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ASE A6 practice questions

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Question 1General Electrical/Electronic System Diagnosis

While the engine is cranking, a technician connects a voltmeter between the battery negative post and the starter housing. Which measurement is being taken?

  1. Available battery voltage
  2. Starter current draw
  3. Ground-side voltage drop Correct answer.
  4. Charging system output

Explanation

A voltmeter placed across a conductor while current flows through it displays the voltage dropped by that conductor's resistance. The ground side of the cranking circuit includes the battery cable, engine block and starter housing, so the reading shows how much voltage is lost returning to the battery. Excessive loss here means cranking performance suffers even with a good battery.

Question 2General Electrical/Electronic System Diagnosis

A 12-volt circuit contains a single 3-ohm resistor. How much current flows through the circuit?

  1. 4 amps Correct answer.
  2. 0.25 amp
  3. 36 amps
  4. 9 amps

Explanation

Ohm's law states that current equals voltage divided by resistance, so 12 volts divided by 3 ohms equals 4 amps. Current rises as resistance falls for a fixed voltage.

Question 3General Electrical/Electronic System Diagnosis

Which component protects a circuit by melting open when current exceeds its rating?

  1. Relay
  2. Diode
  3. Resistor
  4. Fuse Correct answer.

Explanation

A fuse contains a calibrated strip or element that melts when current exceeds its rating, opening the circuit before wiring or components are damaged. It must be replaced after it operates.

Question 4General Electrical/Electronic System Diagnosis

A technician needs to measure current through a fuel pump circuit without opening the wiring. Which tool is appropriate?

  1. Inductive current clamp Correct answer.
  2. Test light
  3. Ohmmeter
  4. Voltmeter

Explanation

An inductive current clamp senses the magnetic field around a conductor and displays amperage without breaking the circuit. This is the preferred method for measuring current on sealed modern harnesses.

Question 5General Electrical/Electronic System Diagnosis

A battery has been sitting overnight with no load and reads 12.2 volts. What does this indicate?

  1. About 50 percent state of charge Correct answer.
  2. About 25 percent state of charge
  3. About 100 percent state of charge
  4. About 75 percent state of charge

Explanation

Open-circuit voltage tracks state of charge: roughly 12.6 volts is fully charged, 12.2 volts is about half charged, and 12.0 volts is close to 25 percent. The battery should be recharged and then load tested.

Question 6General Electrical/Electronic System Diagnosis

Which check confirms that a blade fuse is passing current in an energized circuit?

  1. Current through the fuse with the circuit off
  2. Resistance across the fuse with the circuit energized
  3. Resistance from each fuse terminal to ground
  4. Voltage on both fuse terminals with the circuit on Correct answer.

Explanation

With the circuit energized and current flowing, a good fuse shows nearly the same voltage on both terminals because its resistance is very low. A measurable difference between terminals means the fuse element is open or corroded.

Question 7General Electrical/Electronic System Diagnosis

A test light clipped to battery positive lights when its probe touches a circuit point. What does this indicate about that point?

  1. The point is shorted to battery positive
  2. The circuit has excessive resistance
  3. The point is open-circuited
  4. The point has a path to ground Correct answer.

Explanation

The lamp needs both a source of voltage and a path to ground to light. Since the clip supplies battery positive, the lamp lighting proves the probed point completes the circuit to ground.

Question 8General Electrical/Electronic System Diagnosis

Which component allows current to flow in one direction only?

  1. Capacitor
  2. Diode Correct answer.
  3. Relay
  4. Resistor

Explanation

A diode is a semiconductor junction that conducts when forward biased and blocks current when reverse biased. This property is used for rectification and for suppressing voltage spikes.

Question 9General Electrical/Electronic System Diagnosis

A late-model vehicle has a key-off battery drain. After all modules have gone to sleep, which measured draw is normal?

  1. 20 to 50 milliamps Correct answer.
  2. Roughly 400 to 500 milliamps
  3. About 5 amps
  4. About 2 amps

Explanation

After sleep, most manufacturers specify a total parasitic draw in the range of about 20 to 50 milliamps, though some allow up to roughly 80 milliamps. Draw above specification will discharge the battery over days.

Question 10General Electrical/Electronic System Diagnosis

Two 6-ohm resistors are connected in series across a 12-volt source. What is the total current?

  1. 4 amps
  2. 2 amps
  3. 0.5 amp
  4. 1 amp Correct answer.

