Acronyms And Definitions

2V:  Two valves per engine cylinder

3V:  Three valves per engine cylinder

4V:  Four valves per engine cylinder

ABS:  Anti-Lock Brake System

A/C:  Air Conditioning

A/CC:  Air Conditioning Clutch

A/CCR:  Air Conditioning Clutch Control Relay

ACCS:  Air Conditioning Cycling Switch

ACDS:  Air Conditioning Diagnostic Switch (refrigerant containment switch)

ACET:  Air Conditioning Evaporator Temperature

ACP:  Air Conditioning Head Pressure or A/C cycling switch input state

ACPSW:  Air Conditioning Pressure Switch

ACPT:  Air Conditioning Pressure Transducer (Switch)

A/D:  Analog-to-Digital. Analog-to-Digital signal conversion.

AFCM:  Alternative Fuel Control Module

AIR:  Secondary Air Injection

AIRB:  Secondary Air Injection Bypass

AIR EVAL:  Air System Evaluated. Displays a YES or NO status indicating whether the AIR System has been evaluated for On-Board Diagnostic (OBD) purposes.

AIRM:  Secondary Air Pump Monitor

APP:  Accelerator Pedal Position

ARB:  Air Resource Board

ASCII:  American Standard Code Information Interchange

ATDC:  After Top Dead Center. The location of the piston after it has reached the top of its stroke. Measured in degrees of crankshaft rotation.

AWD:  All-Wheel Drive

BARO:  Barometric Pressure

BJB:  Battery Junction Box

BOB:  Breakout Box. A test device which connects in series to the PCM and PCM harness.

BPA:  Brake Pedal Applied

BPP:  Brake Pedal Position

BPS:  Brake Pedal Switch/Speed Control Deactivation

BTDC:  Before Top Dead Center. The location of the piston before it has reached the top of its stroke. Measured in degrees of crankshaft rotation.

CAC:  Charge Air Cooler. A device which lowers the temperature of pressurized intake air.

CAFE:  Corporate Average Fuel Economy. A set of federal requirements and regulations which govern fuel economy standards.

CAN:  Controller Area Network

CAT EVAL:  Catalyst System Evaluated. This item indicates YES when the Catalyst Efficiency Monitor has successfully completed.

CCM:  Comprehensive Component Monitor

CD A through J:  Coil Driver 1 through 10

CGND:  Case Ground. Provides a ground source for the PCM case.

CHT:  Cylinder Head Temperature

CHTIL:  Cylinder Head Temperature Indicator Lamp

CKP:  Crankshaft Position

CKP+, CKP-:  CKP+ is the CKP sensor signal circuit. CKP- is the signal return circuit.

CL:  Closed Loop. An operating condition or mode which enables operation based on sensor feedback.

CMCV:  Charge Motion Control Valve

CMP, CMP1, CMP2:  Camshaft Position. CMP1 and CMP2 on V engines where applicable.

CMS:  Catalyst Monitor Sensor. The downstream HO2S.

CMVSS:  Canadian Motor Vehicle Safety Standards

CO:  Carbon Monoxide. A colorless, odorless, and toxic gas that is a component of auto exhaust emissions.

CO  ₂  :  Carbon Dioxide. A colorless, odorless gas that is a normal by-product of the combustion of fuel.

CONT:  Continuous Memory. The portion of keep alive memory (KAM) used to store DTCs generated during the continuous memory self-test.

COP:  Coil On Plug. Ignition coil on plug assembly.

CPP:  Clutch Pedal Position

CT:  Closed Throttle. A mode in which the PCM varies the pulse width of the fuel injectors to obtain the air/fuel mixture appropriate for closed throttle operation.

CTO:  Clean Tach Output. Signal used to drive the instrument panel tachometer.

CV:  Canister Vent Solenoid. A solenoid which seals the evaporative emission (EVAP) system from the atmosphere during the EVAP monitor test.

DC: 1.  Direct Current. Electric current flowing in one direction. 2. Duty Cycle. The voltage measurement of ON time versus the full cycle period, expressed in percent.

