engine coolant ACURA TL 1995 Service Owner's Manual

PGM-FI System

System Description

INPUTS
ENGINE CONTROL MODULE (ECM)

OUTPUTS

Fuel Injectors

PGM-FI Main Relay (Fuel Pump)

MIL

IAC Valve

A/C Compressor Clutch Relay

Radiator Fan Relay

Condenser Fan Relay

ALT

ICM

EVAP Purge Control Solenoid

Valve

Primary HO2S Heater

Secondary H02S Heater

EGR Control Solenoid Valve

IAB Control Solenoid Valve

EVAP Bypass Solenoid Valve*2

EVAP Control Canister Vent Shut

Valve*2

*1: '95-96 models

*2: '97 - 98 models

PGM-FI System

The PGM-FI system on this model is a sequential multiport fuel injection system.

Fuel injector Timing and Duration

The ECM contains memories for the basic discharge durations at various engine speeds and manifold air flow rates. The

basic discharge duration, after being read out from the memory, is further modified by signals sent from various sensors

to obtain the final discharge duration.

Idle Air Control

Idle Air Control Valve (IAC Valve)

When the engine is cold, the A/C compressor is on, the transmission is in gear, the brake pedal is depressed, the P/S load

is high, or the alternator is charging, the ECM controls current to the IAC Valve to maintain the correct idle speed.

Ignition Timing Control

• The ECM contains memories for basic ignition timing at various engine speeds and manifold air flow rates. Ignition

timing is also adjusted for engine coolant temperature.

• A knock control system is also used. When detonation is detected by a knock sensor (KS), the ignition timing is retarded.

Other Control Functions

1. Starting Control

When the engine is started, the ECM provides a rich mixture by increasing fuel injector duration.

2. Fuel Pump Control

• When the ignition switch is initially turned on, the ECM supplies ground to the PGM-FI main relay that supplies

current to the fuel pump for two seconds to pressurize the fuel system.

• When the engine is running, the ECM supplies ground to the PGM-FI main relay that supplies current to the fuel pump.

• When the engine is not running and the ignition is on, the ECM cuts ground to the PGM-FI main relay which cuts

current to the fuel pump.

3. Fuel Cut-off Control

• During deceleration with the throttle valve closed, current to the fuel injectors is cut off to improve fuel economy at

speeds over 1,250 rpm.

• Fuel cut-off action also takes place when engine speed exceeds 7,100 rpm, regardless of the position of the throttle

valve, to protect the engine from over-revving.
CKP/TDC/CYP Sensor

CKF Sensor

MAF Sensor

ECT Sensor

IAT Sensor

TP Sensor

EGR Valve Lift Sensor

Primary HO2S

Secondary H02S

VSS

BARO Sensor

ELD

Front KS

Rear KS

Starter Signal

ALT FR Signal

Air Conditioning Signal

A/T Gear Position Signal

Battery Voltage (IGN.1)

Brake Switch Signal

PSP Switch Signal

EVAP Purge Flow Switch*1

Fuel Tank Pressure Sensor*2ProCarManuals.com

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

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

From

PGM-FI

MAIN

RELAY

INTAKE

MANIFOLD
VARIOUS SENSORS

FAST

IDLE

THERMO

VALVE
IDLE

ADJUSTING

SCREW
ENGINE

COOLANT
ENGINE

COOLANT

IAC VALVE
ECMProCarManuals.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 CONTROL

SOLENOID VALVE

IAB

CHECK

VALVE

IAB

CONTROL

DIAPHRAGM
From No. 4 ECU

(ECM) ('95 - 96 models: 15A,

'97-98 models: 20A)

FUSE

(in the under-dash

fuse/relay box)

From PGM-FI

MAIN RELAY

VARIOUS

SENSORS

IAB

VACUUM TANK

THROTTLE
BODY

INTAKE

AIR DUCT

ACL

INTAKE

MANIFOLD
IDLE

ADJUSTING

SCREW
FAST

IDLE

THERMO

VALVE

RESONATOR
INTAKE

AIR

PIPE
IAC VALVE

ENGINE

COOLANT
ENGINE

COOLANT

IAB

VALVE
ECMProCarManuals.com

Emission Control System

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.

