ASVAB Automotive Information 2 — Questions and Answers
Question 1: What is the purpose of a vehicle's PCV (Positive Crankcase Ventilation) valve?
- To control fuel pressure
- To vent blow-by gases from the crankcase back into the intake (Correct answer)
- To regulate engine coolant flow
- To adjust ignition timing
Correct answer: To vent blow-by gases from the crankcase back into the intake
The PCV valve routes harmful blow-by gases from the crankcase back into the intake manifold to be burned rather than released into the atmosphere.
Question 2: Which type of brake uses hydraulic pressure to squeeze brake pads against a rotor?
- Drum brake
- Disc brake (Correct answer)
- Band brake
- Shoe brake
Correct answer: Disc brake
Disc brakes use a hydraulic caliper to squeeze brake pads against a spinning rotor, creating friction to slow the vehicle.
Question 3: What does a vehicle's alternator do while the engine is running?
- Converts AC current to DC to start the engine
- Generates AC current converted to DC to charge the battery and power electronics (Correct answer)
- Regulates fuel injection timing
- Controls transmission shifting
Correct answer: Generates AC current converted to DC to charge the battery and power electronics
The alternator generates alternating current (AC) which is converted to direct current (DC) to recharge the battery and supply power to the vehicle's electrical systems.
Question 4: What is 'engine displacement'?
- The weight of the engine block
- The total volume swept by all pistons in one complete revolution (Correct answer)
- The distance the crankshaft travels
- The fuel capacity of the engine
Correct answer: The total volume swept by all pistons in one complete revolution
Engine displacement is the total volume swept by all pistons during one complete cycle, typically measured in liters or cubic inches.
Question 5: Which component in an automatic transmission uses fluid coupling to transmit power from the engine?
- Clutch pack
- Torque converter (Correct answer)
- Planetary gearset
- Valve body
Correct answer: Torque converter
The torque converter uses fluid coupling to transmit engine power to the transmission, allowing the vehicle to stop without stalling the engine.
Question 6: What is the function of the vehicle's EGR (Exhaust Gas Recirculation) system?
- To improve exhaust sound
- To recirculate a portion of exhaust gases back into the intake to reduce NOx emissions (Correct answer)
- To increase exhaust flow for better performance
- To filter particulates from exhaust
Correct answer: To recirculate a portion of exhaust gases back into the intake to reduce NOx emissions
The EGR system recirculates a portion of exhaust gases back into the combustion chamber to lower peak combustion temperatures and reduce nitrogen oxide (NOx) emissions.
Question 7: When a car's wheel is out of balance, what is the most common symptom?
- Engine misfire at idle
- Vibration felt in the steering wheel or seat at highway speeds (Correct answer)
- Difficulty shifting gears
- Poor fuel economy at low speeds
Correct answer: Vibration felt in the steering wheel or seat at highway speeds
An unbalanced wheel creates vibration that is typically felt through the steering wheel or floorboard, especially at highway speeds.
ASVAB Automotive Information 2
What is the purpose of a vehicle's PCV (Positive Crankcase Ventilation) valve?