Decoding Car Diagnostic Jargon: A Guide for Innova Owners & OBD2 Troubleshooting

Navigating the world of car repair can often feel like learning a new language. Acronyms and technical terms fly around, especially when dealing with modern vehicle diagnostics. For Toyota Innova owners, understanding these terms becomes crucial when faced with issues, particularly those related to the On-Board Diagnostics II (OBD2) system. One common frustration arises when an OBD2 scanner displays a “No Support” message, leaving drivers puzzled.

This guide, brought to you by carparteu.com, aims to demystify the jargon and empower you with the knowledge to better understand your vehicle’s diagnostics. We’ll explore common automotive terms, particularly those relevant to OBD2 systems and troubleshooting scenarios, including what to do when your scanner indicates “OBD2 No Sup” on your Innova or similar vehicle.

Understanding Essential Diagnostic Terms

Modern vehicles like the Toyota Innova are equipped with sophisticated computer systems that monitor various aspects of the engine and emissions. The OBD2 system is a standardized system that allows mechanics and car owners to access this information using diagnostic scanners. To effectively use these tools and understand repair information, familiarity with key terms is essential. Let’s delve into some fundamental concepts and acronyms:

Core Electrical and Electronic Terms

AC (Alternating Current): The type of electrical current that periodically reverses direction. Not typically used in standard car DC systems but relevant in some components and testing equipment.
DC (Direct Current): The standard type of electrical current in vehicles, flowing in one direction from the battery.
Ampere (A): The unit of measurement for electrical current flow.
Voltage (V): The electromotive force that causes electrons to flow, essentially the electrical pressure.
Resistance (Ohm): The opposition to the flow of electrical current in a circuit.
Circuit: A complete path for electrical current to flow.
Open Circuit: An incomplete circuit, preventing current flow.
Short Circuit: An unintended path of low resistance causing excessive current flow.
Ground: The common reference point in a circuit, typically connected to the vehicle chassis and battery negative terminal.
Sensor: A device that detects a physical quantity (like temperature, pressure, speed) and converts it into an electrical signal for the car’s computer.
Actuator: A device that performs an action based on commands from the car’s computer (e.g., a motor, solenoid, relay).
Module: A self-contained electronic control unit (ECU) or computer that manages specific vehicle functions.
PCM (Powertrain Control Module): The main computer in modern vehicles, controlling engine and transmission functions. Sometimes also referred to as ECM (Engine Control Module) or ECU (Electronic Control Unit).

Engine and Emission Control Terms

AFR (Air Fuel Ratio): The ratio of air to fuel in the engine’s combustion mixture. Crucial for engine efficiency and emissions.
EGR (Exhaust Gas Recirculation): A system that recirculates a portion of exhaust gas back into the intake to reduce NOx emissions.
Catalytic Converter (CC): An emissions control device that reduces harmful pollutants in the exhaust gas.
O2 Sensor (Oxygen Sensor): Measures the oxygen content in the exhaust gas to help the PCM adjust the air-fuel mixture for optimal combustion and emissions. Also known as HO2S (Heated Oxygen Sensor) for sensors with built-in heaters for faster warm-up.
MAF (Mass Air Flow Sensor): Measures the amount of air entering the engine.
MAP (Manifold Absolute Pressure) Sensor: Measures the pressure in the intake manifold, providing information about engine load and air density.
ECT (Engine Coolant Temperature) Sensor: Measures the engine coolant temperature, crucial for engine management and temperature regulation.
IAT (Intake Air Temperature) Sensor: Measures the temperature of the air entering the engine.
TPS (Throttle Position Sensor): Monitors the position of the throttle plate, indicating driver demand and engine load.
CKP (Crankshaft Position) Sensor: Monitors the position and speed of the crankshaft, essential for ignition and fuel injection timing.
CMP (Camshaft Position) Sensor: Monitors the position of the camshaft, used for precise valve timing and sequential fuel injection.
EVAP (Evaporative Emissions System): A system to prevent fuel vapors from escaping into the atmosphere.
MIL (Malfunction Indicator Lamp): The “Check Engine Light” that illuminates when the OBD2 system detects a fault. Also sometimes referred to as SES (Service Engine Soon) light.
DTC (Diagnostic Trouble Code): A code stored by the PCM when a fault is detected. These codes help diagnose problems.
OBD (On-Board Diagnostics): The vehicle’s self-diagnostic system.
OBD2 (On-Board Diagnostics II): The second generation of OBD, a standardized system mandated for most vehicles, offering more comprehensive diagnostics.
DLC (Data Link Connector): The diagnostic port where you connect an OBD2 scanner to access vehicle data and fault codes.

Example of an OBD2 port location under the dashboard.

Transmission and Drivetrain Terms

A/T (Automatic Transmission): A type of transmission that automatically changes gears.
TCC (Torque Converter Clutch): A clutch in automatic transmissions that can lock up to improve fuel efficiency.
ABS (Antilock Brake System): A safety system that prevents wheel lock-up during braking.
TCM (Transmission Control Module): The computer that controls the automatic transmission.
AWD (All-Wheel Drive): A drivetrain system that powers all four wheels.
FWD (Front Wheel Drive): A drivetrain system that powers the front wheels.
RWD (Rear Wheel Drive): A drivetrain system that powers the rear wheels.

Diagnostic Procedures and Scanner Terms

Scan Tool/Scanner: A device used to communicate with the vehicle’s OBD2 system, read DTCs, view live data, and perform tests.
Generic Code: A DTC that is standardized across all OBD2 compliant vehicles.
Manufacturer Specific Code: A DTC that is specific to a particular vehicle manufacturer.
Pending Code: A DTC that has been detected but needs confirmation on a subsequent drive cycle to become a confirmed “active” code.
Freeze Frame: A snapshot of sensor data recorded by the PCM at the moment a DTC is set.
Live Data/Parameter Identification (PID): Real-time data from sensors and systems that can be viewed on a scan tool.
Actuator Test Mode (ATM): A diagnostic mode to activate specific output circuits (actuators) to check their operation.
Drive Cycle: A specific sequence of driving conditions required to run certain OBD2 system monitors and confirm repairs.
KOEO (Key On, Engine Off): A diagnostic test condition with the ignition key turned to the “ON” position but the engine not running.
KOER (Key On, Engine Running): A diagnostic test condition with the engine running.

Troubleshooting “OBD2 No Sup” on Your Innova

Encountering a “OBD2 No Sup” or “Scanner Not Supported” message when trying to connect your OBD2 scanner to your Toyota Innova can be frustrating. This typically indicates a communication problem between the scanner and your vehicle’s computer system. Here are common reasons and troubleshooting steps:

Scanner Compatibility:
- Generic vs. Vehicle-Specific Scanners: While OBD2 is a standard, some very basic generic scanners might have compatibility issues with certain vehicle makes or models, especially with advanced systems in vehicles like the Innova. Try using a higher-quality, more reputable OBD2 scanner or one known to be compatible with Toyota vehicles.
- Protocol Mismatch: OBD2 uses various communication protocols (like CAN, ISO, PWM, VPW). It’s possible your scanner doesn’t fully support the specific protocol used by your Innova. Check your scanner’s specifications and ensure it covers the necessary OBD2 protocols.
Vehicle-Side Issues:
- DLC Port Problems: The DLC port itself might be damaged, have bent pins, or corrosion, preventing proper connection. Visually inspect the DLC port under your dashboard.
- Wiring Faults: The wiring connecting the DLC port to the vehicle’s computer system could be damaged, broken, or have a short circuit. This is less common but possible.
- PCM/ECU Issues: In rare cases, the vehicle’s PCM or ECU itself might have a communication fault, preventing it from responding to the scanner. This is usually accompanied by other significant vehicle problems.
- Fuse Problems: A blown fuse that powers the DLC port or the PCM can prevent scanner communication. Check your vehicle’s fuse box diagram and inspect relevant fuses (often labeled “OBD,” “ECU,” “Diagnostic,” or similar).
Scanner Operation:
- Scanner Malfunction: It’s possible the OBD2 scanner itself is faulty. Try using the scanner on another OBD2 compliant vehicle to see if it functions correctly.
- Software/Firmware Issues: Outdated scanner software or firmware can sometimes cause communication problems. Check if your scanner requires updates and ensure it’s running the latest version.
- Incorrect Scanner Settings: Some advanced scanners have settings that need to be configured for specific vehicle types. Double-check your scanner’s manual to ensure you’re using the correct settings for your Toyota Innova.

