ITI Mechanic Auto Electrical & Electronics (AITT Theory) key terms

Specialized clothing or equipment worn to minimize exposure to hazards, such as gloves, safety glasses, and insulated tools, essential when working on electrical and high-voltage vehicle systems.

Hand tools with non-conductive handles and shafts, rated for specific voltages, used to prevent electric shock when working near live circuits or high-voltage components.

Procedures and precautions for working on systems exceeding 60V DC or 30V AC, including de-energizing, lockout/tagout, and using rated PPE to prevent electrocution.

An electronic measuring instrument that combines functions such as voltmeter, ammeter, and ohmmeter, displaying measurements digitally, used for diagnosing electrical faults.

A test instrument that graphically displays voltage signals over time, allowing technicians to analyze waveform shape, amplitude, and frequency in electrical and electronic circuits.

A device that connects to a vehicle's diagnostic link connector to read fault codes, view live data, and communicate with electronic control units for troubleshooting.

An alphanumeric code stored by an electronic control unit when it detects a fault, helping technicians identify the affected system or component.

A fundamental relationship stating that current through a conductor equals the voltage across it divided by its resistance, expressed as I = V/R.

The electrical potential difference between two points, measured in volts, representing the force that drives current through a circuit.

The flow of electric charge through a conductor, measured in amperes, indicating the rate at which charge passes a point.

The opposition to the flow of electric current in a material, measured in ohms, causing electrical energy to be converted to heat.

A circuit configuration where components are connected end-to-end, providing a single path for current, so the same current flows through all components.

A circuit configuration where components are connected across common points, providing multiple paths for current, so voltage is the same across each branch.

The reduction in voltage across a component or conductor due to resistance, often used to locate excessive resistance in a circuit.

A rechargeable battery using lead plates and sulfuric acid electrolyte, commonly used in vehicles to supply power for starting, lighting, and ignition.

The amount of electric charge a battery can deliver, typically measured in ampere-hours (Ah) or reserve capacity, indicating how long it can supply current.

The present level of charge in a battery relative to its full capacity, expressed as a percentage, important for battery management and EV range estimation.

The vehicle system that generates and regulates electrical power to recharge the battery and run electrical loads while the engine is running, typically using an alternator.

A belt-driven generator that converts mechanical energy from the engine into alternating current, which is rectified to direct current to charge the battery and power vehicle systems.

A device that controls the output voltage of the alternator to prevent overcharging the battery and damaging electrical components, typically integrated into the alternator.

An electric motor that engages the engine flywheel to crank the engine until it starts, drawing high current from the battery through a solenoid.

An electromagnetic switch that, in a starter circuit, engages the starter drive and closes high-current contacts to supply power to the starter motor.

An induction coil that transforms low battery voltage into the high voltage needed to create a spark at the spark plug for igniting the air-fuel mixture.

A device that fits into the engine cylinder and provides a gap for an electric spark to jump, igniting the compressed air-fuel mixture.

The vehicle system that generates and delivers high-voltage sparks to the engine cylinders at the correct time to ignite the fuel-air mixture.

A robust vehicle bus standard that allows microcontrollers and devices to communicate with each other without a host computer, widely used in automotive multiplexing.

A technique of transmitting multiple signals over a single communication channel or wire, reducing wiring complexity in vehicles by sharing data among electronic modules.

A microprocessor-based module that controls one or more electrical systems in a vehicle by reading sensor inputs and commanding actuators based on programmed logic.

A device that detects changes in physical conditions, such as temperature or position, and converts them into electrical signals for the ECU to interpret.

An electromechanical device, such as a motor or solenoid, that converts electrical signals from the ECU into physical movement or action.

A protective device containing a metal strip that melts and breaks the circuit when current exceeds a rated value, preventing damage from overcurrent.

An electromagnetic switch that uses a small current to control a larger current circuit, commonly used in automotive electrical systems for switching high-power loads.

A semiconductor device that allows current to flow in one direction only, used for rectification and protection in automotive electronic circuits.

A semiconductor device used to amplify or switch electronic signals and electrical power, fundamental in ECU output circuits and control modules.

An electrical device, typically a diode bridge, that converts alternating current (AC) to direct current (DC), essential in alternators for battery charging.

An electronic system that monitors and controls the charging and discharging of a battery pack, ensuring safety, balancing cells, and reporting state of charge in electric vehicles.

A system in electric and hybrid vehicles that recovers kinetic energy during braking, converting it into electrical energy to recharge the battery.