http://www.goldsswagon.com/Impala SS Dictionary.htm
Special code used on Chevrolet Camaros to indicate that they are
equipped with the racing performance package. This package deletes
air conditioning and several other luxury items and beefs up the
suspension. The 1LE intake elbow is useful for Impala engine
The 6J6 option is two 4" diameter red lights (one left side, one
right side) that face rearward and are mounted inside the car
behind the rear seats and above the rear package shelf (under the
rear window). These come on when you use the brakes or use the
turn signals. They are an option on the 9C1.
Chevrolet order code for the police package option on the Caprice.
This is usually used to refer to parts that only come as part of
this package, such as "9C1 Trunk Mat".
Acronym for Antilock Braking System. This system prevents the
tires from "locking up" under heavy braking or slick conditions by
modulating pressure to the brakes when sensor determine that the
tire is no long rolling. This allow quicker, straighter stops in
most conditions than standard braking.
Abbreviation for the Secondary Air Injection System. This sytem
helps reduce emissions and heats up the catalytic converters more
quickly after startup so exhaust gas conversion can occur sooner.
The enclosure that houses the air filter. Air comes into the "box"
from a small rectangular opening on the front, and is then fed
through the air filter to the top of the box.
The AIR pump pressurized air from the air cleaner and pumps it
back into the check valves near the exhaust manifolds. This is the
key part of the AIR system. The AIR pump is electric and presents
no drag on the engine.
Acronym for assembly line diagnostic link. This is the small black
connector underneath the driver's dash. This connector allows the
dealer to plug in scan tools to test and report the status of the
PCM. This is how the dealer scans for trouble codes. This is also
how the PCM can be reprogrammed.
Another name for the resonators that are on used to quiet the
Impala's air intake.
Acronym used by owners of black Impalas who feel left out because
they don't have a cool acronym like DCM or DGGM to use. Actually,
the official GM name is Standard Onyx Black, but that isn't used
for obvious reasons. Usually taken to mean Bad to the Bone Black.
Acronym for Blue Bow Tie. This is a part from the 97 Cavalier that
will drop into the same place the silver bow tie on the front of
the Impala grill is from the factory. It seems to look better on
the DGGM Impalas than the red bow tie.
Acronym for Brake Transmission Shift Interlock. This is a solenoid
that prevents you from shifting out of park unless your foot is
pressing on the brake pedal. This is touted as a safety feature,
but is commonly thought to be a direct result of the lawsuits
filed by some Audi owners claiming "unintended acceleration" of
their cars when they were started.
Module attached to the exhaust manifold that, when heated, can
convert the harmful emissions of the engine to relatively harmless
gasses. It contains very rare and expensive metals for this
Acronym for Center High Mounted Stop Lamp, which is the third
brake light located at the bottom of the rear window.
A special starting mode that allows for clearing of excess fuel in
the engine. It is made to emulate the method for clearing floods
in carburated cars. The throttle must be depressed to 80% or more.
The PCM will then lean the air/fuel mixture out to 20:1 to clear
the flood. Clear flood mode is automatically shut off when engine
RPM is greater than 300 RPM.
A run mode of the engine when it has warmed up and is using mainly
the oxygen sensor for very accurate monitoring and control of the
air fuel ratio. In this mode, the engine is running very close to
A general classification of mechanisms designed to get cooler air
from outside the engine compartment into the engine intake tract.
This is usually accomplished by some sort of scoop or ducting to
Acronym for Cavalier Red Bow Tie. This bow-tie is a drop-in
replacement for the bow-tie on the grill of the stock Impala.
A 16 pin connector located underneath the instrument panel on the
drivers side. This connector is used to verify correct engine
operation before the engine leaves the assembly plant and also by
technicians to retrieve DTC's stored inside the PCM. This
connector can also be used to flash the PCM with a new program.
Acronym for Dark Cherry Metallic, one of the available colors for
the Impala in 1995 and 1996.
Acronym for Dark Green Grey Metallic, one of the available colors
for the Impala in 1995 and 1996.