Explanation

In series, resistances add, giving 12 ohms total. Dividing 12 volts by 12 ohms yields 1 amp, which is the same current through both resistors.

Question 11General Electrical/Electronic System Diagnosis

Two 12-ohm resistors are connected in parallel across a 12-volt source. What is the total current from the source?

  1. 0.5 amp
  2. 24 amps
  3. 1 amp
  4. 2 amps Correct answer.

Explanation

Each branch sees the full 12 volts, so each draws 1 amp. Total current in a parallel circuit is the sum of branch currents, giving 2 amps.

Question 12General Electrical/Electronic System Diagnosis

An ohmmeter reads infinite resistance across the coil terminals of a relay removed from the vehicle. What is the most likely result when the relay is installed?

  1. The relay chatters rapidly
  2. The contacts stay welded closed
  3. The relay clicks but has no output
  4. The relay will not energize Correct answer.

Explanation

An open coil cannot create the magnetic field that pulls the contacts closed, so the relay cannot energize at all. Infinite coil resistance indicates a broken winding.

Question 13General Electrical/Electronic System Diagnosis

With the engine running, battery voltage is 13.2 volts against a specification of 13.8 to 14.8 volts, and AC ripple measures 0.9 volt AC against a limit of 0.5 volt. What is the most likely cause?

  1. A weak battery
  2. Worn alternator brushes
  3. Failed rectifier diodes Correct answer.
  4. A slipping alternator belt

Explanation

High AC ripple with low charging voltage shows that one or more rectifier diodes are not conducting, leaving part of the AC waveform unfiltered. Belt slip normally shows as noise or low output without elevated ripple.

Question 14General Electrical/Electronic System Diagnosis

A cranking current test shows 180 amps on a starter with a specification of 150 to 200 amps, and cranking speed is normal. What does this indicate?

  1. Within specification Correct answer.
  2. A starter drawing too much current
  3. Excessive circuit resistance
  4. A discharged battery

Explanation

Current draw inside the specified range with normal cranking speed shows the starter and its cables are working as designed. Current draw is compared against both the amperage specification and cranking rpm.

Question 15General Electrical/Electronic System Diagnosis

A headlamp is dim, and with the lamp on a voltmeter reads 2.5 volts between the lamp ground terminal and battery negative. What does this indicate?

  1. An overcharging charging system
  2. High resistance in the ground path Correct answer.
  3. Normal operation of the headlamp circuit
  4. A completely open ground circuit

Explanation

Voltage appearing across the ground side while current flows means the ground path is dropping voltage that should reach the lamp. A good ground path typically drops less than about 0.1 volt under load.

Question 16General Electrical/Electronic System Diagnosis

What condition must exist before a DVOM can accurately measure resistance?

  1. Circuit off and isolated Correct answer.
  2. A load connected in the circuit
  3. The engine running at 2000 rpm
  4. The circuit energized and loaded

Explanation

An ohmmeter supplies its own small reference current, so any external voltage or parallel path corrupts the reading and may damage the meter. The component must be de-energized and disconnected from parallel paths.

Question 17General Electrical/Electronic System Diagnosis

A circuit blows its fuse immediately every time it is energized. Which condition is the most likely cause?

  1. High resistance at a connector
  2. A short to ground Correct answer.
  3. A loose ground strap
  4. An open in the load device

Explanation

A direct short to ground bypasses the load and allows near-unlimited current, which opens the fuse almost instantly. Opens and high resistance reduce current, so they do not blow fuses.

Question 18General Electrical/Electronic System Diagnosis

An NTC coolant temperature sensor is measured and found to have unusually high resistance. How will the control module interpret this signal?

  1. Low coolant temperature Correct answer.
  2. An open sensor circuit
  3. A shorted sensor signal
  4. High coolant temperature

Explanation

In a negative temperature coefficient sensor, resistance falls as temperature rises, so high resistance corresponds to a cold engine. The module uses this value for fuel enrichment and fan strategy.

Question 19General Electrical/Electronic System Diagnosis

What is the purpose of a diode connected across a relay coil?

  1. Suppress the coil's voltage spike Correct answer.
  2. Speed up contact closing
  3. Reduce arcing across the contacts
  4. Increase coil current

Explanation

When the coil circuit opens, the collapsing magnetic field generates a high reverse voltage. The diode provides a path that clamps this spike and protects the control module driving the coil.

