Acronyms and Definitions
4V: Four valves per engine cylinder
ABS: Anti-Lock Brake System
ABS_STAT: ABS system status TCM received PID
A/C: Air Conditioning
A/CC: Air Conditioning Clutch
A/CCR: A/C Clutch Control Relay
A/CLPCS: A/C Low Pressure Cycling Switch
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)
ACFDS_B: Air Conditioning Full Demand Switch (for traction battery compartment)
ACFDS_P: Air Conditioning Full Demand Switch (for passenger compartment)
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.
ACRDV: A/C Refrigerant Distribution Valve Output
ACRDV_F: A/C Refrigerant Distribution Valve Output Fault
A/D: Analog-to-Digital. Analog-to-Digital signal conversion.
ADC: See ATDC.
Air/Fuel Ratio: Air-to-fuel mixture ratio. An air-to-fuel mixture that is 14.7:1 is also called stoichiometry.
Ambient Air Temperature: Temperature of the air surrounding an object
AMC: Active Mount Control
AMC_F: Active Mount Control Fault
Analog (Electrical/Electronic): An electrical signal that can obtain any value within the voltage limits of the signal.
APP, APP1, APP2, APP3: Accelerator Pedal Position 1, 2, 3
APPS, APPS1, APPS2, APPS3: Accelerator Pedal Position Sensor 1, 2, 3
ARB: Air Resource Board
ARPMDES: Desired engine speed TCM received PID
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 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.
BPO: Battery Power Off
BPO_Hz: Battery Power Off Frequency PID
BPP: Brake Pedal Position
BPS: Brake Pedal Switch/Speed Control Deactivation
BRAKE_LMP or BRKL: Brake Warning Lamp Status. Activates the brake warning lamp by applying voltage to the control line.
BSI: Brake Shift Interlock
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 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 volt signal used as a reference by certain sensors.
CAFE: Corporate Average Fuel Economy. A set of federal requirements and regulations which govern fuel economy standards.
CANVNT: Canister Vent
CAN: Controller Area Network
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
CCNT: Number of Stored and Pending DTCs
CD A through D: Coil Driver 1 through 4
Centralized Testing Facility: State government operation. Provides inspection/maintenance (IM) and safety inspections.
CGND: Case Ground. Provides a ground source for the PCM or ECU case.
CHT: Cylinder Head Temperature. Units are displayed in either degrees Fahrenheit or Celsius.
CHTV: Cylinder Head Temperature Voltage
CKP: Crankshaft Position
CKP_SHLD: Crankshaft Position Shield
CKP+, CKP-: CKP+ is the crankshaft position (CKP) sensor signal wire. CKP- is the signal return.
CL: Closed Loop. An operating condition or mode which enables operation based on sensor feedback.
CMP: Camshaft Position. PCM input signal from the camshaft position sensor.
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 stabilizes.
CONT: Continuous Memory. The portion of keep alive memory (KAM) used to store DTCs generated during the continuous memory self-test.
CONTACT: Traction battery contactor status TCM received PID
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 Switch: Clutch Pedal Position Switch. Located on the clutch pedal and detects when the clutch pedal is pressed.
CQIS: Common Quality Indicator System
CRK_T: Time since engine started PID
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
DC: 1. Direct Current. Electric current flowing in 1 direction. 2. Duty Cycle. The voltage measurement of ON time versus the full cycle period, expressed in percent.
DCE: DC/DC Converter Enable
DCE_F: DC/DC Converter Enable Fault
DCF: DC/DC Converter Fault
DCL: Data Communication Link. A communication path between various in-vehicle electronic modules. Accessed by diagnostic tools through the data link connector (DLC).
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.
DRI: Deposit Resistant Injector. A fuel injector designed to prevent the build-up of carbon and other unwanted deposits.
DRIVECT: Number of completed OBD Drive Cycles PID
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.
ECT: Engine Coolant Temperature. Displayed in either Fahrenheit or Celsius.
ECTV: Electronically Controlled Continuously Variable Transaxle
EEC: Electronic Engine Control
EEC-V: Fifth-generation EEC system
EEPROM: Electrically Erasable Programmable Read Only Memory
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
EGRMC_F (1-4): Electric Exhaust Gas Recirculation Motor Control Fault
EGRMDSD: Electric Exhaust Gas Recirculation Motor Desired Position. The PID name used to operate the EEGR valve with diagnostic tools output state control.
EGRT: Exhaust Gas Recirculation Valve Temperature. A temperature sensor that is threaded into the bottom of the intake plenum.