A special code stored inside the PCM when a malfunction is
indicated. These codes may be retrieved and examined using some
type of scan tool connected to the DLC. To clear touble codes, the
battery must be disconnected from the PCM. A DTC does not mean
that the engine should be stopped immediately, but that the cause
of the DTC should be checked as soon as possible.
Acronym for Data Link Connector.
Acronym for Daytime Running Lights. This GM option turns the
headlights on at a reduced voltage during all operating
conditions. During nighttime operation, the headlights are
brightened and the rest of the running lights and the tail lights
are also turned on. This option is required in Canada, but can be
fitted to US models. This option is technically not compatible
with the Twilight Sentinel, but you do get the basic twilight
sentinal functionality. The front lamps just don't go off during
daylight hours. On pre-1996 cars, the light sensor was not
included with the package, so the tail lights had to be turned on
manually at dusk.
Acronym for Diagnostic Trouble Code.
Acronym for Engine Coolant Temperature. This sensor is mounted in
the coolant pump and sends engine temperature information to the
PCM. The sensor is a thermistor that changes internal resistance
as the temperature changes. When the resistance is high, the PCM
interprets that the engine is cold. When resistance is low, the
voltage through the wire will decrease and the PCM will interpret
it as a warm engine. The ECT is located on the front of the
engine, just below the water pump.
Acronym for Electronically Erasable Programmable Read Only Memory.
This is more commonly referred to as flash memory. This type of
memory is to store the engine control parameters in the PCM. The
EEPROM in the PCM can be reprogrammed using the Tech-1 scan tool.
Acronym for Exhaust Gas Recirculation. This sytem reduces
emissions, specifically Nitrogen Oxides caused by high combustion
temperatures and excessive oxygen. It does this by decreasing
combusion temperatures and displacing oxygen with spent exhaust
gases. The main element is the EGR valve mounted on the intake
manifold and operated by vacuum.
Abbreviation for the Evaporative Emmisions Control System. This
system utilized a charcoal canister to hold vapors from the fuel
tank while the vehicle is not operating. When the engine is
running, the vapor is purged from the canister into the normal
intake path and consumed in the normal combustion process.
Pipes that can be used in place of the catalytic converters for
export use or off-road use only. These are used where there is no
unleaded fuel available, since leaded fuel would ruin the
First base is a common slang term for the rectangular, black
resonator that is placed between the MAF and the intake elbow.
This resonator rests on top of the radiator. It is called first
base because of its close relationship to the Home Plate resonator
on top of the engine.
Flash memory is a non-volatile form of read-only memory that is
used in the Impala to store the computer program that controls the
engine. It is located in the PCM. On earlier cars, this is known
as "the chip" and is commonly replaced with a higher performance
program stored on a different chip. On LT1 engines, the flash
memory is reprogrammed through the DLC, which is often referred to
as "flashing" the PCM.
This is often the part of the PCM that is referred to as the
"learning" section. There are two parts of fuel trim: short term
and long term. Short term fuel trim is set using the oxygen sensor
inputs to detect a lean or rich condition. The fuel trim is
increase for a lean mixture decreased for a rich mixture. Over a
period of time, if the mixture is continously rich or lean, this
is learned into the long term trim, and the short term is returned
closer to a more ideal position. Short term trim is frozen at the
ideal value during power enrichment to remove the rich condition
that results there from long term memory.
Acronym for Green Grey Metallic, one of the available colors for
the Impala in 1995 and 1996. More commonly referred to as DGGM,
for Dark Green Grey Metallic, but GGM puts it into the TLA (Three
Letter Acronym) territory.
Acronym for Heated Oxygen Sensor. The LT1 uses heated oxygen
sensors to determine if the engine is running lean or rich.
A slang term invented for the triangular resonator that sits on
top of the engine to reduce the noise level of the intake air
path. It is so named for its resemblance to a common home plate
shape in baseball.
Acronym for the Hypertech Power Programmer. This device reprograms
your PCM with a custom performance program. You insert it through
the ALDL underneath you dash. It then reads the stock program out,
modifies it according to your parameters, and stores it back. You
can reprogram and deprogram your PCM at will.
Another name for the Hypertech Power Programmer Plus.