Troubleshooting Steps:

Inspect the DLC Port: Visually check for damage or debris.
Try a Different Scanner: If possible, test with another OBD2 scanner, preferably a different brand or type.
Check Fuses: Locate and inspect the fuses related to the OBD system and PCM.
Verify Scanner Protocol Support: Confirm your scanner supports the OBD2 protocols used by Toyota vehicles (often CAN protocol in modern Innovas).
Consult Vehicle Documentation: Refer to your Toyota Innova owner’s manual or repair information for specific OBD2 system details.
Seek Professional Help: If basic troubleshooting fails, it’s advisable to consult a qualified mechanic or technician. They have professional-grade diagnostic tools and expertise to pinpoint the communication issue and address any underlying vehicle problems.

Glossary of Common Automotive Terms

To further enhance your understanding, here’s a glossary of many of the terms we’ve touched upon, and more, for your reference.

[Insert Glossary Content Here – Use relevant terms from the original list, prioritizing those related to diagnostics, OBD2, engine, emissions, and electrical systems. You don’t need to include every term if it makes the article too long. Aim for a helpful and focused glossary. Format it as a markdown list as in the original, or consider grouping terms by category for better readability if appropriate for the article flow.]

Example of Glossary Entries (adapted from original, shortened for brevity and relevance):