EI: Integrated Electronic Ignition. An electronic ignition system that has the ignition control module (ICM) integrated into the PCM.
EI-LDR: Electronic Ignition-Low Data Rate
ENG CTO: Vehicle speed TCM received PID
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
ETC: Electronic Throttle Control
ETCVREF: Voltage Reference (5V) for ETC (APP BVREF, TP BVREF)
EVAP: Evaporative Emissions. A system to prevent fuel vapor from escaping into the atmosphere.
EVAPCP: Evaporative Canister Purge Solenoid. Controls a solenoid which allows venting of the evaporative purge canister.
EVAPCPF: Evaporative Canister Purge Solenoid Fault. Identifies whether an electrical fault exists for the current commanded state.
EVAPCV: Evaporative Canister Vent Solenoid. Controls a solenoid which seals the EVAP system canister from atmospheric pressure during the EVAP OBD Monitor test.
EVAPCVF: Evaporative Canister Vent Solenoid Fault.
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.
EVAPVMA: Evaporative Vapor Management Valve Internal Circuit Monitor
EVO: Electronic Variable Orifice
EVMV: Electric Vapor Management Valve. Also known as the EVAP canister purge valve.
Exciter Ring: A toothed or notched iron or steel disk which is the moveable part of a speed sensor.
FAN: Fan Speed
FC, FC1, FC2, FC3: Fan Control
FCS: Fuel Control Solenoid
FCIL: Fuel Cap Indicator Lamp. Indicates the fuel filler cap is not properly installed.
FEAD: Front End Accessory Drive
FEPS: Flash EEPROM Programming Signal. 18-volt DC signal sent by the diagnostic tool to initiate PCM reprogramming.
FLI: Fuel Level Input. Used by the EVAP monitor to calculate 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
FRPT: Fuel Rail Pressure Temperature Sensor
FRP V: Fuel Rail Pressure Voltage. A voltage input to the PCM from the fuel rail pressure sensor.
FRT: Fuel Rail Temperature
FRT_V: Fuel Rail Temperature Voltage
FRTMPAB: Engine Fuel Temperature-Bank 1 Input
FSC: Fail-Safe Cooling
FTIV: Fuel Tank Isolation Valve
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 time of last data update.
FUELPW1: Fuel Injector Pulse Width Number 1. Corresponds to injectors normally affected by HO2S11.
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
GCLTEMP: Generator Motor Coil Temperature
GCU: Generator Control Unit
GENMODE: Generator Motor operational mode TCM received PID
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.
GSDN: Generator Motor Shutdown
G_SDN: Generator Motor Shutdown Request PCM PID
G_SDN_A, G_SDN_C: Generator Motor Shutdown Request TCM PIDs
G_SPEED: Generator Motor Speed
GTQ_CMD: Measured generator motor torque PID
GTQ_OUT: Desired generator motor torque TCM received PID
G_INV_V: Actual generator motor inverter voltage
G_PHTEMP: Highest of 3 phases generator motor inverter temperature
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.
HFPIP: PIP up edge to PIP down edge time
HLOS: Hardware Limited Operating Strategy. A mode of operation where the PCM replaces output commands with fixed values in response to internal PCM malfunctions.
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.
HPUMP: Heater Pump Control
HPUMP_F: Heater Pump Fault
HS-CAN: High Speed Controller Area Network
HTR, HTR11, HTR12: HO2S Heater. Heater element for the HO2S sensor.
HTR11F, HTR12F: HO2S Heater Fault
HV_AMP: Traction battery current TCM received through the communication network PID.
HVBAT_V: Traction battery voltage TCM received through the communication network PID.
HVIL: High Voltage Interlock Circuit
HVINTLCK: High Voltage Interlock Circuit Status PID
HVIN: High Voltage Interlock Negative Circuit
HVIP: High Voltage Interlock Positive Circuit
HVN: High Voltage Negative Circuit
HVP: High Voltage Positive Circuit
Hydrogen: Chemical symbol H. Highly flammable gas.
Hz: Hertz. Cycles per second
IAT: Intake Air Temperature
IAT_V: Intake Air Temperature Voltage. Actual voltage drop across the IAT sensor.
IC: Integrated Circuit. A small semi-conductor device capable of doing many separate circuit functions.
IFS: Inertia Fuel Shut Off
IGN GND: Ignition Ground
Ignition: System used to provide high voltage spark for engines
IGN_KEY: Ignition Key
IGN_OFF: Ignition Switch Position OFF Input PID
IGN_R: Ignition Switch Position RUN Input PID
IGN_R/S: Ignition Switch Position START Input PID
IGN_SW: Ignition Switch Position
IMAP: Inferred MAP
IMRC: Intake Manifold Runner Control. Controls or modifies airflow through the engine air intake system.