DCL:  Data Communication Link. A communication path between various in-vehicle electronic modules.

DI:  Distributor Ignition. A system in which the ignition coil secondary circuit is sequenced by a distributor.

DIS:  Distributorless Ignition System. A system in which the ignition coil secondary circuit is sequenced without a distributor.

DLC:  Data Link Connector. SAE standard J1962 connector providing access to vehicle diagnostic information.

DMM:  Digital Multimeter

DOHC:  Dual Overhead Cam. An engine configuration that uses 2 camshafts positioned above the valves.

DOL:  Data Output Line. A circuit that sends certain information from the PCM to the instrument cluster.

DPFEGR:  Differential Pressure Feedback Exhaust Gas Recirculation. A system that uses a pressure transducer to control the operation of the exhaust gas recirculation (EGR) vacuum regulator valve.

DRI:  Deposit Resistant Injector. A fuel injector designed to prevent the build-up of carbon and other unwanted deposits.

DTM:  Diagnostic Test Mode. A level of capability in an OBD system.

DTC:  Diagnostic Trouble Code. An alpha/numeric identifier for a concern identified by the OBD system.

E-85:  Fuel containing 85% ethanol alcohol

ECT:  Engine Coolant Temperature

ECU:  Electronic Control Unit. A module that handles the control strategy and monitors system inputs or outputs.

EEC:  Electronic Engine Control

EEGR:  Electric Exhaust Gas Recirculation (EEGR) System

EEPROM:  Electrically Erasable Programmable Read-Only Memory. An electronic component in the PCM that allows the electronic storage of information.

EGR:  Exhaust Gas Recirculation. A process in which a small amount of exhaust gas is routed into the combustion chamber.

EGRMC (1-4):  Electric Exhaust Gas Recirculation Motor Control

EGRT:  Exhaust Gas Recirculation Valve Temperature. A temperature sensor that is threaded into the bottom of the intake plenum.

EGRVR:  Exhaust Gas Recirculation Vacuum Regulator. A solenoid which controls vacuum to the EGR valve by varying the duty cycle signal from the PCM.

EI:  Integrated Electronic Ignition. An electronic ignition system that has the ignition control module (ICM) integrated into the PCM.

EI-HDR:  Electronic Ignition-High Data Rate. Formerly known as Electronic Distributorless Ignition System.

EMI:  Electromagnetic Interference. Usually caused by ignition voltage spikes, solenoids, relay operation, or noisy generator contacts.

EOL:  End of Line. A system designed specifically for use at assembly plants to make sure all new vehicles conform to design specifications.

EONV:  Engine Off Natural Vacuum

EOT:  Engine Oil Temperature

EPA:  Environmental Protection Agency (United States Government)

E-Quizzer:  Enhanced Quizzer

ESM:  EGR System Module

ESOF:  Electronic Shift-on-the-Fly

ETB:  Electronic Throttle Body

ETC:  Electronic Throttle Control

ETCREF:  Voltage Reference (5V) for ETC (APP VREF, TP VREF).

EVAP:  Evaporative Emissions. A system to prevent fuel vapor from escaping into the atmosphere.

EVAPCP:  Evaporative Canister Purge Solenoid. A solenoid which controls the venting of fuel vapor from the evaporative emissions canister into the intake manifold for combustion.

EVO:  Electronic Variable Orifice

EVR:  Electronic Vacuum Regulator Solenoid

EWP:  Electric Water Pump

FCS:  Fuel Control Solenoid

FCIL:  Fuel Cap Indicator Lamp. Indicates that the fuel filler cap is not correctly installed.

FEAD:  Front End Accessory Drive

FEPS:  Flash EEPROM Programming Signal. An 18-volt DC signal input from the diagnostic tool used by the PCM to initiate programming.

FFV:  Flexible Fuel Vehicle

FLI:  Fuel Level Input. Provides information on the amount of liquid fuel in the fuel tank. Used by the EVAP monitor to calculate the fuel tank vapor volume. Displayed as a percentage.

FMEM:  Failure Mode Effects Management. Operating strategy that maintains limited vehicle function in the event of a PCM or EEC component failure.