'95 - 96 models:

EVAP PURGE CONTROL SOLENOID VALVE OFF AFTER

STARTING ENGINE

'97 - 98 models:

EVAP PURGE CONTROL SOLENOID VALVE DUTY CON-

TROLLED AFTER STARTING ENGINE

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.
ENGINE COOLANT TEMPERATURE ABOVE 167°F (75°C)

ENGINE COOLANT TEMPERATURE ABOVE 158°F (70°C)ProCarManuals.com

Description

The electronic control system consists of the Transmission Control Module (TCM), sensors, a linear solenoid, and four

solenoid valves.

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

The TCM is located below the dashboard, behind the glove box on the passenger's side.

TCM

Linear Solenoid

Shift Control

Solenoid Valve A

Shift Control

Solenoid Valve B

Lock-up Control

Solenoid Valve A

Lock-up Control

Solenoid Valve B

Engine Speed Signal

Brake Switch Signal

Mainshaft Speed Sensor

Signal

Countershaft Speed

Sensor Signal

Vehicle Speed Sensor

Signal

Indicator Light

Self-Diagnosis Signal
Electronic Control System

Shift Control

Lock-up Control
Throttle Position

Sensor Signal

Engine Coolant

Temperature

Sensor Signal

Service Check

Connector

Barometric

Pressure Sensor

INTERLOCK

CONTROL UNIT

Self-Diagnosis

FunctionProCarManuals.com

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

Component Locations

BRAKE SWITCH

TRANSMISSION CONTROL

MODULE (TCM)

ENGINE CONTROL

MODULE (ECM)

THROTTLE POSITION (TP)

SENSOR

ENGINE COOLANT

TEMPERATURE (ECT)

SENSOR
LOCK-UP CONTROL SOLENOID

VALVE ASSEMBLY

MAINSHAFT SPEED SENSOR

COUNTERSHAFT SPEED

SENSOR

VEHICLE SPEED

SENSOR (VSS)
AUTOMATIC TRANSAXLE (A/T)

GEAR POSITION SWITCH

SHIFT CONTROL SOLENOID

VALVE ASSEMBLY*

LINEAR SOLENOID*

*: Located in transmission.ProCarManuals.com

Troubleshooting

Radiator Fan Control Module Input Tests

NOTE: Perform the following tests with the radiator fan control module 8P connector connected, the ignition switch ON (II),

and the A/C switch OFF. If you find the cause of a problem, correct it before you continue.

RADIATOR FAN CONTROL MODULE 8P CONNECTOR

WIRE SIDE OF FEMALE TERMINALS

Terminal

No.

4

6

7

2

3

1

8

5
Wire

color

BLK

WHT/GRN

BLK/YEL

YEL/BLK

YEL/WHT

YEL

LT

GRN/YEL

WHT/GRN
Test condition

Check for voltage to body

ground.

Check for battery voltage:

Check for battery voltage:

Ignition switch - ON (II)

Check for battery voltage:

Ignition switch - ON (II)

Check for battery voltage:

Ignition switch - ON (II)

Check for battery voltage:

Ignition switch - ON (II)

Connect to body ground:

Ignition switch - ON (II)

Check for voltage.
Desired results

There should be less

than one volt.

There should be battery

voltage.

Condenser fan and radia-

tor fan should come on.

Approx. 11 V (engine

coolant temperature

below 207°F [97°C])
Corrective action if desired results are

not obtained

Repair open to body ground.

Check No. 39 (10 A) fuse in the under-

hood fuse/relay box; if OK, repair open

in the WHT/GRN wire.

Check No. 4* fuse in the under-dash

fuse/relay box; if OK, repair open in the

BLK/YEL wire.

Check No. 8 (7.5 A) fuse in the under-

dash fuse/relay box; if OK, repair open in

the YEL/BLK wire.

Replace the radiator fan control module.