IMRCM: Intake Manifold Runner Control Monitor. Monitors the IMRC circuits for faults.
INJ1, INJ2, INJ3, INJ4: Injector number or its signal output from the PCM.
INJ_TIM: Injector Timing Before Top Dead Center
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.
IPC: Independent Plausibility Checker
ISDN1, ISDN2: Immediate Shutdown Circuits 1 and 2
I_SDN_1, I_SDN_2: Immediate Shutdown 1 and 2 PIDs
ISP-R: Ignition Switch Position RUN Circuit
ISP-R/S: Ignition Switch Position START Circuit
ISO: International Standards Organization
ITCC: Intelligent Torque Controlled Coupling
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 key 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: Kilopascal. Unit of pressure. 3.386 kPa equals 1 inch of mercury (Hg.)
KS1: Knock Sensor Bank 1. Detects engine knock.
L: Liters. The unit of volume in the metric measuring system. One liter equals 1.06 quarts.
LDR: Low Data Rate. Type of misfire monitor.
LFC: Low Fan Control
LFCF: Low Fan Control Fault
LOAD: Calculated Engine Load
LONGFT1: Long-Term Fuel Trim Bank 1. Fuel flow adjustment determined by the PCM.
LOOP: Indicates OPEN or CLOSED loop status.
LOS: Limited Operating Strategy
LOSSTRT: Limited Operating Strategy related to the engine no start condition
LOS_BRK: Limited Operating Strategy related to regenerative braking fault
LOS_ENG: Limited Operating Strategy related to the engine fault
LOS_ETC: Limited Operating Strategy related to the ETC system fault
LOS_EQ: Limited Operating Strategy related to the E-Quizzer detected fault
LOS_GEN: Limited Operating Strategy related to the generator motor fault
LOS_HV: Limited Operating Strategy related to the high voltage traction battery fault
LOS_IPC: Limited Operating Strategy related to the independent plausibility checker detected fault
LOS_KEY: Limited Operating Strategy related to the ignition key position fault
LOS_LV: Limited Operating Strategy related to the low voltage system fault
LOS_MOT: Limited Operating Strategy related to the traction motor fault
LOS_OWC: Limited Operating Strategy related to the one way clutch fault
LOS_TCM: Limited Operating Strategy related to the transaxle fault
LPLR: Low Pressure Low Resistance fuel injector
MAF: Mass Air Flow
MAF_V: Mass Air Flow Voltage
MAF RTN: Mass Air Flow Return. A return circuit for the MAF sensor.
MAP: Manifold Absolute Pressure. The internal pressure of the intake manifold.
MAP_V: Manifold Absolute Pressure Voltage
MCLTEMP: Traction Motor Coil Temperature
MCU: Motor Control Unit
MECT: Motor Electronics Cooling Temperature
MECT_V: Motor Electronics Cooling Temperature Voltage
MECP: Motor Electronics Cooling Pump Control
MECP_F: Motor Electronics Cooling Pump Fault
MECP_V: Motor Electronics Cooling Pump Voltage
MFC: Medium Fan Control
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.
MSDN: Motor Shutdown
M_SDN: Motor Shutdown Request PCM PID
M_SDN_A, M_SDN_C: Traction motor shutdown request TCM PIDs
MTQ_CMD: Measured traction motor torque PID
MTQ_OUT: Desired traction motor torque TCM received PID
M_INV_V: Actual traction motor inverter voltage
M_PHTEMP: Highest of 3 phases traction motor inverter temperature
M_SPEED: Traction Motor Speed
MY: Model Year
NC: Normally Closed
NGS: New Generation Self-Test Automatic Readout (STAR) tester.
NO: Normally Open
NO X : Oxides of Nitrogen. Formed at high combustion temperatures.
O2S, O2S11, O2S12: Oxygen Sensor. Provides information on rich or lean exhaust conditions to the PCM.
O2S11SV, O2S12SV: Oxygen Sensor Voltage Input Pids.
OASIS: On-line Automotive Service Information System
OBD, OBD-II: On-Board Diagnostics, On-Board Diagnostics Second Generation. A system that monitors PCM input and output control signals.
On-Demand Test: The KOEO and KOER tests of the PCM and KOEO test of the TCM 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.
Open Circuit: A circuit which does not provide a complete path for flow of current.