FP: 1.  Fuel Pump. Indicates whether the pump has been commanded ON or OFF by the PCM. 2. Fuel Pump (Modulated). Fuel pump duty cycle percentage.

FPDM:  Fuel Pump Driver Module. A module that controls the electric fuel pump.

FRP:  Fuel Rail Pressure

FRPT:  Fuel Rail Pressure Temperature

FSS:  Fan Speed Sensor

FSSW:  Fuel Select Switch. An output signal between the PCM and the fuel injector interface module which determines the fuel delivery mode.

FTP:  Fuel Tank Pressure

FUEL PR:  Fuel Pressure. Measurement of the force of the fuel delivered by the fuel pump.

FUELPW:  Fuel Pulse Width. Displays the commanded pulse width at the time of the last data update.

FUELPW1:  Fuel Injector Pulse Width #1. Corresponds to injectors normally affected by HO2S11.

FUELPW2:  Fuel Injector Pulse Width #2. Corresponds to injectors normally affected by HO2S21.

FUELSYS:  Fuel System Status (OPEN/CLOSED Loop). Formerly known as LOOP.

FWD:  Front Wheel Drive

GEN:  Generator

GENLI:  Generator Load Input. An input signal used by the PCM to monitor charging system operation and determine the system voltage.

GND:  Ground

GPM: 1.  Grams per Mile. 2. Gallons per Minute.

GVW:  Gross Vehicle Weight

GVWR:  Gross Vehicle Weight Rating

HC: 1.  Hydrocarbon. A by-product of combustion and a component of auto exhaust emissions. 2. High Compression.

HFC:  High Fan Control

HLOS:  Hardware Limited Operating Strategy. A mode of operation where the PCM replaces output commands with fixed values in response to internal PCM concerns.

HO:  High Output

HO2S:  Heated Oxygen Sensor. Provides information on rich or lean exhaust conditions to the PCM. HTR11, HTR12, HTR13, HTR21, HTR22:  HO2S Heater. Heater element for the HO2S sensor.

Hz:  Hertz. Cycles per second.

IAC:  Idle Air Control. Electrical control of throttle bypass air.

IAT:  Intake Air Temperature

IAT2:  Intake Air Temperature 2. Used on supercharged vehicles.

IC:  Integrated Circuit. A small semi-conductor device capable of many separate circuit functions.

ICM:  Ignition Control Module. The module that controls the ignition system.

IFS:  Inertia Fuel Switch

IMRC:  Intake Manifold Runner Control. Controls or modifies airflow in the intake air system.

IMRCM:  Intake Manifold Runner Control Monitor. Monitors the IMRC circuits for concerns.

IMTV, IMTV1, IMTV2:  Intake Manifold Tuning Valve. Controls airflow through runners in a split intake manifold.

INJ1, INJ2, INJ3, INJ4, INJ5, INJ6, INJ7, INJ8, INJ9, INJ10:  Injector number or its signal output from the PCM.

IPC:  Independent Plausibility Checker

ISO:  International Standards Organization

KAM:  Keep Alive Memory. A portion of the memory within the PCM that must have power even when the vehicle is not operating.

KAPWR:  Keep Alive Power. A dedicated and unswitched power circuit that maintains KAM.

KOEO Self-Test:  Key On Engine Off self-test. A test of the EEC system conducted by the PCM with power applied and the engine at rest.

KOER Self-Test:  Key On Engine Running self-test. A test of the EEC system conducted by the PCM with the engine running and the vehicle at rest.

Km/h:  Kilometers per Hour

kPa:  Kilopascal. Unit of pressure. 3.386 kPa equals 1 inch of mercury (Hg).

L:  Liters. The unit of volume in the metric measuring system. One liter equals 1.06 quarts.

LEV:  Low Emissions Vehicle

LFC:  Low Fan Control

LONGFT:  Long-Term Fuel Trim. Fuel flow adjustment determined by the PCM.

LPLR:  Low Pressure Low Resistance fuel injector

M-85:  Fuel containing 85% methanol alcohol

MAF:  Mass Air Flow

MAP:  Manifold Absolute Pressure. The internal pressure of the intake manifold.