Acronym for the Hypertech Power Programmer Plus. This device works
much the same way as the HPP, but allows more parameters to be
modified, and will eventually allow custom cartridges to be
inserted to function as scan tools and other functions. This is
the second generation of the HPP.
Acronym for the Heating, Ventilation, and Air Conditioning system
Acronym for the Idle Air Control valve.
Acronym for Incoming Air Temperature. This sensor is mounted in
the elbow that connects to the throttle body and monitored by the
PCM. The PCM controls fuel delivery and spark timing based upon
the incoming air density.
The purpose of the Idle Air Control valve is to control engine
idle speed to prevent stalls based upon changes in engine load.
The IAC control is mounted in the throttle body and can bypass air
around it based upon PCM control.
Acronym for In My Humble Opinion. Used in internet e-mail
correspondence to distinguish fact from opinion.
Acronym for Jet Assisted Take Off. The military uses JATO rockets
to assist in getting heavy planes off of the ground. There is an
urban legend about someone who strapped one to their Impala out in
the desert and then crashed into a cliff doing around 300MPH. The
story is a complete fabrication, and ends up being posted to the
Impala mailing list about once a month.
Two sensors are mounted in the block to detect knock or detonation
in the engine. If it is detected, the PCM retards the spark to
prevent damage to the engine. This allows for variations in octane
levels without damaging the engine. Often referred to by the
acronym KS. There is also a module inside the PCM that is used to
monitor for knock from the sensors.
Acronym for the Knock Sensor.
Acronym for the Mass Airflow Sensor. The MAF sensor used on the
Impala is the hot-wire type. The output frequency from the MAF is
a function of the power required to keep the air flow sensing
elements (hot wire) at a fixed temperature above ambient. As air
flow increases, a greater amount of current is required to keep
the wires at a constant temperature due to the cooling affect of
the increased quantities of air. The MAF is directional and must
be installed in the proper direction.
Malfunction Indicator Lamp
This is the infamous "Service Engine Soon" light. It indicates to
the driver that a problem has occured and that the vehicle should
be taken in for service as soon as possible. The light will go off
when the engine is restarted unless there is a failure in the
self-diagnostics of the MIL system. In any case, a trouble code
(DTC) is stored for later retrieval via a scan tool. A lit MIL
does not mean that the engine should be stopped immediately:
rather, the cause of the MIL should should be checked as soon as
Acronym for Manifold Absolute Pressure. This sensor measures the
change in the intake manifold pressure as speed and engine load
changes. As the manifold pressure increases, the air density in
the intake manifold also increases.
Acronym for Malfunction Indicator Lamp.
Special oil filler cap that was supplied on Corvettes equipped
with Mobil 1 from the factory. States to use "Mobil 1 Oil Only".
Will fit Impalas with the 'Vette valve covers or stock '94
Special notification plate that was supplied on Corvettes equipped
with Mobil 1 from the factory. States to use "Mobil 1 Oil Only". A
nice addition for those Impalas using Mobil 1 oil.
Acronym for National Association of Impala SS Owners, a nationwide
organization of over 500 Impala SS Owners.
runs it from Florida, and there are many regional chapters
springing up all over.
Abbreviation for Heated Oxygen Sensors.
Acronym for On-Board Diagnostics II, a system instituted by a
Federal standards committee that forces the engine control system
to be able to monitor for a failure in any sensor in the emmisions
control circuitry. This is only fully implemented on 1996 Impalas.
This required PCM changes and an extra set of oxygen sensors to be
fitted to 1996 Impalas.
A run mode of the engine when it is first started. In this mode,
the PCM ignores the oxygen sensors and calculates the air/fuel
ratio based upon inputs from the MAF, ECT, and TP sensors. The
system stays in this mode until the O2 sensors have varying
values, the coolant temperature has raised to a preset value, and
a preset amount of time has expired.
The distributor ignition system on the LT1 engine. This system
utilizes an optical sensor to detect timinng pulses on the
crankshaft. The PCM then receives both a low resolution (4x) and
high resolution (360x) signal to control timing to the injectors.
