ASE Practice Test #2 2 Flashcards

A vehicle's power steering is hard to turn at low speeds but normal at highway speeds. What component is MOST likely responsible?

Answer: A faulty or worn power steering pump not developing adequate pressure at low RPM, or a failing flow control valve

Hydraulic power steering assistance is generated by the pump. At low engine RPM (idle, parking maneuvers), if the pump is worn or the flow control valve is malfunctioning, adequate pressure may not be generated, making steering heavy. At higher engine RPM (highway), the pump turns faster and generates more flow and pressure, providing normal assistance. Testing power steering pump pressure and flow at idle confirms this diagnosis. A worn pump will show low pressure at idle but may be adequate at higher RPM.

During a transmission fluid level check on an automatic transmission with a dipstick, the technician finds the fluid level is correct but the fluid is dark brown and has a burnt smell. What is recommended?

Answer: Change the transmission fluid and filter — dark, burnt fluid indicates thermal degradation and potential internal clutch pack damage that requires immediate service and further diagnosis

Automatic transmission fluid (ATF) should be translucent red. Dark brown or black coloring indicates the fluid has been severely overheated, causing the friction modifier additives to degrade and clutch material to contaminate the fluid. A burnt smell confirms overheating. Immediate fluid and filter change removes contaminated fluid. If internal clutch damage has already occurred (slipping, delayed engagement), further diagnosis of internal components is required. Adding fluid or flush additives does not restore degraded ATF properties.

What is the purpose of the mass airflow (MAF) sensor in a fuel-injected engine?

Answer: To directly measure the mass of air entering the engine, providing the primary data for the ECM to calculate the correct fuel injection pulse width

The MAF sensor (typically a hot-wire or hot-film type) measures the actual mass (not just volume) of air entering the engine. Air mass is the critical input for calculating fuel quantity — since fuel must be metered proportional to air mass for the correct stoichiometric ratio regardless of altitude, temperature, and humidity (which affect air density). The ECM uses MAF data as the primary input for injector pulse width calculation in a mass airflow-based fuel control strategy.

A front-wheel drive vehicle vibrates during acceleration but not at a steady cruise speed. What is the MOST likely cause?

Answer: A worn or damaged constant velocity (CV) joint on a front axle shaft — worn CV joints typically vibrate under torque load during acceleration but can be smooth at constant load

CV joints on front-wheel drive axle shafts allow the front wheels to both drive and steer. As CV joints wear, their balls and races develop play and roughness. This is most noticeable during acceleration (when maximum torque passes through the joint) or when turning while accelerating. A clicking sound when turning at low speed is typical of an outer CV joint. Vibration under acceleration (without a click) is more typical of an inner CV joint issue. Smooth cruise means the joint is still functional but failing.

What does the term "cold crank amperage" (CCA) rating indicate on a battery?

Answer: The amperage the battery can deliver for 30 seconds at 0°F (-18°C) while maintaining at least 7.2V — higher CCA means better cold-weather starting ability

CCA (Cold Cranking Amps) is the standardized battery performance rating for cold-weather starting. It specifies the current the battery can sustain for 30 seconds at 0°F while keeping voltage above 7.2V (the minimum needed to reliably crank a starter). Cold temperatures significantly reduce battery electrochemical activity, reducing available power. A battery must meet or exceed the vehicle manufacturer's minimum CCA requirement for reliable cold starting. Lower CCA batteries struggle in cold climates.

When diagnosing a "click-no-crank" condition, a technician hears one solid click when the key is turned to start. What does this indicate?

Answer: The starter solenoid is engaging (the single click) but the starter motor is not turning — likely a failed starter motor, seized engine, or high resistance in the starter circuit

A single loud click when the key is turned to start indicates the starter solenoid has activated (its engagement click). The solenoid connects battery power to the starter motor. If the motor does not turn after solenoid engagement, the motor itself has failed (open armature winding, seized bearings), the engine is seized, or there is excessive resistance in the battery-to-starter power circuit. Repeated clicking (rapid clicking) indicates low battery voltage, not a starter failure.