MFC:  Medium Fan Control

MFI:  Multiport Fuel Injection. A fuel-delivery system in which each cylinder is individually fueled.

MFP:  Modulated Fuel Pump

MIL:  Malfunction Indicator Lamp. An indicator lamp alerting the driver of an emission related concern.

MISF:  Misfire. Any event in the cylinder that causes a sudden change in acceleration of the crankshaft.

MON:  Motor Octane Number

MSOF:  Manual Shift-on-the-Fly

MY:  Model Year

NA:  Naturally Aspirated. An engine that is not supercharged or turbocharged.

NC:  Normally Closed

NGS:  New Generation Self-Test Automatic Readout (STAR) tester

NO:  Normally Open

NO  _X  : Oxides of Nitrogen. Gasses formed at high combustion temperatures.

O2S11, O2S12, O2S13, O2S21, O2S22, O2S23:  Oxygen Sensor. Provides information on rich or lean exhaust conditions to the PCM.

OASIS:  On-line Automotive Service Information System

OBD, OBD-II:  On-Board Diagnostics, On-Board Diagnostics Second Generation. A system that monitors the PCM input and output control signals.

OCT ADJ:  Octane Adjust. Compensating strategy that adjusts for changes in fuel octane.

OEM:  Original Equipment Manufacturer

OHC:  Overhead Cam. An engine configuration that uses a single camshaft positioned above the valves.

OL:  Open Loop. An operating condition based on instructions not modified by PCM feedback.

ORVR:  On-Board Refueling Vapor Recovery

OSC:  Output State Control

OSS:  Output Shaft Speed

OTM:  Output Test Mode

PATS:  Passive Anti-Theft System

PCM:  Powertrain Control Module. Formerly known as the electronic engine control (EEC) processor.

PCMRC:  Powertrain Control Module Relay Control

PCV:  Positive Crankcase Ventilation. A system which allows the controlled flow of crankcase vapors into the combustion chamber.

PID:  Parameter Identifier. Identifies an address in the PCM memory which contains operating information.

PIP:  Profile Ignition Pickup. Provides crankshaft position information for ignition synchronization.

PPM:  Parts per Million. A measure used in emission analysis.

PROM:  Programmable Read-Only Memory. Similar to ROM, except without program instructions.

PSP:  Power Steering Pressure. Indicates the pressure in the power steering system.

PSPT:  Power Steering Pressure Transducer

PTO:  Power Take-Off

PW:  Pulse Width. The length of time an actuator, such as a fuel injector, remains energized.

PWM:  Pulse Width Modulation. Controls the intensity of an output by varying the signal duty cycle.

PWR GND:  Power Ground. The main ground circuit in the EEC system.

RABS:  Rear Anti-Lock Brake System

RAM:  Random Access Memory. Memory into which information can be written as well as read.

REM:  Rear Electronic Module

RF:  Radio Frequency

RFI:  Radio Frequency Interference

RFS:  Returnless Fuel System

ROM:  Read-Only Memory. Computer memory that can be accessed and used, but not altered.

RPM:  Revolutions Per Minute

RTN:  Return. A dedicated sensor ground circuit.

RWD:  Rear Wheel Drive

SAE:  Society of Automotive Engineers

SBS:  Supercharger Bypass Solenoid or its signal output from the PCM

SC:  Supercharged or Supercharger

SCB:  Supercharger Bypass

SCBC:  Supercharger Bypass Control. A system that allows manifold vacuum to be bled away from the supercharger wastegate actuator to allow for maximum boost.

SCP:  Standard Corporate Protocol

SFI:  Sequential Multiport Fuel Injection. A multiport fuel delivery system in which each injector is individually energized and timed relative to its cylinder intake event.

SHRTFT:  Short-Term Fuel Trim. Fuel flow adjustment in response to the HO2S sensor(s) input during closed-loop operation.

SIG RTN:  Signal Return. A dedicated sensor ground circuit that is common to 2 or more sensors.

