84
Idle Speed Con-
trol (ISC)
Maintains proper idle speed
when engine loading changes.
Idle Switch
Signals the ECU when the
throttle is in the closed (idle)
position.
Idle-Up Solenoid
The Idle-Up solenoid assists
the AAC or FICD when the
engine is under heavy load. It
controls idle speed by adjusting
throttle bypass air.
Ignition Coil
A transformer designed to
boost the battery voltage to the
high voltage required to cause
a spark and ignite the air/fuel
mix in the engine’s cylinder.
Igniter unit
The Igniter is an electronic
switch which energizes the
ignition coil. The Igniter is
controlled by the ECU or pick
up coil.
IIA
See Integrated Ignition
Assembly.
IMA
See Idle Mixture Adjuster.
Inhibitor Switch
This switch is located on the
Automatic transmission/
transaxle. It signals the ECU
when the gearshift lever is in
the Neutral or Park position.
Inputs
Electrical signals running into
the ECU. These signals come
from sensors, switches or other
electronic modules. They give
the ECU information about
vehicle operation.
Intake Air control
Valve (IACV)
Controls the amount of intake
air flowing into the intake
manifold.
Intake Air
Temperature
Sensor
This sensor is a thermistor - a
resistor whose resistance
changes with temperature. The
hotter the sensor gets, the lower
the resistance becomes. The
sensor is located along the path
of air entering the engine. The
ECU uses intake air temperature
to provide the proper air/fuel
mixture for the desired engine
operating condition.
Intake Control
System
The Engine Control computer
uses the Intake Control system
to select one of two air paths in
the intake manifold. The proper
air path is based on operating
conditions. One path provides
high engine torque at low
RPM’s while the other path
produces high output at high
RPM’s.
Integrated
Ignition Assembly
(IIA)
The Integrated Ignition
Assembly refers to the
distributor containing the
ignition coil and other ignition
components.
Intercooler
Cools the intake air after
compression by the
turbocharger.
Intermittent
Failures
Intermittent failures may cause
the Check Engine (if equipped)
light to illuminate or flicker. The
Check Engine light (if equipped)
will go off when the problem is
no longer sensed. The trouble
code will remain in memory.
Knock Sensor
(KNK)
See Detonation sensor.
LAF
See Linear Air Fuel Ratio
sensor.
LED
Light Emitting Diode. A
semiconductor device which
acts like a miniature light bulb.
When a small voltage is
applied, the LED glows. LED’s
may be red, orange, yellow or
green. They are often used as
indicators or in numeric
displays.
Linear Air/Fuel
Ratio sensor (LAF)
The LAF sensor is similar to an
Oxygen sensor.
Lock-Up Control
solenoid Valve
Controls locking of the torque
converter when signaled by the
ECU. This reduces transmission
slippage and increases fuel
economy.
MAF
See Mass Airflow sensor.
Main Relay
Usually contains two relays.
One for power to the Engine
Control Computer, Fuel
Injectors and the second relay.
The second relay supplies
power to the Fuel pump.
Manifold Absolute
Pressure sensor
(MAP)
This sensor is an electronic
module which sends a signal to
the ECU indicating atmospheric
pressure and/or engine vacuum.
Depending upon sensor type,
the signal may be a dc voltage
or a frequency. More pressure
(less vacuum) makes the
sensor signal increase (higher
voltage or frequency). The ECU
needs to know air pressure both
outside and inside the manifold
to properly adjust air/fuel
mixture and ignition timing for
varying engine load and altitude
conditions.
MAP
See Manifold Absolute
Pressure.
Mass Air Flow
sensor (MAF)
Also referred to as Mass Airflow
Meter, this sensor measures the
amount of air entering the
engine and sends a signal to
the ECU. Depending upon
sensor type, the signal may be
a voltage or frequency. The
signal voltage (or frequency)
increases when the amount of
incoming air goes up. This gives
the ECU information required
for control of fuel delivery, spark
advance and EGR flow.
Summary of Contents for Code Scanner CP9025
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