solenoid valve, PCM and various sensors.

The PCM contains memories for ideal EGR valve lifts for varying operating conditions. The EGR valve lift sensor detects

the amount of EGR valve lift and sends the information to the PCM. The PCM then compares it with the ideal EGR valve lift

which is determined by signals sent from the other sensors. If there is any difference between the two, the PCM cuts cur-

rent to the EGR control solenoid valve to reduce vacuum applied to the EGR valve.

EGR VALVE

LIFT SENSOR
INTAKE

MANIFOLD

From No. 4 ECU (PCM)

FUSE (15 A) or (20 A)

(in the under-dash

fuse/relay box)

EGR

CONTROL

SOLENOID

VALVE

EGR

VACUUM

CONTROL

VALVE
VARIOUS

SENSORS
EGR VALVEProCarManuals.com

Evaporative Emission (EVAP) Controls

Description

The evaporative emission controls are designed to minimize the amount of fuel vapor escaping to the atmosphere. The

system consists of the following components:

A. Evaporative Emission (EVAP) Control Canister

An EVAP control canister is used for the temporary storage of fuel vapor until the fuel vapor can be purged from the

EVAP control canister into the engine and burned.

B. Vapor Purge Control System

EVAP control canister purging is accomplished by drawing fresh air through the EVAP control canister and into a port

on the throttle body. The purging vacuum is controlled by the EVAP purge control solenoid valve.

'96 model:
'97 - 98 models:

C. Fuel Tank Vapor Control System

When fuel vapor pressure in the fuel tank is higher than the set value of the EVAP two way valve, the valve opens and

regulates the flow of fuel vapor to the EVAP control canister.

'96 model:

INTAKE MANIFOLD
THROTTLE

BODY

EVAP PURGE

CONTROL

SOLENOID VALVE

FUEL TANK

EVAP VALVE
EVAP TWO WAY VALVE
From

No. 4 ECU
(PCM) (15A)

FUSE (in the under-dash

fuse/relay box)

EVAP

CONTROL

CANISTER FRESH

AIR
EVAP PURGE

FLOW SWITCH

FUEL FILL CAP
PCM
VARIOUS

SENSORS

FUEL TANK
ENGINE COOLANT TEMPERATURE ABOVE 158°F (70°C)
ENGINE COOLANT TEMPERATURE ABOVE 99°F (37°C)
EVAP PURGE CONTROL SOLENOID VALVE DUTY CON-

TROLLED AFTER STARTING ENGINE
EVAP PURGE CONTROL SOLENOID VALVE OFF AFTER

STARTING ENGINEProCarManuals.com

Emission Contro l Syste m
Evaporativ e Emissio n (EVAP ) Control s (cont'd )
'97 - 9 8 models :
INTAKE
MANIFOL DTHROTTL EBODY
FromNo. 4 EC U (PCM )(20 A ) FUS E
(i n th e under-das h
fuse/rela y box )
EVAP CONTROL CANISTERVENT SHUT VALVE
EVAP TWO WAY VALVE
EVAPCONTROLCANISTER
VARIOU SSENSOR S
EVAP BYPAS SSOLENOI D VALV E
FUEL TAN K
FUE L TAN K
PRESSUR E
SENSO RFUE
L TAN K
EVA P VALV E FUE
L FIL L CA P
PCM
EVA P PURG ECONTRO LSOLENOI D VALV E
EVAP THRE EWAY VALV E
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Description

The automatic transmission is a combination of a 3-element torque converter and a dual-shaft electronically controlled

automatic transmission which provides 4 speeds forward and 1 reverse. The entire unit is positioned in line with the engine.

Torque Converter, Gears and Clutches

The torque converter consists of a pump, turbine, and stator, assembled in a single unit. They are connected to the engine

crankshaft so they turn together as a unit as the engine turns. Around the outside of the drive plate is a ring gear which

meshes with the starter pinion when the engine is being started.

The entire torque converter assembly serves as a flywheel while transmitting power to the transmission mainshaft.

The transmission has two parallel shafts: the mainshaft and the countershaft. The mainshaft is in line with the engine

crankshaft. The mainshaft includes the 1st, 4th and 2nd clutches and gears for 4th, 1st, 2nd and reverse (3rd gear is integral

with the mainshaft). The countershaft includes the 3rd, 1st-hold and reverse clutches, and gears for 3rd, 4th, 1st, 2nd,

reverse and parking. The secondary drive gear is integrated with the countershaft. The gears on the mainshaft are in con-

stant mesh with those on the countershaft. When certain combinations of gears in the transmission are engaged by clutch-

positions.

and
es, power is transmitted from the mainshaft to the countershaft to provide

Electronic Control

The electronic control system consists of a Powertrain Control Module (PCM), sensors, a linear solenoid and four solenoid

valves. Shifting and lock-up are electronically controlled for comfortable driving under all conditions.

