Acronyms And Definitions

2V  : Two Valves per engine cylinder

3V  : Three Valves per engine cylinder

4V  : Four Valves per engine cylinder

4WDIWE  : 4-Wheel Drive Integrated Wheel Ends

4WDL_IL  : 4-Wheel Drive Low Indicator Lamp

4WDMCS  : 4-Wheel Drive Mode Command Switch

4WD_POS1/2/3/4  : 4-Wheel Drive Motor Position (1-4)

4WDSWRTN  : 4-Wheel Drive Mode Command Switch Return

4WDT_IL  : 4-Wheel Drive Tow Indicator Lamp

4WDL  : 4-Wheel Drive Low Switch

ABS  : Anti-Lock Brake System

A/C  : Air Conditioning

A/CC  : Air Conditioning Clutch

A/CCR  : A/C Clutch Control Relay

ACCS  : Air Conditioning Cycling Switch

ACD  : Air Conditioning Demand. A signal input to the PCM from the air conditioning control panel.

ACDS  : Air Conditioning Diagnostic Switch (refrigerant containment switch)

ACET  : Air Conditioning Evaporator Temperature (may also be referred to as Evaporator Air Discharge Temperature)

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

ACPSW  : Air Conditioning Pressure Switch

ACPT  : Air Conditioning Pressure Transducer (Switch)

ACP V  : Air Conditioning Pressure Volts. A voltage input to the PCM from the ACP switch or sensor.

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

ADC  : See ATDC.

AFCM  : Alternative Fuel Control Module

AIR  : Secondary Air Injection

AIRB  : Secondary Air Injection Bypass

Air Diverter  : Air Diverter Valve. Part of the EAIR system. Diverts fresh air to the exhaust system when the electric air pump is commanded on.

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

Air/Fuel Ratio  : Air-to-fuel mixture ratio. An air-to-fuel mixture that is 14.7:1 is also called stoichiometry.

AIRM  Secondary AIR pump monitor

ALTCOM  : Alternator Command

ALTMON  : Alternator Monitor

Ambient Air Temperature  : Temperature of the air surrounding an object.

Analog (Electrical/Electronic)  : An electrical signal that may obtain any value within the voltage limits of the signal.

APP  : Accelerator Pedal Position

ARB  : Air Resource Board

ARPMDES  : Ancillary RPM Desired. RPM required to maintain the vehicle speed commanded by the Speed Control Command Switch (SCCS) input

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

Base Idle  : Idle RPM determined by the throttle lever hardset on the throttle body.

Base Timing  : Spark advance in degrees before top dead center of the base engine without any control from the PCM.

Battery Positive Voltage (B+)  : The positive (+) voltage from the battery or any circuit connected directly to the battery.

BATTEMP  : Battery Temperature

BJB  : Battery Junction Box

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

BPA  : Brake Pedal Applied. Typically located on the braking system master cylinder. Can be hydraulic or electric.

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.

Bus + or Bus -  : Multiplex circuits that carry standard corporate protocol (SCP) or controller area network (CAN) data from module to module and to the data link connector (DLC).

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

CAC  : Charge Air Cooler. Formerly known as intercooler. 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

CANP  : Canister Purge Solenoid

CANVNT  : Canister Vent

Catalyst  : Catalytic converter. An in-line exhaust system device used to reduce the level of engine exhaust emissions.

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.

Centralized Testing Facility  : State government operation. Provides inspection/maintenance (IM) and safety inspections.

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

CHT  : Cylinder Head Temperature. Units are displayed in either degrees Celsius or Fahrenheit.

CHTIL  : Cylinder Head Temperature Indicator Lamp

CHTV  : Cylinder Head Temperature Voltage

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

CMCVM  : Charge Motion Control Valve Monitor

CMP, CMP1, CMP2  : Camshaft Position

CMPFM  : Camshaft Position Failure Mode. Indicates when the PCM identifies a CMP fault.

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.

Coil  : A device consisting of windings around an iron core. In a spark ignition system, designed to increase voltage.