ABS – Antilock Brake System
ACC – Air Conditioning Clutch
ACT – Air Charge Temperature sensor or signal circuit.
Actuator – A device that moves or controls another device in response to an electrical input.
AFC – Air Flow Control
AFM – Air Flow Meter
AFR – Air Fuel Ratio
AFS – Air Flow Sensor
AIR – Secondary air injection
AIS – Automatic Idle Speed
AIS (AUTOMATIC IDLE SPEED) MOTOR – Increases or decreases the size of an idle air bypass to raise or lower idle speed.
ALDL – Assembly Line Data Link
ALT – Alternator
ALTERNATING CURRENT (AC) – An electrical current which alternates it’s direction of flow at regular intervals.
AMMETER – A device which measures current in an electrical circuit.
AMPERE – A unit of measurement to determine the current in a circuit.
ANALOG – A method of transmitting information by varying a voltage or current.
ANALOG-DIGITAL (A-D) CONVERTER – An electronic circuit which converts an analog input to a digital output.
APS – Atmospheric Pressure Sensor
ARMATURE – The moveable part of an electromagnetic device.
ASR – Acceleration Slip Regulation
ATC – Automatic Temperature Control
ATDC – After Top Dead Center
ATF – Automatic Transmission Fluid
ATM – Actuator Test Mode
AUTOMATIC SHUT-DOWN RELAY – Operates under control of the vehicle’s on-board computer to supply voltage to fuel pump, ignition coil and fuel injectors.
AVAILABLE VOLTAGE – The amount of voltage measured at the voltage source.
AVOM – Analog Volt/Ohm Meter.
AWD – All-Wheel Drive
AXOD – Automatic Overdrive transaxle.
B+ – Battery Positive Voltage
BARO – Barometric Pressure
BAT – Battery
BATTERY – A group of two or more chemical cells connected together for the production of an electric current.
BATTERY VOLTAGE – The voltage measured between the two terminals of a battery.
BCM – Body Computer Module.
BEFORE TOP DEAD CENTER (BTDC) – Refers to crankshaft position relative to the ignition timing in degrees.
BLM – Block Learn Multiplier
BMAP – Barometric/Manifold Absolute Pressure Sensor
BOO – Brake On-Off input to the computer.
BOOST – Condition of over-pressure in the intake manifold.
BP – Barometric Pressure sensor.
BPP – Brake Pedal Position Switch
BPS – Back Pressure Sensor
BPT – Back-Pressure Transducer
BTDC – Before Top Dead Center
BTS – Battery Temperature Sensor
BUS P – Bus Positive
C – Celsius
C.A.R.B. – California Air Resource Board
C3I – Computer Controlled Coil Ignition.
CAC – Charge Air Cooler
CANISTER – A charcoal-filled container in an evaporative emission control system which traps vapors from the fuel system.
CANISTER PURGE CONTROL VALVE (CPCV) – A vacuum-operated valve which controls the flow of vapors from the canister to the engine.
CANP – EVAP Canister Purge Solenoid
CAPACITOR – A device capable of storing an electric charge.
CARB – Carburetor
CAS – Crank Angle Sensor
CATALYTIC CONVERTER – Muffler like assembly placed in exhaust system that contains a catalyst to change hydrocarbons and carbon monoxide into water vapor and carbon dioxide.
CC – Catalytic Converter
CC – Cruise Control
CC – Cubic Centimeters
CCC – Computer Command Control System
CCD – Chrysler Collision Detection
CCD BUS – A communication line used by various on-board computers for the transmission of data.
CCM – Central Control Module
CCM – Continuous Component Monitor
CCO – Converter Clutch Override
CCP – Controlled Canister Purge
CCRM – Constant Control Relay Module
CCS – Coast Clutch Solenoid
CCV – Canister Control Valve
CDI – Capacitor Discharge Ignition
CE – Commutator End
CEC – Crankcase Emission Control System
CECU – Central Electronic Control Unit
CEL – Check Engine Light
CENTRAL FUEL INJECTION – Computer control fuel injection at throttle body.
CFI – Central Fuel Injection
CFM – Cubic Feet Per Minute
CHARGE – Any condition where electricity is available.
CHARGE TEMPERATURE SENSOR – A thermistor located in the intake manifold.
CHECK ENGINE LIGHT – Instrument panel light used to aid in diagnosis of malfunctions.
CHECK VALVE – A one-way valve which allows vacuum or gas flow in one direction only.
CID – Cubic Inch Displacement
CID – Cylinder Identification sensor or its circuit.
CIRCUIT – An arrangement of conductors and components through which current can flow.
CIRCUIT BREAKER – A device which interrupts current flow in a circuit under abnormal conditions.
CIS – Continuous Injection System
CKP – Crankshaft Position Sensor
CKT – Circuit
CL – Closed Loop
CLC – Converter Lockup Clutch
CLCC – Closed Loop Carburetor Control
CLNT – Coolant
CLOSED CIRCUIT – An uninterrupted path beginning at the current source and returning to the current source.
CLOSED LOOP – A circuit in which the output of an electronic control is measured by a sensor and is returned to the control.
CLV – Calculated Load Value
CMFI – Central Multi-port Fuel Injection
CMP – Camshaft Position Sensor
CO – Carbon Monoxide
CO2 – Carbon Dioxide
COC – Conventional Oxidation Catalyst
COMBUSTION CONTROL COMPUTER – A computer control system used on some models with electronic fuel injection to control fuel injection, spark timing and advance, idle speed, air injection switching, and fuel evaporation purging.
COMMON POINT – A terminal or connection where two parallel circuits or components are joined.
COMPUTER TIMING – Total spark advance in degrees before top dead center.
CONDENSER – A device capable of storing an electric charge.
CONDUCTOR – Any material capable of transmitting electricity.
CONNECTOR – A mechanical device used to connect the components of an electrical circuit together.
CONTINUITY – A condition where a circuit is closed or continuous between given points.
CONTINUOUS SELF-TEST – Continuous test of Ford EEC-IV system conducted whenever vehicle is in operation.
CONTROLLER – Generic name for an on-board solid state microcomputer which monitors engine conditions and controls certain engine functions.
COOLANT TEMPERATURE SENSOR (CTS) – A thermistor which provides varying voltage, in proportion to engine coolant temperature, to the vehicle’s on-board computer.
COOLANT TEMPERATURE SWITCH – An “ON-OFF” switch which measures the engine coolant temperature and transmits the information on to the vehicle’s on-board computer.
COP – Coil On Plug Electronic Ignition
CORE – The center conductor part of a wire.
CP – Canister Purge
CP – Crankshaft Position Sensor
CPI – Central Port Fuel Injection
CPS – Crankshaft Position Sensor. Provides the ECU with engine speed and crankshaft angle (position).
CPU – Central Processing Unit
Crankshaft Position Sensor – Provides the ECU with engine speed and crankshaft angle (position).
CRK – Cranking Signal
CROSS-CIRCUIT SHORT – A current flow path between the hot wires in two different circuits.
CRT – Cathode Ray Tube
CSC – Coolant Spark Control
CSE GND – PCM Case Ground
CSSA – Cold Start Spark Advance System
CTS – Coolant Temperature Sensor.
CTVS – Closed Throttle Vacuum Switch
CURB IDLE – Computer controlled idle rpm.
CURRENT – The movement of electrons through a conductor material.
CURRENT-LIMITING RESISTOR – A resistor in a circuit to which limits the current.
CV – Control Valve
CVCC – Compound Vortex Controlled Combustion System
CVR – Control Vacuum Regulator
CVS – Constant Volume Sampler
CYCLE – A complete alternation in an alternating current.
CYLINDER IDENTIFICATION SIGNAL (CID) – A signal generated by crankshaft timing sensor, used to synchronize ignition coils.
Data Output Line to IPC – Fuel calculation data from EEC-IV processor to trip computer.
DATA OUTPUT LINK (DOL) – Data Output Link. Fuel calculation data from EEC-IV processor to trip computer.
dB – Decibels
DC – Direct Current
DC – Duty Cycle
DCL – Data Communication Link
DDL – Diagnostic Data Link
DE – Drive End
DEAD SHORT – A short circuit having zero resistance.
DEC – Digital Electronic Controller
DE-ENERGIZED – The condition of an electrical circuit having the electric current or energy source turned off.
DEFI – Digital Electronic Fuel Injection
DEPS – Digital Engine Position Sensor
DERM – Diagnostic Energy Reserve Module and air bag controller.
DETONATION (KNOCK) SENSOR – A piezoelectric device which responds to spark knock and transmits this information to the vehicle’s on-board computer.
DFCO – Decel Fuel Cutoff Mode
DFI – Direct Fuel Injection
DI – Direct Ignition
DI – Distributor Ignition (System)
DIAGNOSTIC MODE – The mode of operation used by the vehicle’s on-board computer to transmit Fault Codes.
DIAGNOSTIC READ-OUT BOX (DRB) – The Chrysler Motors tester used to diagnose the on-board computer system.
DIAPHRAGM – A mechanical component which moves a control lever when a vacuum signal is applied.