Question 20General Electrical/Electronic System Diagnosis

A vehicle uses a two-wire bus with a 120-ohm terminating resistor at each end. What resistance should be measured between the two data lines with the bus powered down?

  1. 240 ohms
  2. 30 ohms
  3. 120 ohms
  4. 60 ohms Correct answer.

Explanation

The two terminators are in parallel across the bus when all modules are disconnected or asleep, so 120 ohms in parallel with 120 ohms equals 60 ohms. A reading of 120 ohms indicates one terminator is missing or open.

Question 21General Electrical/Electronic System Diagnosis

A starter cranks slowly. The battery passes a load test, cranking current is normal, voltage drop across the positive cable is 0.9 volt, and voltage drop on the ground side is 0.1 volt. What is the next step?

  1. Replace the ground cable
  2. Replace the battery
  3. Replace the starter motor assembly
  4. Service the positive cable Correct answer.

Explanation

Voltage drop above roughly 0.5 volt on a cranking cable is excessive and robs the starter of voltage. The positive cable and its connections are the only part of the circuit failing the test, so they should be repaired before condemning the starter.

Question 22General Electrical/Electronic System Diagnosis

A starter draws 300 amps against a specification of 150 to 200 amps and cranks slowly. The battery passes a load test and both battery cables pass a voltage drop test. What is the most likely cause?

  1. An open hold-in winding
  2. High resistance in the ground cable
  3. Excessive internal starter drag Correct answer.
  4. Normal starter operation

Explanation

With supply cables and battery proven good, abnormally high current with slow cranking points to excessive mechanical drag or a shorted starter internally. The high current is the starter's response to being hard to turn or having low internal resistance.

Question 23General Electrical/Electronic System Diagnosis

A vehicle has an 850-milliamp key-off draw. Disconnecting the alternator output cable drops the draw to 30 milliamps. What is the most likely cause?

  1. A stuck cooling fan relay
  2. A faulty body control module
  3. A lamp left on in the glove box
  4. Leaking alternator rectifier diodes Correct answer.

Explanation

Removing the alternator from the circuit eliminated the excess draw, which identifies the alternator as the source. A failed rectifier diode can leak current to ground even with the engine off.

Question 24General Electrical/Electronic System Diagnosis

A throttle position sensor passes a static voltage check at closed and wide-open throttle, but the vehicle has a intermittent stumble. What is the best next test?

  1. Check reference voltage with the key on
  2. Measure TPS resistance at closed throttle only
  3. Graph the signal during a slow throttle sweep Correct answer.
  4. Compare TPS voltage to MAP voltage

Explanation

Intermittent signal dropouts often occur at a worn spot on the potentiometer track and are invisible to two-point static checks. Graphing the signal through the full sweep reveals momentary glitches or non-linear steps.

Question 25General Electrical/Electronic System Diagnosis

Two loads are wired in series and one of them has failed open. With the circuit energized, what voltage will be measured across the open component?

  1. Battery voltage Correct answer.
  2. One-third of battery voltage
  3. Zero volts
  4. Half of battery voltage

Explanation

No current can flow in an open series circuit, so there is no voltage drop across the intact component. The full source voltage therefore appears across the open, which is why a voltmeter can locate an open in a series string.

Question 26General Electrical/Electronic System Diagnosis

On an automotive wiring diagram, a solid dot shown at the point where two circuit lines cross indicates that the two wires are:

  1. Crossing without any electrical connection
  2. Twisted together but insulated from one another
  3. Electrically joined at that point Correct answer.
  4. Connected to chassis ground at that point

Explanation

Wiring diagrams use a solid dot (node) to show that crossing lines are spliced or joined, so current can pass between them. Lines that cross with no dot are simply routed past each other and are not connected. This convention lets a technician trace shared power feeds and splices correctly.

Question 27General Electrical/Electronic System Diagnosis

A solenoid is driven by a pulse-width-modulated driver operating at a 40% duty cycle. The supply voltage is 12.5 volts. What average voltage is applied to the solenoid?

  1. 5.0 volts Correct answer.
  2. 0.4 volt
  3. 7.5 volts
  4. 12.5 volts

Explanation

In pulse-width modulation, the average voltage equals the duty cycle multiplied by the supply voltage. Here 0.40 times 12.5 volts equals 5.0 volts. The driver switches the full supply on and off rapidly, so the solenoid responds to the average.