Cold Soak  : Time given to a vehicle to sit at a low temperature, typically below 20°C (68°F), until the temperature of external and internal components stabilize.

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

Continuous Memory Self-Test  : A continuous test of the EEC system conducted by the PCM whenever the vehicle is operating.

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

CPP  : Clutch Pedal Position

CPP Switch  : Clutch Pedal Position Switch. Located on the clutch pedal and detects when the clutch pedal is pressed.

CQIS  : Common Quality Indicator System

CSE GND  : Case Ground

CT:  Closed Throttle. A mode when 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.

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.

Digital  : Controls process information by switching the current or voltage ON and OFF

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

DLC  : Data Link Connector. 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 fault condition identified by the OBD system.

E-85  : Fuel containing 85% ethanol alcohol.

EAIR  : Electric Secondary Air Injection. A pump-driven system for providing secondary air using an electric air pump.

EAIRM  : Electric Air Pump Monitor

ECT  : Engine Coolant Temperature. Displayed in either Celsius or Fahrenheit.

ECTV  : Engine Coolant Temperature Voltage

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

EEC  : Electronic Engine Control

EEC-V  : Fifth-generation EEC system.

EFTA  : Engine Fuel Temperature A (bank 1)

EFTAV  : Engine Fuel Temperature A Voltage

EFTB  : Engine Fuel Temperature B (bank 2)

EFTBV  : Engine Fuel Temperature B Voltage

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

EGR EVAL  : Exhaust Gas Recirculation System Evaluated. EGR EVAL will display YES when the monitor is complete.

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

EGRMDSD  : Electric Exhaust Gas Recirculation Motor Desired position. The PID name used to operate the EEGR valve.

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.

EGRVRA  : Exhaust Gas Recirculation Vacuum Regulator Actual (volt). The actual state of the commanded output.

EGRVRF  : Exhaust Gas Recirculation Vacuum Regulator Fault. Represents whether a fault exists in the EGRV circuit.

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.

EI-LDR  : Electronic Ignition-Low Data Rate. Formerly known as 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.

EOT  : Engine Oil Temperature

EPA  : Environmental Protection Agency (United States Government)

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

ESM  : EGR System Module

ESOF  : Electronic Shift-on-the-Fly

ETB  : Electronic Throttle Body

ETC  : Electronic Throttle Control

ETCIL  : Electronic Throttle Control Indicator Lamp

ETCVREF  : 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.

EVAPCPF  Evaporative Canister Purge Solenoid Fault. Identifies whether an electrical fault exists for the current commanded state.

EVAPCV  : Evaporative Canister Vent Solenoid. A solenoid which seals the EVAP system from the atmosphere during the EVAP monitor test.

Evaporative Emissions Canister  : An evaporative emission canister containing activated charcoal which absorbs and holds fuel vapors.

EVAPPDC  : Evaporative Canister Purge Duty Cycle. The duty cycle commanded to the EVAP canister purge solenoid by the PCM.

EVO  : Electronic Variable Orifice

Electric VMV  : Electric Vapor Management Valve also known as the EVAP canister purge valve.

EWP  : Electric Water Pump

Exciter Ring  : A toothed or notched iron or steel disk.

FAN  : Fan Speed

FANSS:  Fan Speed Sensor

FC, FC1, FC2, FC3:  Fan Control

FCS  : Fuel Control Solenoid

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

FCV  : Fan Control-Variable

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

FICM  : Fuel Injector Control Module

FIM  : Fuel Indicator Module

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.

FLI V  : Fuel Level Input Voltage

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.

FPC  : Fuel Pump Control

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

FPF  : Fuel Pump Fault. Identifies whether a fault exists in the FP circuit.

FPM  : Fuel Pump Monitor. Monitors the fuel pump/circuits for faults.

Freeze Frame  : A block of memory containing the vehicle operating conditions at a specific time.

FRP  : Fuel Rail Pressure

FRP  V: Fuel Rail Pressure Voltage. A voltage input to the PCM from the fuel rail pressure sensor.

FRT  : Fuel Rail Temperature

FSC  : Fail-Safe Cooling

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

FTP  : Fuel Tank Pressure

FTP  V: Fuel Tank Pressure Voltage. From the FTP transducer.