DIC – Driver Information Center
DICM – Distributor Ignition Control Module
DID – Driver Information Display.
DIELECTRIC – The insulating material used between the plates of a capacitor or condenser.
DIGITAL CONTROLS – Circuits which process and/or transmit information by switching current on and off.
DIGITAL INJECTION – Cadillac brand name for Throttle body Fuel Injection.
DIGITAL VOLT-OHMMETER (DVOM) – A device which measures voltage and resistance in an electrical circuit. Readings are displayed in digital form on a liquid crystal display (LCD).
DIODE – An electronic component which allows current flow in one direction and blocks current flow in the opposite direction.
DIRECT CURRENT (DC) – Electrical current which flows in one direction only.
Direct Ignition (Waste Spark) – Produces ignition spark without aid of an ignition distributor.
DIRECT IGNITION SYSTEM (DIS) – Produces ignition spark without the aid of an ignition distributor.
DIS – Direct Ignition (Waste Spark)
DISTANCE (SPEED) SENSOR – Sensor is mounted at the transaxle tailshaft housing which transmits a signal representing vehicle speed to the vehicle’s on-board computer.
DISTRIBUTOR – A device which directs secondary current from the induction coil to the spark plugs of a multi-cylinder engine, in proper firing order.
DLC – Data Link Connector (OBD)
DOHC – Dual Overhead Cam
DOL – Data Output Line to IPC
DPFE – Differential Pressure Feedback
DRAW – The amount of electric current used by a load or circuit.
DRB II – Diagnostic Readout Box (Chrysler)
Drive Cycle – An extended set of driving procedures that takes into consideration the various types of driving conditions encountered in real life.
DRIVER – A transistor used to open and close the ground circuit of an output device.
Driving Condition – A specific environmental or operation condition under which a vehicle is operated.
DRL – Daytime Running Lights
DSO – Digital Storage Oscilloscope
DSR – Ford Diagnostic Subroutine
DSS – Downshift Solenoid
DSSA – Dual Signal Spark Advance
DTC FRZ – Diagnostic Trouble Code Freeze Frame
DTC(s) – Diagnostic Trouble Code(s)
DTM – Diagnostic Test Mode
DUTY CYCLE – The percentage of time that the vehicle’s on-board computer energizes a solenoid.
DVOM – Digital Volt-Ohmmeter
DWELL – Amount of time that current passes through a closed switch.
E4OD – Electronic 4-Speed Overdrive
EAC – Electronic Air Control
EACV – Electronic Air Control Valve
EAIR – Electronic Secondary Air Injection
EAS – Electronic Air Switching
EBCM – Electronic Brake Control Module
EBP – Exhaust Back :Pressure
EBTCM – Electronic Brake T/C Module
EC – Engine Control
ECA – Electronic Control Assembly. Ford’s engine controlling computer.
ECC – Electronic Climate Control
ECCS – Electronic Concentrated Control System
ECI – Extended Compressor at Idle
ECIT – Electronic Control Ignition Timing
ECL – Engine Coolant Level
ECM – Engine Control Module properly call a Powertrain Control Module.
ECS – Emission Control System
ECS – Evaporation Control System
ECT – Engine Coolant Temperature sensor or circuit.
ECU – Electronic Control Unit
EDF – Electro-Drive Fan relay or its circuit.
EDIS – Electronic Direct Ignition System
EDM – Electronic Distributor Modulator
EEC – Electronic Engine Control
EEC-IV – Electronic Engine Control design 4. A computer controlled system of engine control used on Ford. Control of Ignition Timing and Fuel Delivery Through an Electronic Fuel Injection System
EECS – Evaporative Emission Control System
EEGR – Electronic Exhaust Gas Recirculation valve
EEGR Monitor – Electronic EGR Test
EEPROM – Electronically Erasable Programmable Read Only Memory
EESS – Evaporative Emission Shed System
EET – Electronic Exhaust Gas Recirculation Transducer.
EFC – Electronic Feedback Carburetor
EFC – Electronic Fuel Control
EFE – Early Fuel Evaporation
EFI – Electronic Fuel Injection
EFT – Engine Fuel Temperature
EFV – Early Fuel Evaporation
EGC – Exhaust Gas Check Valve
EGO – Exhaust Gas Oxygen Sensor
EGOR – EGO Signal Return
EGR – Exhaust Gas Recirculation
EGR Monitor – OBDII EGR Test
EGRC – EGR Control Solenoid
EGRPS – EGR Valve Position Sensor
EGRT – Exhaust Gas Recirculation Temperature
EGTS – Exhaust Gas Temperature Switch
EH – Electro-Hydraulic
EHC – Exhaust Heat Control vacuum solenoid or its circuit.
EI – Integrated Electronic Ignition System
EIC – Electronic Instrument Cluster.
EICV – Electronic Idle Control Valve
ELB – Electronic Lean Burn
ELC – Electronic Level Control
ELCD – Evaporative Loss Control Device
ELECTRIC FUEL PUMPS – Two electric fuel pump systems are used by Chrysler Motors vehicles: a high-pressure in-tank pump is used for certain high-pressure fuel injection systems, and a low-pressure in-tank pump is used for low-pressure fuel injection systems.
ELECTROMAGNETIC – A device which utilizes electronic and magnetic principles in its composition and operation.
ELECTROMECHANICAL – A device which utilizes electronic and mechanical principles in its composition and operation.
ELECTRONIC – Term used to describe an arrangement of conductors, semiconductors, and other components which accomplishes the control of system or devices through the use of electrical signals.
Electronic Control Unit – Processes input information to trigger ignition control module.
Electronic Feedback Carburetor – Utilizes an electronic signal, generated by an exhaust gas oxygen sensor to precisely control air/fuel mixture ratio in the carburetor.
ELECTRONIC FUEL CONTROL – A computer control system was introduced on 1981 front wheel drive vehicles to control fuel and ignition systems through six sub-systems.
Electronic Fuel Injection – Electronic Fuel Injection. Computer controlled fuel injection system.
ELECTRONIC SPARK ADVANCE (ESA) – An electronic ignition system, under control of the vehicle’s on-board computer, which controls ignition timing and spark advance.
ELECTRONIC SPARK CONTROL – Used to retard spark advance if detonation occurs.
ELECTRONIC SPARK CONTROL (ESC) – A redesigned version of the ELB electronic ignition system.
ELECTRONIC SPARK TIMING – PCM controlled timing of the ignition spark.
EM – Engine Modification
EMF – Electromotive Force (voltage)
EMI – Electromagnetic Interference
EMR – Electronic Module Retard, controls spark retard.
EN – Generator (Alternator)
Enabling Criteria – A specific set of “conditions” or “driving procedures” must be met before the computer can command a Monitor to run tests on its related system.
ENERGIZED – The condition of an electrical circuit having the electric current or source turned on.
ENGINE CONTROL MODULE – A microprocessor based device which contains electronic circuitry to control and monitor air/fuel and emission systems, and aid in diagnostics.
ENGINE CONTROL SYSTEM – A computer control system first used on 2.2L electronic throttle body fuel injected (TBI) vehicles to control fuel, ignition, and emission control systems through six sub-systems.
ENGINE RUNNING TEST MODE – The diagnostic mode used to read the output signals of specific sensors to the vehicle’s on-board computer when the engine is idling.
EOBD – European On Board Diagnostics
EOP – Engine Oil Pressure
EOS – Exhaust Oxygen Sensor
EOT – Engine Oil Temperature
EP – Exhaust Pressure
EPA – Environmental Protection Agency
EPC – Electronic Pressure Control
EPROM – Erasable Programmable Read Only Memory.
EPT – EGR Pressure Transducer
ER – Engine running, used on some Ford system tests.
ERS – Engine RPM Sensor.
ESA – Electronic Spark Advance
ESC – Electronic Spark Control System
ESD – Electrostatic Discharge
ESS – Electronic Spark Selection
EST – Electronic Spark Timing
ETC – Electronic Temperature Control
ETP – EGR Pressure Transducer
EVAP – Evaporative Emissions System
EVAP CP – Evaporative Canister Purge
EVAP CV – Evaporative Emissions System Canister Vent
EVIC – Electronic Vehicle Information Center
EVO – Electronic Vehicle Orifice
EVP – EGR Valve Position sensor or its circuit.
EVR – EGR Vacuum Regulator or its circuit.
EXH – Exhaust
EXHAUST GAS OXYGEN SENSOR – Sensor that changes its voltage output as exhaust gas oxygen content changes as compared to oxygen content of the atmosphere.
Exhaust Gas Recirculation – A procedure in which inert exhaust gases are recirculated to the combustion chamber to cool combustion temperatures and reduce nitrous oxides in exhaust.
EXHAUST GAS RECIRCULATION – Procedure where a small amount of exhaust gas is readmitted to combustion chamber to reduce peak combustion temperatures, thus reducing NOx.
