Actron CP9135 Specifications download pdf (Page 30)

B-1

About OBD II

OBD II

In

1994,

manufacturers

began

equipping

vehicles

with

a

new

class

of

computer

technology

which

puts

more

processing

power

in

the

vehicle

than

ever

before.

It

is

called

On-Board

Diagnostics,

Second

Generation

(OBD

II)

and

offers

increased

system

monitoring

and

diagnostic

information.

Beginning

January 1,

1996,

vehicles

sold

in

the

U.S.

are

required

to

be

OBD

II

compliant.

However,

a

few

vehicles

were

exempt

since

no

changes

were

made

to

the

engine.

Most

domestic

manufacturers

began

using

this

system

on

some

vehicles

beginning

as

early

as

1994.

OBD

II

systems

are

designed

to

meet

or

exceed

standards

and

regulations

to

improve

air

quality.

These

standards

and

regulations

are

primarily

set

forth

by

the

Environmental

Protection

Agency

(EPA)

Clean

Air

Act

of

1990.

Most

of

the

standards

and

regulations

were

developed

by

the

California

Air

Resources

Board

(CARB).

OBD

II

systems

are

unique

in

that

they

possess

the

capability

of

monitoring

the

performance

of

emission

related

systems

and

their

components;

to

detect

hard

and

intermittent

faults

that

may

cause

a

vehicle

to

pollute.

This

new

system

stores

a

large

library

of

general

trouble

codes

along

with

manufacturer-specific

codes,

some

of

which

can

be

accessed

with

the

tool.

These

codes

cover:

Now,

basic

terms

are

standardized

and

all

generic

(global)

codes

share

a

common

format

and

terminology

established

by

the

manufacturers

and

the

Society

of

Automotive

Engineers

(SAE).

Basics of Computer-Controlled Vehicles

This

section

explains

the

engine

computer

control

system,

the

types

of

sensors

and

how

the

computer

controls

engine

fuel

delivery,

idle

speed

and

timing.

Additional

information

may

be

found

in

technical

support

books

at

your

local

library

or

auto

parts

store.

The

more

you

know

about

the

computer

system,

the

better

you

can

diagnose

vehicle

computer

problems.

Computer

controls

were

originally

installed

on

vehicles

to

meet

federal

government

regulations

for

lower

emissions

levels

and

improved

fuel

economy.

This

began

in

the

early

1980’s

when

basic

mechanical

systems

were

no

longer

able

to

accurately

control

key

engine

parameters.

A

computer

could

be

programmed

to

control

the

engine

under

various

operating

conditions,

making

the

engine

more

reliable.

While

these

early

systems

were

very

limited

in

the

scope

of

their

control,

providing

only

10

to

14

trouble

codes,

they

did

help

guide

the

vehicle

repair

process.

Today,

computer

controls

have

made

cars

and

trucks

faster,

cleaner,

and

more

efficient

than

ever

before.

B-Codes . . . . . . . Body Systems

C-Codes . . . . . Chassis Systems

U-Codes . Network Communications

P-Codes . . . . . . Powertrain Systems

A

p

pe

n

d

i

x

B

A

b

o

u

t

O

B

D

I

I

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