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 HO2S1.

FUELPW2  : Fuel Injector Pulse Width #2. Corresponds to injectors normally affected by HO2S2

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

Fuel Tank Vapor Valve  : A valve mounted in the top of the fuel tank that vents excess vapor and pressure from the fuel tank into the evaporative emission control system.

FWD  : Front Wheel Drive

GEM  : Generic Electronic Module

GEN  : Generator

GENIL  : Generator Indicator Lamp. A PCM output signal used to control the charging system indicator.

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

GENRC  : Generator Regulator Control. A PCM output signal used to control the voltage regulator.

GENF  : Generator Output Fault

GENFDC  : Generator Field Control Output

GFS  : Generator Field Signal

GND  : Ground

GPM  : Grams per Mile. Also known as Gallons per Minute.

Green State Vehicle  : Formally known as California Emissions. A vehicle that is equipped with California on-board diagnostics.

GSS  : Gear Select Solenoid

GVW  : Gross Vehicle Weight

Hall effect  : A process where current is passed through a small portion of semiconductor material and a magnetic field to produce a small voltage in the semiconductor.

Hard Fault  : A fault currently present in the system.

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

HFC  : High Fan Control

HFCF  : High Fan Control Fault. Identifies if there is a fault in the HFC circuit.

HFP  : High Fuel Pump

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

HO  : High Output

HO2S  : Heated Oxygen Sensor. Provides information on rich or lean exhaust conditions to the PCM.

Hot Soak  : Period of time after an engine operates where localized combustion heat dissipates throughout the engine.

HTR11, HTR12, HTR13, HTR21, HTR22  : HO2S Heater. Heater element for the HO2S sensor.

Hydrogen  : Chemical symbol H. Highly flammable gas.

Hz  : Hertz. Cycles per second.

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

IAT  : Intake Air Temperature

IATV  : Intake Air Temperature Voltage. Actual voltage drop across the IAT sensor.

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

IAT2V  : Intake Air Temperature 2 Voltage. Actual voltage drop across the IAT2 sensor.

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.

IFDM  : Integrated Fuel Delivery Module

IFS  : Inertia Fuel Shut Off

IGN GND  : Ignition Ground

Ignition  : System used to provide high voltage spark for internal combustion engines.

IGN_KEY (IGKY)  : Ignition Key

IGN_SW (IGSW)  : Ignition Switch Position

ILC  : Generator I-Line Control. A generator feedback signal provided to the PCM.

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 faults.

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.

Injector  : A device for delivering metered pressurized fuel to the intake system or the cylinders.

Intake Air  : Air drawn through a filter and distributed to each cylinder for use in combustion.

Intercooler  : See CAC.

IPATS  : Integrated Passive Anti-Theft System

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.

KEYPWR  : Key Power. Battery voltage supplied when the ignition switch is in the ON position.

Knock  : A sharp metallic sound produced when 2 combustion pressure fronts collide in the combustion chamber of an engine.

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  : Kilopascals. Unit of pressure. 3.386 kPa = 1 inch of mercury (Hg).

KS  : Knock Sensor. Detects engine knock.

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

LONGFT1, LONGFT2  : Long-Term Fuel Trim. Fuel flow adjustment determined by the PCM.

LOOP  : Indicates OPEN or CLOSED loop status.

LPG  : Liquefied Petroleum Gas

LPLR  : Low Pressure Low Resistance fuel injector.

M-85  : Fuel containing 85% methanol alcohol.

MAF  : Mass Air Flow

MAF RTN:  Mass Air Flow Return. A return circuit for the MAF sensor.

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

Microprocessor  : A device that controls logic and arithmetic functions.

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

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.

On-Demand Test  : The KOEO and KOER tests of the PCM initialized by a technician.

OC  : Oxidation Catalytic converter. A catalytic converter system that reduces the levels of HC and CO emissions.

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

OWL  : Overheat Warning Lamp or its signal output from the PCM. Turns the TEMP warning lamp ON when the engine oil temperature exceeds safe limits.