Before you connect the new radiator fan

control module, disconnect both fan

relays. Check for continuity between the

YEL/WHT (or YEL) wire and ground, using

the 20 k scale on your ohmmeter. There

should be no continuity. If there is conti-

nuity, the new radiator fan control mod-

ule will be damaged when you connect it.

Check for an open in the LT GRN/YEL

wire between the radiator fan control

module and the condenser fan relay or

the radiator fan relay. If OK, check for an

open in the YEL/WHT wire between the

radiator fan control module and the con-

denser fan relay, or the YEL wire between

the radiator fan control module and the

radiator fan relay. If OK, test the con-

denser fan relay or the radiator fan relay.

Faulty engine coolant temperature (ECT)

switch B, short to body ground, or faulty

radiator fan control module.

* No.4 (15 A): '95 and '96 models

No.4 (20 A): '97 and '98 modelsProCarManuals.com

Ignition Syste m
Descriptio n
Ignition Timin g Control :
Th e programme d ignitio n (PGM-IG ) use d i n thi s engin e provide s optimu m contro l o f ignitio n timing . A microcompute r
determine s th e timin g i n respons e t o engin e spee d an d intak e ai r flo w mass . Th e inpu t signal s ar e transmitte d b y th e
TDC/CKP/CY P sensor , throttl e positio n (TP ) sensor , engine coolant temperatur e (ECT ) sensor , an d MA F sensor . Thi s sys -
tem , whic h i s no t dependen t o n a governo r o r vacuu m diaphragm , i s capabl e o f settin g lea d angle s wit h complicate d char -
acteristic s whic h canno t b e provide d b y conventiona l governor s o r diaphragms .
Basi c Control :
The contro l uni t ha s store d withi n it th e optimu m basi c ignitio n timin g fo r operatin g condition s base d upo n engin e spee d
and intak e ai r flo w mass . Wit h compensatin g signal s fro m sensors , th e syste m determine s optimu m ignitio n timin g an d
duratio n fo r ambien t condition s an d send s voltag e pulse s t o th e ICM .
Compensatio n of ignitio n timing :
Compensatio n Ite m
Idlin g
Compensatio n a t warm-u p
ECT compensatio n Relate
d Senso r an d Informatio n
TDC/CKP/CY P senso r
MAF senso r
ECT senso r
ECT senso r
Descriptio n
Ignition timin g i s controlle d t o th e targe t spee d
wit h compensatio n accordin g t o th e idlin g speed .
La g angl e is adjuste d accordin g t o warm-u p con -
dition s t o brin g abou t a goo d balanc e betwee n
operating performanc e an d exhaus t ga s level .
Compensatio n fo r lea d angl e a t lo w engin e
coolan t temperatur e an d la g angl e a t hig h engin e
coolan t temperature .
Control a t Start :
Ignitio n timin g is fixe d a t 5 ° BTD C fo r cranking . Th e crankin g is detecte d b y th e TD C senso r (crankin g rpm ) an d starte r signal .
ProCarManuals.com

Charging System

Description

To improve fuel economy, the alternator control system within the ECM changes the voltage generated at the alternator in

accordance with driving conditions.

Throttle position (TP) sensor

Engine coolant temperature

(ECT) sensor

Intake air temperature (IAT)

sensor

TDC/CKP/CYP sensor

Vehicle speed sensor (VSS)

ELD

Air conditioning signal
ECM

Alternator

STARTER SWITCH ON
Generated voltage decreases from 14.0 V to 12.5 V

AND

ELECTRICAL LOAD below 15 A

and

VEHICLE SPEED between 9 mph (15 km/h) and

44 mph (70
km/h)

and

ENGINE SPEED between 1,100 rpm and 3,000 rpm

and

ENGINE COOLANT TEMPERATURE above 176°F

(80°C)

and

A/C SWITCH OFF

and

INTAKE AIR TEMPERATURE above 65°F (18°C)
AND

FUEL CUT-OFF CON-

TROL function is not

engaged.ProCarManuals.com