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

Hydraulic Control

The lower valve body assembly includes the main valve body, the secondary valve body, the throttle valve body, the lin-

ear solenoid, the shift control solenoid valves and the ATF passage body. They are bolted on the lower part of the trans-

mission housing. The regulator valve body, the ATF pump body, and the accumulator body are bolted to the torque con-

verter housing.

The main valve body on '96 model contains the manual valve, the 1-2 shift valve, the 2-3 shift valve, the 3-4 shift valve, the

4-3 kick-down valve and the Clutch Pressure Control (CPC) valve. The main valve body on '97 model contains the manual

valve, the 1-2 shift valve, the 2-3 shift valve, the 3-4 shift valve, the 4-3 kick-down valve and the main orifice control valve.

The secondary valve body on '96 model contains the 3-4 orifice control valve, the 4-3 shift timing valve, the modulator valve

and the accumulator pistons.The secondary valve body on '97 model contains the 3-4 orifice control valve, the 4-3 shift tim-

ing valve, the line pressure control valve, the modulator valve and the accumulator pistons. The throttle valve body

includes the throttle valve which is bolted onto the secondary valve body. The linear solenoid is joined to the throttle valve

body. The regulator valve body contains the regulator valve, the lock-up shift valve and the cooler relief valve. Fluid from

the regulator passes through the manual valve to the various control valves. The ATF pump body contains the lock-up tim-

ing valve, the lock-up control valve and the relief valve. The torque converter check valve is located in the torque converter

housing under the ATF pump body. The accumulator body contains the accumulator pistons. The reverse accumulator and

the 1st-hold accumulator pistons are assembled in the rear cover.

The 1st, 1st-hold, 2nd and reverse clutches receive fluid from their respective feed pipes, and the 3rd and 4th clutches

receive fluid from the internal hydraulic circuit.

Shift Control Mechanism

Input from various sensors located throughout the vehicle determines which shift control solenoid valve the PCM will acti-

vate. Activating a shift control solenoid valve changes modulator pressure, causing a shift valve to move. This pressurizes a

line to one of the clutches, engaging the clutch and its corresponding gear.

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

mainshaft rotates at the same speed as the engine crankshaft. Together with hydraulic control, the PCM optimizes the tim-

ing of the lock-up mechanism. The lock-up valves control the range of lock-up according to lock-up control solenoid valves

A and B, and throttle valve. When lock-up control solenoid valves A and B activate, modulator pressure changes. The lock-

up control solenoid valves A and B are mounted on the torque converter housing, and are controlled by the PCM.

(cont'd)
Lock-up Mechanism

In
position, in 2nd, 3rd, and 4th, and
position in 3rd, pressurized fluid is drained from the back of the torque convert-ProCarManuals.com

Electronic Control System

The electronic control system consists of a Powertrain Control Module (PCM), sensors, a linear solenoid and four solenoid

valves. Shifting and lock-up are electronically controlled for comfortable driving under all conditions.

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

Description
Electronic Contro l Syste m (cont'd )
Lock-up Contro l
From 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 OFF , an d activate s lock-u p contro l
solenoi d valv e A and/o r B accordingly .
Th e combinatio n o f drivin g signal s t o lock-u p contro l solenoi d valve s A an d B is show n in th e tabl e below .
Shif
t Contro l
Th e PC M
instantaneously 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 contro l solenoi d valve s A an d B to contro l shifting . Also , a Grad e Logi c Contro l Syste m ha s bee n adopte d to contro l
shifting in positio n whil e th e vehicl e is ascendin g o r descendin g a slope , o r reducin g speed .
Shif t contro l solenoi d valv e
Positio n (gear )
(1st)
A
OFF
(2nd )
(3rd)
(4th)
(2nd )
(1st)
(Reverse )
ON
O N
OF F
ON
OF F
ON
B
O N
O N
OF F
OF F
ON
O N
OF F
Dut y operatio n
ONOF FON
O N
AB
OF F
OF F
ON
O N
OF F
ON
ON
Lock-u p contro l solenoi d valv e
Lock-u p conditio n
Lock-u p OF F
Lock-up , sligh t
Lock-up , hal f
Lock-up , ful l
Lock-u p
during deceleratio n
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