EXHAUST HEAT CONTROL VALVE – A valve which routes hot exhaust gases to the intake manifold heat riser during cold engine operation.
F.I. – Fuel Injection
FAIL SAFE – or Fail Soft: any attempt by a computer to compensate for a fault or lost signal, usually by substituting fixed replacement valves.
FAULT CODES – A series of two-digit numbers, stored in the vehicle’s on-board computer, which represent the results of On-Board Diagnostics or Vehicle Diagnostics.
FBC – Feedback Carburetor
FC – Fan Control
FCA – Fuel Control Assembly
FCS – Fuel Control Solenoid
FDBK – Feedback
FEED CIRCUIT – The power supply or hot wire.
FEEDBACK CARBURETOR (FBC) – System of fuel control employing a computer controlled solenoid that varies the carburetors air/fuel mixture.
FEEDBACK CARBURETOR ACTUATOR – Computer controlled stepper motor used on Ford feedback carburetors, that varies air/fuel mixture.
FEEPROM – Flash Electronically Erasable Programmable Read Only Memory
FEPROM – Flash Erasable Programmable Read Only Memory
FF – Flexible Fuel
FI – Fuel Injector
FIC – Fast Idle Control
Filtered Tachometer Output – An output from Ford DIS TFI IV module which provides a filtered ignition signal to the processor in order to control dwell.
FIPL – Fuel Injection Pump Lever
FLC – Fluid Lock-up Converter
FLS – Fluid Level Sensor
FM – Fan Motor Program in PCM
FMEM – Failure Mode Effects Management. Sometimes referred to limp-in mode.
FOM – Fix Operating Mode (Limp Mode)
FP – Fuel Pump
FPM – Fuel Pump Monitor (in PCM)
FRC – Forced
Freeze Frame – A digital representation of engine and/or emissions system conditions present when a fault code was recorded.
FREQUENCY – The number of cycles-per-second of an alternating current.
FRP – Fuel Rail Pressure
FRZ – Freeze Frame
FT – Fuel Trim
FTP – Fuel Tank Pressure
FUEL FILTER – A device installed in the pressure line to prevent foreign particles from entering the remainder of the fuel system.
FUEL INJECTOR – An assembly which receives a metered charge of fuel from another source, and is actuated by an engine mechanism to inject the charge of fuel into the combustion chamber at the proper time.
FUEL PRESSURE (INLET) LINE – The pressurized line, which carries the fuel supply from the fuel tank to the fuel pump and the fuel injectors.
FUEL PRESSURE REGULATOR – A device which maintains a controlled fuel pressure at the fuel injector or a controlled differential pressure across the fuel injector.
FUEL PUMP – A device which provides a specified fuel flow at the required system pressure.
FUEL PUMP RELAY – Provides power to the electric fuel pump in TBI/EFI systems.
FUEL RAIL – A fuel manifold line which carries and distributes the fuel to the individual injectors.
FUEL RETURN LINE – The line which carries unused fuel from the fuel rail or throttle body back to the fuel tank.
FUEL RICH, LEAN – An evaluation of the air/fuel ratio based on the input received from the oxygen sensor.
FUEL SYSTEM INERTIA SWITCH – A device used in most Ford vehicles which acts as a circuit breaker for the fuel system’s electrical components.
FUEL SYSTEM TEST PORT – A test port or opening incororated in the fuel rail or throttle body specifically designed to provide easy access to test and clean the fuel system.
FUEL TANK – A holding apparatus, which stores the vehicle’s fuel supply.
FUEL-VACUUM SEPARATOR – A filtering device which protects the vacuum delay and distributor vacuum controls by removing hydrocarbons from carburetor-ported vacuum.
FUSE – A mechanical device which contains a soft piece of metal which opens (melts) and breaks the circuit during high current (overload) conditions.
FUSIBLE LINK – A device which protects a circuit from damage if a short to ground occurs, or if the polarity of the battery (or charger) is reversed.
FWD – Front Wheel Drive
g/sec – Grams per Second
GA – Gage
GCM – Governor Control Module
GDC – Fuel Data Center
GDI – Gasoline Direct Injection
GEM – Generic Electronic Module
GEN – Generator (Alternator)
GENERATE – To produce electricity by the process of electromagnetic induction.
Generic Code – A DTC that applies to all OBD 2 compliant vehicles.
GND – Electrical Ground Connection
GOOSE – Brief Throttle Open/Close
GPM – Grams Per Mile
GPS – Governor Pressure Sensor
GROUND (OR GND) – In automotive applications, the common line leading to the negative side of the battery.
GROUND-SIDE SWITCH – A switch located in the ground side of a circuit instead of the hot wire.
GST – Generic Scan Tool
GVW – Gross Vehicle Weight
H – Hydrogen
HAC – High Altitude Compensator
HALL EFFECT – Process where current is passed through a small slice of semiconductor material at the same time as a magnetic field to produce a small voltage in the semiconductor.
HARD FAULT – Fault present during current engine operating cycle. Opposite of an intermittent fault which does not stay present.
HARD FAULT CODE – A circuit or component failure that reappears after codes have been cleared and the system has been retested.
HBV – Heater Blower Voltage
HC – Hydrocarbons
HCDS – High Clutch Drum Speed
HCV – Hydrocarbon
HD – Heavy Duty
HDC – Heavy Duty Cooling
HDR-CKP – High Data Rate CKP Sensor
HEATED OXYGEN SENSOR (HO2S) – The heated oxygen sensor monitors the oxygen content of the vehicle’s exhaust gases, and generates a voltage signal (representing the air/fuel ratio) used by the vehicle’s on-board computer for fuel control.
Heater Blower Voltage – Heater Blower Voltage input to EEC-IV processor reflecting heater blower voltage demand.
HEGO – Heated Exhaust Gas Oxygen Sensor
HEI – High Energy Ignition
HFC – High (speed) Fan Control
HFP – High Fuel Pump (Relay) Control
Hg (MERCURY) – A material used as a calibration standard for vacuum measurement.
HIC – Hot-Idle Compensator
HIGH TENSION SECONDARY VOLTAGE – Voltage which enables current to jump the spark plug gap.
HIGH-RESISTANCE SHORT – A short circuit which draws a slow current.
HO – High Output
HO2S – Heated Oxygen Sensor
HO2S-1-1 – Bank One Sensor One Signal
HO2S-2-1 – Bank Two Sensor One Signal
hp – Horsepower
HPC – High Pressure Cutoff
HPL – High Pressure Liquid
HPS – High Performance System
HPV – High Pressure Vapor
HSC – High Swirl Combustion
HT – High Tension
HUD – Heads Up Display
HVAC – Heater Ventilation and Air Conditioning
HVACM – Heater-Vent-Air Conditioning Module
HVS – High Voltage Switch
Hz – Hertz
I/M – Inspection and Maintenance
I/M Readiness – An indication of whether or not a vehicle’s emissions-related system are operating properly and are ready for Inspection and Maintenance testing.
I/M Test / Emissions Test / Smog Check – A functional test of a vehicle to determine if tailpipe emissions are within Federal/State/Local requirements.
I/O – Input / Output
I/P – Instrument Panel
IA – Intake Air
IAC – Idle Air Control (motor or solenoid)
IACV – Idle Air Control Valve
IAT – Intake air temperature sensor, performs same function as MAT sensor.
IBP – Integral Back Pressure
IC – Ignition Control
IC – Integrated Circuit
ICM – Ignition Control Module
ICP – Injection Control Pressure
ICS – Idle Control Solenoid
ID – Inside Diameter
IDI – Integrated Direct Ignition
IDL – Idle Position Switch
Idle Speed Actuator – Extends or retracts to control engine idle speed and to set throttle stop angle during deceleration.
Idle Speed Control – Idle Speed Control, either computer control motor, air bypass valve, or any device used to control idle rpm.
IDLE SPEED STEPPER (ISS) MOTOR – The ISS motor controls airflow inside the throttle body bypass passage to control idle speed.
IDLE TRACKING SWITCH – An input device that sends a signal to the computer to indicate a closed throttle condition.
IDM – Ignition Diagnostic Monitor
IDM – Injector Driver Module
IFI – Indirect Fuel Injection
IFS – Inertia Fuel Switch
IGN – Ignition
IGN ADV – Ignition Advance
IGN GND – Ignition Ground
Ignition Diagnostic Monitor – Continuous monitor of ignition input to EEC-IV processor used to detect intermittent ignition faults.
ILC – Idle Load Compensator
IMA – Idle Mixture Adjuster
IMPEDANCE – The total opposition of a circuit to the flow of alternating current, measured in ohms (includes resistance and reactance).
IMRC – Intake Manifold Runner Control
IMS – Ignition Module Signal
IMT – Intake Manifold Timing
INDUCTION – The process of magnetizing and object, or of inducing a voltage in an object by placing it within a magnetic field.
INJ 1 to INJ 10 – Fuel Injectors 1 to 10
INJECTOR – A fuel injection system electrical solenoid which, when energized, allows fuel flow into the intake manifold where it is mixed with air for combustion.