Open Circuit  : A circuit which does not provide a complete path for the flow of current.

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

OSC  : Output State Control

OSS  : Output Shaft Speed

OTM  : Output Test Mode

Ozone  : A blue, gaseous form of oxygen (O 3 ) formed naturally by electric discharge or exposure to ultraviolet radiation.

Particulate  : Small solid matter found in exhaust gases, especially prevalent in diesel engines.

PATS  : Passive Anti-Theft System

PATSIL  : Passive Anti-Theft System Indicator Lamp

PATSIN  : Passive Anti-Theft System Receive Signal

PATSOUT  : Passive Anti-Theft System Transmit Signal

PATSTRT  : Passive Anti-Theft System Starter Relay Control

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

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

PF  : Purge Flow. Amount of fuel vapor burned in the engine.

Photochemical  : Term describing the action of light on air pollutants which results in creating smog.

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

Powertrain  : Engine and transmission/transaxle components.

Pressure - Absolute  : A pressure referenced to a perfect vacuum.

Pressure - Atmospheric  : The pressure of the surrounding air at any given temperature and altitude. Sometimes called Barometric Pressure.

Pressure - Barometric  : Pertaining to atmospheric pressure or the results obtained by a barometer.

Pressure - Differential  : The pressure difference between 2 regions, such as between the intake manifold and the atmospheric pressure.

Pressure - Gauge:  The amount by which the absolute pressure exceeds the atmospheric pressure.

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

Potentiometer  : An adjustable resistance component commonly used as a sensor (example: TP sensor).

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

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

Protocol  : A set of rules for the exchange of information on a network.

PSOM  : Programmable Speedometer/Odometer Module. A module that processes vehicle speed information.

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

PSP  V: Power Steering Pressure Input Voltage

PSPT  : Power Steering Pressure Transducer

PTEC  : Powertrain Electronic Controller

PTO  : Power Take-Off

PTOIL  : Power Take-Off Indicator Lamp

PTO LOAD  : Power Take-Off Load

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.

Quick Test  : A series of diagnostic tests of the EEC system consisting of KOEO, KOER, and Continuous Memory Self-Tests. The results are displayed as a series of DTCs.

RABS  : Rear Anti-lock Brake System

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

RDI  : Restraint Deployment Indicator

REDOX  : Reduction Oxidation Catalytic converter. A catalytic converter system designed to operate at high temperatures.

Regulator  : Controls the alternator/generator field current to maintain the proper battery charge. Contained within the PCM in smart charging applications.

Relay  : An electromechanical device in which connections in one circuit are opened or closed by changes in another circuit.

REM  : Rear Electronic Module

Repetitive Spark  : Multiple firings of individual spark plugs at engine speeds of less than 1000 RPM to improve idle quality and improve emissions.

RF  : Radio Frequency

RFI  : Radio Frequency Interference

RFS  : Return FUEL SYSTEM

RLC  : Reverse Lamp Control

RM  : Relay Module. A module containing 2 or more relays.

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

RON  : Research Octane Number

Routine  : A group of related tasks, such as a series of diagnostic tests.

RPM  : Revolutions Per Minute

RS  : Reverse Switch

RTN  : Return. A dedicated sensor ground circuit.

RWD  : Rear Wheel Drive

SAE  : Society of Automotive Engineers

SAIR  : Secondary Air

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

SC  : Supercharged or Supercharger

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

SCBCF  : Supercharger Bypass Control Fault. Identifies whether a fault exists in the Supercharger Bypass circuit.

SCCS  : Speed Control Command Switch

SCICP  : Supercharger Intercooler Pump Control

SCICPF  : Supercharger Intercooler Pump Control Fault

SCIPC  : The PID to monitor the operation of the Supercharger and Charge Air Cooler pump.

SCP  : Standard Corporate Protocol

Self-Test  : See Quick Test.

Sensor  : A device that detects the value or change in a physical quantity, such as temperature, pressure, or flow rate, and converts the data into an electrical signal.