The LT1 in the Impala engine contains two heated oxygen sensors
near the catalytic converters. These oxygen sensor provide
feedback to the PCM that tells it if the engine is running rich or
lean. A voltage of 450mV from the oxygen sensor indicates that the
engine is running perfectly (stoichometric), which means that all
of the air and all of the fuel are being used during the
combustion process. If the value is lower than 450mV, the engine
is running lean, which means that there was too much oxygen in the
combustion process. If it is greater than 450mV, the engine is
running rich. The PCM adjusts in both the short and long term for
the effects of the oxygen sensors. The O2 sensors do not work
until they have reached about 600 degress F. Until then, they look
like an open circuit to the engine, and the PCM must "guess" what
mixture to use. Also, the O2 sensors are ignored by the PCM during
wide-open throttle time periods.
Acronym for Personalized Automotive Security System. General
Motors designed anti-theft system. It operates by using a specific
resistor in the ignition key. A signal is sent to the PCM only if
the corect resistor is detected that will enable the starter
circuit and the injectors. The car will not run even if the crank
circuit is bypassed (hot-wired). A DTC is stored if the wrong
resistor is sensed by the PCM.
Acronym for Powertrain Control Module
Acronym for Pressure Control Solenoid. This solenoid allows the
PCM to vary the line pressure to the transmission to make shifts
crisper and harder based upon throttle position, engine RPM, etc.
This feature allows for aftermarket PCM programs to incorporate an
electronic "shift kit" without opening up the transmission.
Acronym for Purple Door Panels. Some Impala door panels come from
the factory with a purple tint to them. They tend to very: some
may have a definite purple color, others may be slightly tinted.
We are in the process of trying to get GM to issue an official TSB
on this issue, otherwise, you can take your chances on getting
your local dealer to replace them for you.
A slang term invented for the rectangular resonator that connects
the air cleaner box to the MAF sensor. Its purpose is to reduce
the noise level of the intake air path. It is so named because of
its relationship with Home Plate and its rectangular shape.
A condition entered into by the PCM during wide open throttle
(WOT). During this time, the PCM gives the engine extra fuel for
more power. Short term fuel trim is not used during this mode, nor
are the oxygen sensors, since the mixture is inherently rich.
Powertrain Control Module
The heart of the control system on the LT1 engine. It monitors
sensors to retrieve information about engine operation and the
various systems that it controls. It also has the ability to do
diagnosis on itself and other parts of the system, and light the
MIL and store a DTC if it senses a problem.
Acronym for Power Steering Pressure switch. When the power
steering pressure is high, the PCM is alerted so that it can raise
idle speed to prevent the engine from stalling under the increased
Acronym for Random Access Memory. This is the PCM's scratch pad.
The processor can read or write from this memory as needed. This
memory is erasable and requires battery power to be retained. If
the battery is disconnected, this memory is lost. The DTC's are
stored in RAM.
Acronym for Red Bow Tie. The red bow-tie has become the unofficial
symbol of NAISSO. It involves replacing or taping over the OEM
chrome bow-tie on the grill of the Impala. There is a nice unit
from the Cavailier that does it nicely. This is the only part of
Jon Moss's concept car that didn't make it into production.
Acronym for Remote Control Door Lock Receiver, the unit mounted in
the trunk that receives the remote locking keychain signals and
sends the signals to lock or unlock the doors
A baffle meant to reduce noise in an air passageway. There are
several baffles on the Impala. The first is a black rectangular
piece after the air clean but before the MAF. The second is the
triangular black plastic piece that sits on top of the engine.
These two resonators serve to reduce air noise entering the
engine. There are also two exhaust resonators just before the tips
at the rear of the car. These serve to reduce exhaust noise.
Acronym for Read-Only Memory. There is permanent memory physically
soldered into the boards within the PCM. The ROM contains the
overall control programs. Once the ROM is programmed at the
factory, it cannot be changed. It is non-erasable, and does not
require battery power to be retained.