INPUTS – Information, in the form of a voltage or current, from a device external to the vehicle’s on-board computer which assists the computer in monitoring and maintaining engine performance.
INSULATOR – Any material which will not conduct current.
INT – Integrator
INTERMITTENT – Occuring infrequently (not continuously) and usually on an irregular basis.
INTERMITTENT FAULT – Fault which occurred during a previous engine operating cycle.
IPC – Instrument Panel Cluster
IPR – Injector Pressure Regulator
IRCM – Integrated Relay Control Module
ISA – Idle Speed Actuator
ISC – Idle Speed Control
ISO – International Standard of Organization
ISS – Input Shaft Speed
ITA – Ignition Timing Adjustment
ITCS – Ignition Timing Control System
ITS – Idle Tracking Switch
IVS – Idle Validation Switch
IVSC – Integrated Vehicle Speed Control
IVV – Idle Vacuum Valve
JAS – Jet Air System
JSV – Jet Mixture Solenoid Valve
KAM – Keep Alive Memory
KAPWR – Direct Battery Power, used to power KAM circuit of the processor.
KD – Kickdown
KDLH – Kickdown Low Hold
Keep Alive Memory – Battery power memory locations in computer used to store failure codes and some diagnostic parameters.
kHz – Kilohertz
Km – Kilometers
KNOCK SENSOR (KS) – Input device that responds to spark knock, caused by over advanced ignition timing.
KOEC – Key On, Engine Cranking
KOEO – Key On, Engine Off
KOER – Key On, Engine Running
KPA – Kilopascal
KS – Knock Sensor
KSM – Knock Sensor Module
L – Liters
L4 – Four Cylinder Inline Engine
LAB OSCILLOSCOPE – An electronic device used to analyze voltages.
LAMBSE – Short Term Fuel Trim
LCD – Liquid Crystal Display
LEAN MIXTURE – Air/fuel mixture that has excessive oxygen left after all fuel in combustion chamber has burned, 1 part fuel to 15 or more parts air.
LED – Light Emitting Diode
LFC – Low Fan Control
LFP – Low Speed Fuel Pump Control
LHD – Left Hand Drive
LIGHT-EMITTING DIODE (LED) – A positive/negative junction of crystal which produces light when forward bias current is applied.
LIMP-IN MODE – A condition where the vehicle’s on-board computer has detected a faulty or failed input device and has substituted a known value for the failed input.
LINEAR – A mathematically expressed relationship, the graphical representation of which is a straight line.
LOAD – Calculated Load Value
LOC – Light Off Catalyst
LOCK UP TORQUE CONVERTER – Converter with internal mechanism that locks turbine to impeller when engaged.
LOCK-UP TORQUE CONVERTER SOLENOID – A transaxle-mounted solenoid, operating under control of the vehicle’s on-board computer, which engages the torque converter to directly connect the engine to the transaxle.
LOGIC MODULE – A microprocessor which receives inputs from the vehicle’s engine control system sensors, and generates the output signals to control engine operation an an optimum balance between engine performance, vehicle emissions and fuel economy.
LOGIC PROBE – A device used to verify operation of a logic (on/off) circuit.
Long Term Fuel Trim – A program in the vehicle’s computer designed to add or subtract fuel from the vehicle to compensate for operating conditions that vary from the ideal A/F ratio (long term).
LONGFT – Long Term Fuel Trim
LOOP – Engine Operating Loop Status
LOS – Limited Operating Strategy
LPG – Liquid Petroleum Gas
LSS – Linear Shift Solenoid
LTFT – Long Term Fuel Trim
LTS – Low Coolant Switch
LUS – Lock-Up Solenoid
LV8 – Load Variable
LWB – Long Wheel Base
M/C – Mixture control or mixture control solenoid.
M/T – Manual Transmission
MAF – Mass Air Flow Sensor
MAF RTN – Mass Airflow Sensor Ground
MAGNETIC FIELD – The portion of space near a magnetic body in which magnetic lines of force exist.
MAGNETIC PICK-UP COIL – Coil used in electronic distributor ignition systems to determine when to switch off the coil secondary.
MAGNETIC RELUCTANCE – The opposition of a magnetic substance to the flow of magnetic flux through it.
MALFUNCTION – A problem which causes a system to operate incorrectly.
MALFUNCTION INDICATOR LIGHT (MIL) – Generic term for various warning lamps used to indicate malfunctions in the vehicle’s engine management system.
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR – A sensor which sends a varying frequency signal (based on manifold vacuum and manifold pressure) to the vehicle’s on-board computer for calculation of barometric pressure.
Manufacturer Specific Code – A DTC that applies only to OBD 2 compliant vehicles made by a specific manufacturer.
MAP – Manifold Absolute Pressure sensor or its circuit.
MAS – Mixture Adjust Screw
Mass Air Flow Sensor – Used to measure amount of airflow through the throttle body.
MAT – Manifold Air Temperature.
MC – Mixture Control
MCS – Mixture Control Solenoid
MCT – Manifold Charge Temperature Sensor
MCU – Microprocessor Control Unit
MCV – Manifold Control Valve
MDP – Manifold Differential Pressure
MECS – Mazda Electronic Control System
MEMCAL – Memory Calibration
MERCURY (Hg) – A material used as a calibration standard for vacuum measurement.
MFI – Multi-port Fuel Injection.
MIC – Mechanical Instrument Cluster
MICROPROCESSOR – A small processor located in the vehicle’s computer.
MICROPROCESSOR CONTROL UNIT (MCU) – The controlling computer, used on early Ford feedback carburetor systems and all 5.8L feedback carburetor equipped Fords.
MIL – Malfunction Indicator Lamp (also referred to as “Check Engine” light
MISAR – Microprocessed Sensing and Automatic Regulation
MIXTURE CONTROL SOLENOID – Device installed on carburetor, that regulates the air/fuel ratio.
MLP – Manual (shift) Lever Position sensor or its circuit.
MLUS – Modulated Lock Up Solenoid or its Control Circuit
MLVLPS – Manual Valve Lever Position
MODE – A specific state or condition of operation.
MODULE – A mechanical, electrical or electromechanical arrangement of components intended to perform a specific task (such as ignition).
Monitor – Monitors are “diagnostic routines” programmed into the PCM.
Monitor Has/Has Not Run – The terms “Monitor has run” or “Monitor has not run” are used throughout this manual.
MPFI – Multi-Port Fuel Injection
MPG – Miles Per Gallon
MPH – Miles Per Hour
MPI – Multi Port Injection
mS or ms – Millisecond
MSFF – Miles Since First Fail
MSLF – Miles Since Last Fail
MST – Manifold Surface Temperature
MT – Manual Transmission
MTV – Manifold Tune Valve
MULTI-PORT FUEL INJECTION – Individual injectors for each cylinder mounted in intake manifold.
mV or mv – Milivolt
MVLPS – Manual Valve Lever Position
MVZ – Manifold Vacuum Zone
N – Nitrogen
N.C. – Normally Closed Position
N.O. – Normally Open Position
N/MIL – A Code Set Without a MIL Request
NDIR – Non Dispersive Infrared
NDS – Neutral Drive Switch.
NEUTRAL/SAFETY SWITCH – A switch which signals the vehicle’s on-board computer that the automatic transaxle is in neutral.
NGS – Neutral Gear Switch or its circuit.
NGV – Natural Gas Vehicles
Nm – Newton Meters
NON-VOLATILE MEMORY – Memory retained in block learn cells.
NOx – Oxides of Nitrogen
NPS – Neutral Pressure Switch or its circuit.
NTC – Negative Temperature Coefficient
NVRAM – Non Volatile Random Access Memory
O2 – Oxygen
O2 (OXYGEN) SENSOR – The oxygen sensor monitors the oxygen content of the vehicle’s exhaust gases and generates a voltage signal (representative of the air/fuel ratio) used by the vehicle’s on-board computer for fuel control.
O2S-11 – Oxygen Sensor Signal (Bank 1)
O2S-21 – Oxygen Sensor Signal (Bank 2)
OASIS – Ford Motor Company Online Automotive Service Information System
OBD (ON-BOARD DIAGNOSTICS) – Refers to the self-testing ability of the vehicle’s on-board computer which allows the computer to verify its own operational ability.
OBD 1 – On-Board Diagnostics Version 1
OBD 2 – On-Board Diagnostics Version 2
OBD 2 Drive Cycle – An OBD 2 Drive Cycle is an extended set of driving procedures that takes into consideration the various types of driving conditions encountered in real life.
OBD I – On Board Diagnostics Version I
OBD II – On Board Diagnostics Version II
OBD STAT – On Board Diagnostic System Status
OC – Oxidation Catalytic Converter
OCC – Output Circuit Check
OCIL – Overdrive Cancel Indicator Lamp
OCS – Overdrive Cancel Switch
OCT ADJ – Octane Adjust device which modifies ignition spark.
OD – Overdrive
ODM – Output Device Monitor
ODS – Overdrive Drum Speed
OE – Original Equipment
OEM – Original Equipment Manufacturer
OHC – Overhead Cam Engine
OHM – Unit of electrical resistance.
OHV – Over Head Valve
OL – Open Loop
On-Board Computer – The central processing unit in the vehicle’s computer control system.