OL: Open Loop. An operating condition based on instructions not modified by PCM feedback.
OSC: Output State Control
OTM: Output Test Mode
OWC: One Way Clutch
Ozone: A blue gaseous form of oxygen (O3 ) formed naturally by electric discharge or exposure to ultraviolet radiation.
PCM: Powertrain Control Module
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 PCM memory which contains operating information.
PIP: Profile Ignition Pickup. Provides crankshaft position information for ignition synchronization.
PIP_CTR: PIP counter
PIPTIM: Last PIP time
Potentiometer: An adjustable resistance component commonly used as a sensor (example: TP sensor).
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: 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.
PRNDL: Gear Selector Position
PRNDL_T: Gear Selector position TCM received PID
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.
PSCM: Power Steering Control Module
PSR: Power Sustain Relay
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.
PZEV: Partial Zero Emission Vehicle
Quick Test: A series of diagnostic tests consisting of KOEO, KOER, and continuous memory self-tests. The resulting DTCs are retrieved using the diagnostic tool.
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.
Relay: An electromechanical device in which connections in 1 circuit are opened or closed by changes in another circuit.
Repetitive Spark: Multiple firings of individual spark plugs at engine speeds below 1,000 RPM to improve idle quality and improve emissions.
RF: Radio Frequency
RFI: Radio Frequency Interference
RFS: Returnless Fuel System
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
RPMDSD: Desired engine speed
RTN: Return. A dedicated sensor ground circuit.
RWD: Rear Wheel Drive
SAE: Society of Automotive Engineers
SCCS: Speed Control Command Switch
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.
SHRTFT1: Short-Term Fuel Trim Bank 1. Fuel flow adjustment in response to the HO2S sensor input during closed-loop operation.
SIG RTN: Signal Return. A dedicated sensor ground circuit that is common to 2 or more sensors.
Smart Driver: A PCM or ECU output driver that can detect faults (open or shorts) on its output circuit.
SME: Society of Manufacturing Engineers
SOC: State Of Charge
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.
TACH: Tachometer
TACM: 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.
TBCM: Traction Battery Control Module
TCM: Transaxle Control Module
TCM_CAU: Caution indicator TCM commanded on.
TCM_HAZ: Hazard indicator TCM commanded on.
TDC: Top Dead Center
Tear Tag: The 2-piece adhesive label attached to the PCM to identify its calibration.
TFT: Transmission Fluid Temperature. Indicates the temperature of transmission fluid.
TGAC: Torque of Generator AC signal
Thermistor: A temperature dependent resistor 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.
TMAC: Torque of Motor AC signal
TORQUE: Engine torque TCM received PID
TQ_DSD: Desired Engine torque TCM received PID
TP: Throttle Position Sensor. A potentiometer that provides throttle angle and rate information for the PCM.
TP V: Throttle Position Sensor Voltage
TP_MODE: Throttle Position Mode
TP_V: Throttle Position Voltage Input
TPB: Secondary Throttle Position Voltage Input
TPREL: Lowest steady TP voltage since engine start
TR: Gear Position Indicated By Transmission Range Sensor
TR-A Sensor: Analog Transmission Range Sensor. Provides information to the PCM on the transmission range selector position.
TR_A1, TR_A2, TR_A3: TR-A 1, 2, and 3 inputs
Transducer: A device that receives energy from 1 medium and transfers it to another. For example, thermal energy is converted to an electrical signal through a temperature probe.
TRIPCNT: Number of completed OBD trips
TSB: Technical Service Bulletin. Notifies the technician of any known vehicle concerns, procedures, or general repair information.
Underspeed M ode: 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.
VBPWR: Vehicle Buffered Power. A PCM supplied power source that supplies regulated voltage.
VC: Vehicle Certification
VECI: Vehicle Emission Control Information label
VEHMODE: Vehicle operational mode TCM received PID
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. Controls the flow of fuel vapors out of the carbon canister.
VPWR: Vehicle Power. A switched circuit that provides power to the EEC system. Compare Battery Voltage (B+).
VREF: Reference Voltage. A dedicated circuit that provides approximately a 5 volt signal used as a reference by certain sensors.
VSC: Vehicle System Controller
VSS: Vehicle Speed Sensor. A magnetic pickup device that generates an AC signal that is proportional to the vehicle speed.
WAC: Wide Open Throttle A/C Cut-Off. Turns the A/C system off during wide open throttle or certain other operating conditions.
WOT: Wide Open Throttle. A condition of maximum airflow through the throttle body.
Zip Tube: Another name for fresh air duct or air inlet duct.