A hand-held electronic tool used to analuze and diagnose control
module systems. It can be used to read DTC's stored in the PCM,
monitor sensor data in real time, or flash the PCM with a new
program. The primary tool used GM technicians is the Tech 1. Other
aftermarket tools are also available, such as JET's Auto X-Ray and
the Diacom monitor. These tools are useful for tuning and for
Acronym for Service Engine Soon, which is what is commonly
displayed on the Malfunction Indicator Lamp indicator. The lamp is
now more properly referred to as the Malfunction Indicator Lamp,
Slang for the common practice of using PVC tubing from the
plumbing section of your local home goods store to replace the
first base resonator. Two elbows make an almost exact fit between
the stock instake elbow and the air box
Acronym for Sequential Multiport Fuel Injection
Slang for the mesh piece of metal inside of the export exhaust
pipes. It resembles a shower drain cover, and is probably in place
to quiet the exhaust as it passes through the straight pipes. Most
Acronym for Supplemental Inflatable Restraint, which is the
technical term for GM's version of the air bag.
Acronym for Sewer Pipe Equipped, which refers the the homemade PVC
pipe intakes installed on some cars.
A mode of operation where the engine determines the fuel needs
from engine speed and air density. The air density is computed
from the IAT and MAP sensors. These inputs allow the PCM to
compute the amount of fuel it needs to deliver via the injectors.
This method is less accurate than reading the MAF sensor and is
only used if there is a fault in the MAF circuit. On OBD-II cars,
this method is used to check the MAF for errors. This method
requires changes to the PCM to compensate for modifications to the
Super Sport, a moniker commonly given to some of Chevrolets high
A chemical term used when both elements in a process are
completely used in a reaction. In this case, it refers to the
oxygen and the fuel being burnt in the engine. This air/fuel ratio
is usually 14.7:1.
Acronym for Steering Wheel Controls, which allows you to adjust
radio parameters from buttons placed on the steering wheel.
The bulbs used in the export headlights that produce a generally
brighter and sharper beam than the standard.
Acronym for Torque Converter Clutch. The torque converter allosw
limited slippage inside of the transmission to allow the engine to
spool up into its power band quicker, and to allow the engine to
idle while still in gear. The TCC "locks up" via this clutch while
at highway speeds to reduce parasitic losses through the slippage.
Lockup is controlled via the PCM.
A hand-held scan tool most commonly used by GM technicians. They
cost upwards of $1000 each, but are very complete in their
coverage of the LT1 engine parameters and have the capability to
flash the PCM with a new program.
Acronym for Transmission Fluid Temperature. A sensor input used by
the PCM for unknown purposes, probably to control shift feel.
The throttle body is located on the front of the engine attached
to the intake manifold. Its job is to control air flow to the
engine based on the throttle position, which controls the speed of
the engine. During idle, the throttle body is almost closed and
idle speed is controlled by the IAC valve.
Provides a voltage to the PCM that changes in relationship to the
throttle blade opening or closing. This signal varies from about
.6 volts as idle to about 5 volts at WOT. The TPS is one of the
most important sensors used by the PCM for fuel control and most
of the other PCM controlled outputs.
Acronym for Throttle Position Sensor.
Acronym for Twilight Sentinel.
Acronym for Technical Service Bulletin. These are short papers
distributed to GM technician to help them diagnose and remedy
common complaints and problems. They are not the same as recalls,
which are done at no cost to the consumer and are usually only
performed for safety reasons. TSBs are usually covered under the
original warranty, if it is still in effect.
The twilight sentinel uses a sensor near the defogger vent to
detect whether it is light or dark outside. If it is dark, it
automatically turns the headlights on. Similarly, if it is light,
it turns them off. It also has a feature that leaves the lights on
for a specified period of time after the car is shut off as a
security measure. This option is incompatible with DRLs.
Acronym for Underhood Electrical Center. This is a black box that
is located near the firewall on the passengers side. Inside the
box you will find various fuses and relays, and beside it you will
find the auxiliary battery terminal.
A permanent magnet generator located in the transmission. It
transmits a pulsing AC voltage in relation to the speed of the
vehicle. The PCM converts the pulsing frequency to a speed and
sends it to the speedometer, odometer, cruise control, chime
module, and power steering control module.
Acronym for the Vehicle Speed Sensor
Acronym for Wide Open Throttle. This occurs when the throttle is
opened more than about 75%.
Option code for the Camaro high performance package. Many of the
parts from the current generation of the Camaro Z28 will fit