Question 28General Electrical/Electronic System Diagnosis

A power window on one door does not move. With the switch held in the UP position and a voltmeter backprobing the two motor wires at the motor connector, both wires read battery voltage. The motor runs normally when battery voltage and ground are jumped directly to it. What is the most likely cause?

  1. The window regulator is binding in its tracks.
  2. The motor armature winding is open internally.
  3. The ground path for the motor circuit is open. Correct answer.
  4. The window switch is not passing battery voltage to the motor.

Explanation

In a two-wire reversible motor circuit, the switch applies power to one wire and ground to the other. If both wires read battery voltage, power is reaching the motor but the ground side is not completing the circuit, so the second wire is pulled up through the motor winding. The intact motor and the correct voltage reading rule out a power feed or motor fault.

Question 29General Electrical/Electronic System Diagnosis

A fully charged 12-volt lead-acid battery that has been resting and has no surface charge should show an open-circuit voltage closest to:

  1. 12.6 V Correct answer.
  2. 12.2 V
  3. 13.8 V
  4. 11.8 V

Explanation

A healthy, fully charged lead-acid battery at room temperature has an open-circuit voltage of about 12.6 V. Each cell produces roughly 2.1 V, and six cells in series give that value. Readings are taken after surface charge is removed and the battery has rested.

Question 30General Electrical/Electronic System Diagnosis

A hydrometer reading of 1.265 on a flooded battery at 80°F indicates:

  1. A discharged battery
  2. An overcharged battery
  3. A battery at about half charge
  4. A fully charged battery Correct answer.

Explanation

Specific gravity of about 1.265 at 80°F corresponds to a fully charged flooded lead-acid battery. Hydrometer readings must be temperature-corrected; readings fall as state of charge drops.

Question 31General Electrical/Electronic System Diagnosis

White powdery corrosion around a battery terminal is best cleaned with:

  1. A commercial glass cleaner
  2. Clean water under low pressure
  3. A petroleum-based parts solvent
  4. Baking soda mixed with water Correct answer.

Explanation

The white deposit is lead sulfate from acid vapors and is acidic, so a baking soda and water paste neutralizes it. After cleaning, the terminal and clamp should be rinsed and dried before reassembly.

Question 32General Electrical/Electronic System Diagnosis

When jump-starting a vehicle with a dead battery, the final connection should be made to:

  1. An engine ground on the dead vehicle Correct answer.
  2. The negative terminal of the good battery
  3. The positive terminal of the good battery
  4. The negative terminal of the dead battery

Explanation

The final jumper connection is made to a solid engine ground away from the dead battery so any spark occurs away from hydrogen gas. The positive-to-positive and good-negative connections are made first.

Question 33General Electrical/Electronic System Diagnosis

A battery that is not secured by its hold-down can be damaged because:

  1. Vibration can crack plates and the case Correct answer.
  2. It will overcharge the charging system
  3. It will reverse its polarity
  4. It will lose electrolyte through the vent caps

Explanation

The hold-down prevents vibration and movement that can crack plates, damage internal connections, and wear the case. A loose battery also stresses its cables and terminals.

Question 34General Electrical/Electronic System Diagnosis

Before checking open-circuit voltage on a battery that was just charged, you should:

  1. Add electrolyte to each cell
  2. Read the voltage immediately after charging
  3. Tilt the battery to mix the electrolyte
  4. Load the battery briefly to remove surface charge Correct answer.

Explanation

Charging leaves a surface charge that makes open-circuit voltage read artificially high. Applying a brief load, such as headlights for about 15 seconds, removes it so the true state of charge can be read.

Question 35General Electrical/Electronic System Diagnosis

During a battery load test at 70°F, the battery voltage should remain above what value for 15 seconds with a load of half the rated CCA?

  1. 9.6 V Correct answer.
  2. 8.5 V
  3. 12.0 V
  4. 10.5 V

Explanation

A conventional load test applies half the rated cold cranking amps for 15 seconds. At 70°F the battery should stay above 9.6 V; lower voltage indicates a weak or discharged battery.

Question 36General Electrical/Electronic System Diagnosis

When measuring parasitic draw with a digital ammeter, the meter should be connected:

  1. From the positive post to the engine block
  2. In series with the negative battery cable Correct answer.
  3. Across the battery terminals
  4. In parallel with the main fuse

Explanation

Parasitic draw is current flowing out of the battery with the key off, so the ammeter must be placed in series in the negative cable path. The meter's fuse rating must exceed the expected current, and modules should be allowed to sleep.