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

Shield  : A conducting sleeve that surrounds wires to be electronically isolated from electromagnetic interference (EMI).

Short Circuit  : An undesirable condition in a circuit where the circuit termination is at a point other than that intended.

SHRT FT  : 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 sensor

SIL  : Shift Indicator Lamp

Smart Driver:  A PCM output driver that can detect faults (open or shorts) on its output circuit.

SME  : Society of Manufacturing Engineers

SMR  : Starter Motor Request. An input signal provide to the PCM when the ignition switch is in the START position.

SOF  : Shift-on-the-Fly

SOHC:  Single Overhead Cam

Solenoid  : A device consisting of an electrical coil which produces a magnetic field which changes the position of a metal plunger.

Stoichiometry  : An air/fuel mixture that is neither too rich nor too lean. Stoichiometric ratio is 14.7 parts of air for every 1 part of fuel.

Switch  : A device for making, breaking, or changing the connections in an electrical circuit.

TA  : Traction Assist

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

Tear Tag  : The label attached to the PCM to identify its calibration.

Thermistor  : A temperature dependent resistor, like that used in CHT and ECT sensors.

Timing  : The relationship between spark plug firing and piston position expressed in crankshaft degrees before (BTDC) or after (ATDC) top dead center of the compression stroke.

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

TP1  : Throttle Position 1

TP2  : Throttle Position 2

TP V  : Throttle Position sensor Voltage

Transducer:  A device that receives energy from one medium and transfers it to another. For example, thermal energy is converted to an electrical signal through a temperature probe.

Transmissions/Transaxles: 

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

Underspeed Mode:  A control mode that prevents the engine from stalling in the event it stumbles while running. Also used during engine crank.

Vacuum  : Manifold pressure that is reduced below the ambient atmospheric pressure.

Variable Reluctance  : A process of passing a varying magnetic field through wire windings and inducing a voltage.

VCT, VCT1, VCT2  : Variable Camshaft Timing

VDF  : Visctronic Drive Fan

VECI  : Vehicle Emission Control Information label

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.

Wastegate Control  : A device that opens the wastegate in case of overboost from a turbocharger.

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

Zip Tube  : Another name for fresh air duct or air inlet duct.

Transmissions: 

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

4x4L  : 4x4 Low

A/T  : Automatic Transmission

CCS  : Coast Clutch Solenoid

CCSF  : Coast Clutch Solenoid Fault. Displays a YES if a fault exists.

EPC, EPC1, EPC2  : Electronic Pressure Control

EPCV  : Electronic Pressure Control Volts

ESS  : Electronic Shift Scheduling

HCDSS  : High Clutch Drum Speed Sensor. PCM input from the 4R44E and 4R55E.

ISS  : Intermediate/Input Shaft Speed Sensor

M5OD  : Manual 5-Speed transmission with overdrive (RWD).

M/T  : Manual Transmission/Transaxle

NPS  : Neutral Pressure Switch or its signal input to the PCM.

OCS  : Overdrive Cancel Switch

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

PNP  : Park/Neutral Position switch. Also known as Neutral Drive Switch (NDS), Neutral Gear Switch (NGS), and Transmission Switch Neutral (TSN).

REVERSE or REV  : Transmission Reverse Switch Input

SIL  : Shift Indicator Lamp. A lamp that indicates the preferred shift points on select manual transmission/transaxle vehicles.

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.

Torque converter  : A device which by its design multiplies the torque in a fluid coupling between an engine and transmission/transaxle.

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

Transaxle  : A device consisting of a transmission and axle drive gears assembled in the same case. Front-wheel drive and some all-wheel applications.

Transmission  : A device which selectively increases or decreases the ratio of relative rotation between its input and output shafts. Rear-wheel drive applications.

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

TR Sensor  : Provides information to the PCM on the transmission range selector position.

TR V  : Transmission Range Voltage

TRO-N  : Transmission Range Output Neutral

TRO-P  : Transmission Range Output Park

TS1  : Transmission Range Sensor - 1st

TSD  : Transmission Range Sensor - Drive

TSR  : Transmission Range Sensor - Reverse

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.