SME:  Society of Manufacturing Engineers

SOHC:  Single Overhead Cam

TA:  Traction Assist

TAC:  Throttle Actuator Control

TACH:  Tachometer

TACM, TACMP, TACMN, TACP (+/-):  Throttle Actuator Control Motor +/- used in the ETC system.

TB:  Throttle Body. A device that controls airflow through the engine via a butterfly valve and has an air bypass channel around the throttle plate.

TC: 1.  Traction Control. Combines anti-lock braking and axle torque reduction to control wheel slippage. 2. Turbocharger.

TDC:  Top Dead Center

TP:  Throttle Position sensor. A potentiometer that provides throttle angle and rate information for the PCM.

TP1:  Throttle Position 1

TP2:  Throttle Position 2

TSB:  Technical Service Bulletin. Notifies technician of any known vehicle concerns, procedures, or general repair information.

VCT, VCT1, VCT2:  Variable Camshaft Timing. VCT1 and VCT2 on V engines where applicable.

VECI:  Vehicle Emission Control Information

VIN:  Vehicle Identification Number. A unique identification number given to every vehicle produced. Includes information about the year, model, engine, and plant origin of the vehicle.

VMV:  Vapor Management Valve. Also known as EVAPCP. Refer to EVAPCP.

VBPWR:  Vehicle Buffered Power. A PCM-supplied power source that supplies regulated voltage.

VPWR:  Vehicle Power. A switched circuit that provides power to the EEC system. Compare to battery voltage (B+).

VREF:  Reference Voltage. A dedicated circuit that provides an approximately 5.0 volt signal used as a reference by certain sensors.

WAC:  Wide Open Throttle A/C Cut-Off. Turns the A/C system off during wide open throttle or certain other operating conditions.

WOT:  Wide Open Throttle. A condition of maximum airflow through the throttle body.

Transmissions: 

• The first character, a number, is the number of forward gears.
• The second character, either the letter F or R, represents front (transaxle) or rear (transmission) wheel drive.
• The next set of characters, a grouping of numbers, represents the design torque capacity of the transmission/transaxle.
• The last character, if used, is one of the following:
  • E for electronic shift
  • N for non-synchronous shift
  • S for synchronous shift
  • W for wide ratio

As an example, for the 4F27E transaxle, the number of forward gears is 4, the character F indicates front transaxle, 27 represents 270 ft-lbs of torque capacity and the character E represents an electronic shift.

A/T:  Automatic Transmission

CCS:  Coast Clutch Solenoid

EPC, EPC1, EPC2:  Electronic Pressure Control

ESS:  Electronic Shift Scheduling

ISS:  Intermediate/Input Shaft Speed Sensor

M/T:  Manual Transmission/Transaxle

OCS:  Overdrive Cancel Switch

OSS:  Output Shaft Speed. Indicates the rotational speed of the transmission output shaft.

PNP:  Park/Neutral Position switch.

REVERSE or REV:  Transmission Reverse Switch Input

SSA/SSB/SSC/SSD/SSE:  Shift solenoids. Devices in an automatic transmission that control the shifting by varying fluid flow when commanded by the PCM.

SS1/SS2/SS3:  Shift solenoids. Devices in an automatic transmission that control the shifting by varying fluid flow when commanded by the PCM.

TCC/TCCH:  Torque Converter Clutch. When energized, causes a mechanical engagement and disengagement of the torque converter clutch.

TCIL:  Transmission Control Indicator Lamp. Indicates that the TCS has been activated.

TCS:  Transmission Control Switch. Modifies the operation of electronically controlled transmissions.

TFT:  Transmission Fluid Temperature. Indicates the temperature of transmission fluid.

TR, TR1, TR2, TR3, TR4:  Transmission Range. The range in which the transmission is operating.

TSS:  Turbine Shaft Speed. Indicates the rotational speed of the transmission turbine shaft.

VSS:  Vehicle Speed Sensor. A magnetic pickup device that generates an AC signal that is proportional to the vehicle speed.

VSOUT:  Vehicle Speed Output. A pulse width modulated vehicle speed signal.