OPEN CIRCUIT – A circuit which does not provide a complete path for the flow of current.
ORC – Oxidation Reduction Converter
OS – Oxygen Sensor
OSAC – Orifice Spark Advance Control
OSC – Output State Check
OSCILLOSCOPE – A test instrument used to analyze an electronic circuit.
OSM – Output State Monitor
OSS – Output Speed Shaft
OTIS – Overhead Travel Information System
OVCV – Outer Vent Control Valve
P/B – Power Brakes
P/E – Power Enrichment
P/N – Part Number
P/S – Power Steering
PA – Pressure Air
PAIR – Pulsed Secondary Air Injection
PARALLEL CIRCUIT – A circuit in which there are two or more paths for current flow.
PAS – Power Assisted Steering
PASS – Personalized Automotive Security System
PC – Pressure Control
PCB – Printed Circuit Board
PCM – Powertrain Control Module
PCM (POWERTRAIN CONTROL MODULE ) – Generic term used to refer to the arrangement controllers/computers which control the engine management system, emissions systems, and the shift operations of automatic transmissions.
PCS – Pressure Control Solenoid
PCV – Positive Crankcase Ventilation
PCV (POSITIVE CRANKCASE VENTILATION) – A system which vents vapors from the crankcase into the engine intake system where they are burned in the engine cylinders rather than being discharged in the exhaust gases.
Pending Code – A code recorded on the “first trip” for a “two-trip” code.
PF – Purge Flow Sensor
PFE – Pressure Feedback EGR sensor or its circuit.
PFI – Port Fuel Injection
PGM-FI – Programmed Gas Management Fuel Injection
PID – Parameter Identification
PIP – Profile Ignition Pickup.
PIV – Peak Inverse Voltage
PKE – Passive Keyless Entry
PMD – Pump Mounted Driver
PNP – Par Neutral Position
PORTED VACUUM SWITCH – Temperature actuated switch that changes vacuum connections when the coolant temperature changes.
POT – Potentiometer
POTENTIOMETER (POT) – A variable resistor with three connections.
POWER LOSS LAMP – Term for the instrument panel-mounted lamp on early Chrysler vehicles (functions the same as the Check Engine Light).
POWER MODULE – A microprocessor which delivers commands from the on-board computer’s Logic Module to the various actuators in the vehicle’s engine control system.
Power Steering Pressure Switch – Signal is used by computer to compensate for power steering loads.
POWERTRAIN CONTROL MODULE (PCM) – Same as ECM, but also controls electronically controlled automatic transmission. The PCM is the OBD 2 accepted term for the vehicle’s “on-board computer.”
PPM – Parts Per Minute
PPS – Ported Pressure Switch
PR – Pressure Relief
PRC – Pressure Regulator Control
PRESSURE REGULATOR – A device which controls the pressure of the fuel delivered to the fuel injector(s).
PRIMARY WINDING – The low voltage winding of the ignition coil which is electronically connected to its secondary winding only by the magnetic field they share.
PROM – Programmable Read Only Memory.
PS – Power Steering
PSA – Pressure Switch Assembly
PSC – Power Steering Control
PSI – Pounds Per Square Inch
PSOM – Programmable Speedometer Odometer Module
PSP – Power Steering Pressure
PSPS – Power Steering Pressure Switch
PTC – Positive Temperature Coefficient Resistor
PTOX – Periodic Trap Oxidizer
PTU – Part Throttle Unlock
PULSE – An abrupt change in a voltage either (positive or negative).
PVA – Ported Vacuum Advance
PVS – Ported Vacuum Switch
PWM – Pulse Width Modulation
PWR GND – Power Ground for PCM
QDM – Quad Driver Module
QUICK TEST – A functional diagnostic test for Ford EEC-IV system, consisting of test hookup, key on engine off, engine running and continuous self test models.
RABS – Rear Antilock Brake System
RAM – Random Access Memory
RAP – Retained Accessory Power.
RATIO – The relationship in quantity, amount or size between one value and another.
RECAL – Calibration Adjustment
REDOX – Reduction Oxidation Converter
REF – Reference
REFERENCE VOLTAGE (VREF) – Regulated voltage provided by the vehicle’s computer to some vehicle sensors.
RELAY – Switching device operated by a low current circuit, which controls opening and closing of another higher current circuit.
RELIEF VALVE – Pressure limiting valve located in exhaust chamber of thermactor air pump.
RESISTANCE – The property of a device or circuit which causes it to oppose the movement of current through it. The unit of electrical resistance is the ohm.
RESISTOR – An electronic component which restricts the flow of current.
REST PRESSURE – Fuel pressure maintained within the fuel system after the engine is turned off.
RFI – Radio Frequency Interference
RHD – Right Hand Drive
RICH MIXTURE – Air/fuel mixture that has more fuel than can burn completely, 1 part fuel to 14 or less parts air.
RKE – Remote Keyless Entry
RM – Relay Module
ROM – Read Only Memory
RPM – Revolutions Per Minute
RRS – Variable Reluctance Sensor
RTD – Real Time Dampening
RTN – Dedicated Sensor Ground Circuit
RTV – Room Temperature Vulcanizing
RVP – Reid Vapor Pressure
RWAL – Rear Wheel Anti-Lock
RWD – Rear Wheel Drive
SAE – Viscosity Grade
SAVM – Spark Advance Vacuum Modulator
SAW – Spark Advance Word, and also Spark Angle Word.
SBDS – Service Bay Diagnostic System
SBEC – Single Board Engine Controller
SBS – Boost Solenoid
SBT – Serial Bus Traveler
SC – Super Charged
SCAP – Silicone Capacitance Absolute Pressure Sensor
SCB – Supercharger Bypass
SCC – Spark Control Computer.
SCP – Standard Corporate Protocol
SDI – Saab Direct Ignition
SDM – Sensing Diagnostic Module
SDV – Spark Delay Valve
SECONDARY WINDING – The winding of the ignition coil which supplies high tension current to the spark plugs.
SEFI – Sequential Electronic Fuel Injection
Self Test Input – Circuit in EEC or MCU systems. Used to place computer into testing mode.
Self Test Output – Self Test Output circuit in EEC or MCU systems. Used by computer to send testing and fault codes to tester.
SELF-TEST – One of 3 subsets of Ford EEC-IV quick test modes.
SENSOR – Any component which can detect and relay information relating to the operational status of a component or system.
SENSOR TEST MODE – The diagnostic mode used to check the output signal of specific sensor with the engine off.
SEO – Special Equipment Option
Sequential Electronic Fuel Injection – Injectors located in intake ports that inject fuel triggered by ignition timing.
Sequential Fuel Injection – Type of MFI with injectors pulsed individually based on engine firing order.
SERIES CIRCUIT – A circuit in which each component is attached, one end to the other, providing only one path for current flow.
SERVICE REMINDER INDICATOR (SRI) – Indicator light which informs the driver that the vehicle is due for service.
SES – Service Engine Soon
SFI – Sequential Fuel Injection
SHED – Sealed Housing Evaporative Determination System
Shift Indicator Lamp – Indicates to driver optimum time to shift gears.
SHO – Super High Output Engine
SHORT – A generally unintended (accidental) connection in an electrical circuit which shortens the electrical path, and, depending on its location in the circuit, causes increased current to flow.
SHRT FT – Short Term Fuel Trim
SHRTFT1 – Short Term Fuel Trim Bank 1
SIG RTN – Signal Return (sensor ground)
SIL – Shift Indicator Lamp
SINGLE BOARD ENGINE CONTROLLER – This computer system is used on some post-1989 3.0L engine-equipped Chrysler Motors vehicles.
SINGLE MODULE ENGINE CONTROLLER (SMEC) – This computer system is used on some post-1987 Chrysler Motors vehicles. The Logic Module and Power Module are housed in a common enclosure.
SIPS – Side Impact Protections System
SIR – Supplemental Inflatable Restraint (SIR) system; air bag.
SIS – Solenoid Idle Stop
SMEC – Single Module Engine Controller
SMPI – Sequential Multiport Fuel Injection
SO2 – Sulfur Dioxide
SOFT FAULT CODE – A circuit or component failure, recorded by the vehicle’s on board computer, that does not reappear after codes have been cleared and the system retested.
SOHC – Single Overhead Cam
SOLENOID – Wire coil with a movable core which changes position by means of electromagnetism when current flows through the coil.
SOLID STATE – Refers to circuits which use transistors, integrated circuits, and/or other semi-conductors.
SPARK ADVANCE – Causing spark to occur earlier.
Spark Output Signal – Spark output signal from EEC-IV processor to TFI-IV module, used to control amount of timing retard.
SPARK RETARD – Causing less spark advance to be added, resulting in a spark which is introduced later.
SPD – Speed
SPEED (DISTANCE SENSOR) – Sensor is mounted at the transaxle tailshaft housing which transmits a signal representing vehicle speed to the vehicle’s on-board computer.
SPFI – Single Point Fuel Injection (throttle body)
SPI – Serial Peripheral Interface
SPL – Smoke Puff Limiter
SPOUT – Spark Output Signal
SPS – Service Programming System
SRC – Selective Ride Control
SRDV – Spark Retard Delay Valve
SRI – Service Reminder Indicator
SRS – Supplemental Restraint System (air bag)
SRT – System Readiness Test
SS – Speed Sensor
SS1, SS2,etc. – Shift Solenoid 1, 2, etc.
SSI – Solid State Ignition system.
ST – Scan Tool
STAR – Self Test Automatic Readout
STFT – Short Term Fuel Trim, is a program in the vehicle’s computer designed to add or subtract fuel from the vehicle to compensate for operating conditions that vary from the ideal A/F ratio.
STI – Self Test Input
STO – Self Test Output
STOICHIOMETRY – In automotive applications, the air/fuel ratio resulting in optimum combustion.
STS – Service Throttle System (lamp)
SUSP – Suspension System Module
SVV – Solenoid Vent Valve
SWB – Short Wheel Base
T.V. – Throttle Valve.
TA – Temperature Air
TAB – Thermactor Air Bypass
TAC – Throttle Actuator Control
TACH – Tachometer
TACH INPUT – Engine rpm signal sent to computer from ignition coil primary circuit.
TAD – Thermactor Air Diverter solenoid.
TAP – Transmission Adaptive Pressure
TAV – Temperature Actuated Vacuum
TBI – Throttle Body Injection
TBI (THROTTLE BODY INJECTION) – Any one of several fuel injection systems which have the fuel injector(s) mounted in a centrally-located throttle body, rather than close to an intake port.
TC – Turbocharger
TCA – Thermostat Controlled Air Cleaner
TCC – Torque Converter Clutch
TCCP – Torque Converter Clutch Pressure
TCCS – Toyota Computer Controlled System
TCIL – Transmission Control Indicator Lamp
TCM – Transmission Control Module
TCP – Temperature Compensated Accelerator Pump
TCP – Torque Charger
TCS – Traction Control Switch
TCS – Transmission Control Switch
TCS – Transmission Controlled Spark
TD – Turbo Diesel
TDC – Top Dead Center
TDI – Turbo Direct Injection
TE – Thermal Expansion
TFI – Thick Film Ignition module. Controls coil and ignition operation on most Ford vehicles.
TFP – Throttle Fluid Pressure
TFP – Transmission Fluid Pressure
TFT – Transmission Fluid Temperature
THERMACTOR AIR BYPASS SOLENOID – Solenoid switches engine manifold vacuum.
THERMACTOR AIR CONTROL VALVE – Combines function of a normally closed air bypass valve and an air diverter valve in one integral valve.
THERMACTOR AIR DIVERTER SOLENOID – Solenoid switches engine manifold vacuum.
THERMACTOR AIR SYSTEM – Efficiency of catalytic converter is dependent upon temperature and chemical makeup of exhaust gases.
THERMISTOR – A variable resistor which changes its resistance in relation to ambient temperature.
THM – Turbo Hydra-Matic
THREE-WAY CATALYST – Combines 2 converters in 1 shell. Controls NOx, HC and CO. Also called dual catalytic converter.
THROTTLE POSITION SENSOR (TPS) – A variable resistance (potentiometer) sensor which senses position proportional to the throttle position.
TI – Transistorized Ignition System
TIC – Thermal Ignition Control
TIMING – Generally refers to relationship between spark plug firing and piston position.
TIV – Thermactor Idle Vacuum Valve
TK – Throttle Kicker Actuator
TK – Throttle Kicker solenoid, when energized, supplies manifold vacuum to throttle kicker actuator as directed by computer to compensate for engine loads. Also called idle-up system.
TKS – Throttle Kicker Solenoid
TOT – Transmission Oil Temperature
TP – Throttle Position sensor or its circuit. Used to signal computer the position of the throttle plates.
TP – Throttle Position
TP Mode – Throttle Position Mode
TPCV – Tank Pressure Control Valve
TPI – Tuned Port Injection
TPM – Tire Pressure Monitor
TPP – Throttle Position Potentiometer
TPS – Throttle Position Sensor
TPT – Throttle Position Transducer
TR – Transmission Range Sensor
TRANSDUCER – A device which is actuated by power from one system and supplies power (usually in another form) to a second system.
Trip – A Trip for a particular Monitor requires that the vehicle is being driven in such a way that all the required “Enabling Criteria” for the Monitor to run and complete its diagnostic testing are met.
Trip Drive Cycle – Vehicle operation that provides the necessary driving condition to enable a vehicle Monitor to run and complete its diagnostic testing.
TRLHP – Thermal Vacuum Valve
TRS, TRS+1 – Transmission Regulated Spark Control System
TSB – Technical Service Bulletin
TSP – Throttle Solenoid Positioner
TSS – Transmission Shaft Speed Sensor
TSS – Turbine Speed Shaft Sensor
TTS – Transmission Temperature Switch.
Tuned Port Injection – A type of MFI with intake tubes designed to be tuned for performance.
TV – Throttle Valve
TVS – Temperature Vacuum Switch.
TVV – Thermal Vent Valve
TWC – Three Way Catalyst
TWC – Three-Way Catalyst.
UART – Universal Asynchronous Receiver-Transmitter
UD – Underdrive
UIDI – Up-Integrated Direct Ignition
UP-SHIFT LIGHT – An indicator, primarily controlled by engine speed and manifold vacuum, which provides a visual indication of when to shift to the next higher gear to obtain maximum fuel economy.
V – Volts
VAC – Vacuum
VACUUM – Describes a pressure that is less than atmospheric pressure; negative pressure.
VACUUM ADVANCE – A method of advancing ignition timing based on engine load conditions.
VACUUM CHECK VALVE (VCV) – A one-way flow control valve used to retain a vacuum signal in system after the vacuum source is gone.
VACUUM REGULATOR – A device which provides a constant vacuum output when vehicle is at idle, and switches to engine vacuum when the vehicle is at off idle.
VACUUM REGULATOR/SOLENOID – A regulator valve, under control of the vehicle’s on-board computer, which provides vacuum to the feedback carburetor.
VACUUM RETARD DELAY VALVE (VRDV) – Delays a decrease in vacuum at the distributor vacuum advance until the source of vacuum decreases.
VAF – Vane Air-Flow sensor or its circuit.
VAF – Volume Air Flow
VAT – Vane Air Temperature Sensor
VAT – Vane Air-Flow Temperature sensor.
VATS – Vehicle AntiTheft System
VBAT – Vehicle (system) Battery Voltage
VCC – Vacuum Cut Control Solenoid
VCM – Vehicle Control Module
VCRM – Variable Control Relay Module
VCTS – Vacuum Control Temperature Sensing Valve
VCV – Vacuum Control Valve
VDOT – Variable Displacement Orifice Tube
VDV – Vacuum Delay Valve
VDV – Vacuum Differential Valve
VECI – Vehicle Emission Control Information Decal
VEHICLE EMISSION CONTROL INFORMATION (VECI) – Factory specifications for servicing the vehicle’s emission system.
VF – Vacuum Fluorescent
VIM – Vehicle Interface Module
VIN – Vehicle Identification Number
VIS – Variable Induction System
VLCM – Variable Load Control Module
VM – Vane Meter or air flow meter.
VMV – Vacuum Modulator Valve
VMV – Vapor Management Valve (EVAP)
VNT – Variable Nozzle Turbocharger
VOLTAGE – The electromotive force that moves electrons through a conductor.
VOLUMETRIC EFFICIENCY – Volumetric efficiency is a combination between ideal and actual efficiency of an internal combustion engine.
VOTM – Vacuum Operated Throttle Modulator
VPWM – Variable Pulse Width Modulated
VPWR – Ignition Switched Power
VR – Voltage Regulator
VR/S – Vacuum Regulator/Solenoid
VRDV – Vacuum Retard Delay Valve
VREF – Reference Voltage (from PCM)
VRESER – Vacuum Reservoir
VREST – Vacuum Restrictor
VRIS – Variable Resonance Induction System
VRS – Variable Reluctance Sensor
VRV – Vacuum Regulator Valve
VSS – Vehicle Speed Sensor
VVA – Venturi Vacuum Amplifier
VVC – Variable Voltage Choke
VVV – Vacuum Vent Valve
W/B – Wheelbase
WAC – WOT A/C Cutout Relay
Warm-up Cycle – Vehicle operation after an engine off period where engine temperature rises at least 40℉ (22℃) from its temperature before starting, and reaches at least 160℉ (70℃).
WASTEGATE CONTROL SOLENOID – Controls the boost output on turbocharged engines.
WOT – Wide Open Throttle or Wide Open Throttle switch.
WOT – Wide Open Throttle
WOTV – Wide-Open Throttle Valve
WSS – Wheel Speed Sensor
WU OC – Warm Up Oxidation Catalytic Converter
WU TWC – Warm Up Three Way Catalytic Converter
ZONED VACUUM SWITCHES – 3 switches used on Ford MCU system that provides input signals to MCU, regarding engine load.

[End of Glossary]

Understanding these terms is the first step in tackling automotive diagnostics and repairs. Whether you’re dealing with a “OBD2 No Sup” issue on your Toyota Innova or simply trying to understand a mechanic’s report, this knowledge will empower you to be a more informed car owner. Visit carparteu.com for more in-depth guides and resources to help you keep your vehicle running smoothly.