Question 37General Electrical/Electronic System Diagnosis

A conductance tester evaluates a battery by:

  1. Checking electrolyte specific gravity with a hydrometer
  2. Measuring charging system ripple voltage
  3. Estimating current capacity from internal resistance Correct answer.
  4. Applying a carbon pile load for fifteen seconds

Explanation

A conductance tester applies a small AC signal and calculates internal resistance, then estimates available cranking current. It does not discharge the battery like a carbon pile load test.

Question 38General Electrical/Electronic System Diagnosis

A common recommended slow-charge rate for an automotive battery is approximately:

  1. Ten percent of the battery's ampere-hour rating Correct answer.
  2. The same as its cold cranking amp rating
  3. Fifty amps
  4. Two amps regardless of battery size

Explanation

A slow charge is generally about 10 percent of the battery's ampere-hour capacity, which limits heating and gassing. Higher rates may be used by some chargers but require closer monitoring.

Question 39General Electrical/Electronic System Diagnosis

Compared with a flooded battery of the same size, an AGM battery generally requires:

  1. Higher charging voltage with more venting
  2. A lower maximum charging voltage Correct answer.
  3. Monthly equalization charging
  4. Periodic addition of distilled water

Explanation

AGM batteries are valve-regulated and are sensitive to overvoltage, which can dry out the glass mat and damage the battery. Charging voltage must be limited to the manufacturer's AGM specification.

Question 40General Electrical/Electronic System Diagnosis

On some vehicles with smart charging systems, battery registration after replacement is necessary because:

  1. The charging system must relearn battery age and capacity Correct answer.
  2. It calibrates the fuel gauge sender
  3. It unlocks the immobilizer after a battery swap
  4. It resets all radio station presets and the clock

Explanation

Smart charging systems adjust charging strategy based on battery age, capacity, and type. Registration tells the control module that a new battery is installed so it does not overcharge or undercharge it.

Question 41General Electrical/Electronic System Diagnosis

A memory saver is used when disconnecting a vehicle battery to:

  1. Maintain power to electronic modules and presets Correct answer.
  2. Increase available cranking current during the swap
  3. Discharge the capacitors before service
  4. Prevent the battery from freezing in cold weather

Explanation

A memory saver supplies a small current through the data link connector or a power port to keep module memory and presets alive while the battery is disconnected. It does not power the starter or major loads.

Question 42General Electrical/Electronic System Diagnosis

While cranking, a voltage drop of 0.7 V is measured across the negative battery cable from the post to the engine block. This indicates:

  1. Excessive resistance in the cable or connections Correct answer.
  2. A discharged battery with low voltage
  3. Normal operation for a cranking circuit
  4. An open starter solenoid winding

Explanation

Voltage drop testing measures resistance in the path; a good cable and connections typically drop less than about 0.2 to 0.3 V during cranking. A 0.7 V drop indicates corrosion, a loose connection, or a damaged cable.

Question 43General Electrical/Electronic System Diagnosis

After all modules have gone to sleep, a typical acceptable parasitic draw on a modern vehicle is:

  1. 20 to 50 mA Correct answer.
  2. 2 to 3 A
  3. 150 to 200 mA
  4. 500 to 700 mA

Explanation

Modern vehicles commonly draw about 20 to 50 mA after modules sleep. Higher draw may be normal temporarily after shutdown, so the system must be allowed to time out before testing.

Question 44General Electrical/Electronic System Diagnosis

A battery left discharged for several months develops hard lead sulfate on its plates. The result is:

  1. Lost capacity that charging cannot restore Correct answer.
  2. Increased reserve capacity after charging
  3. Lower charging voltage requirements
  4. Higher specific gravity readings

Explanation

Hard sulfation forms when a battery sits discharged, and the crystals no longer readily convert back during charging. This reduces active plate area and permanently lowers capacity.

Question 45General Electrical/Electronic System Diagnosis

As battery temperature drops, its available cranking current:

  1. Remains unchanged until the battery freezes
  2. Increases because internal resistance falls
  3. Increases because the electrolyte thickens
  4. Decreases because the chemical reaction slows Correct answer.

Explanation

Cold temperature slows the chemical reaction and increases electrolyte viscosity, so the battery can deliver less current. CCA ratings are defined at 0°F to account for this effect.

Question 46General Electrical/Electronic System Diagnosis

When replacing a battery, the most important ratings to match are:

  1. Case color and label appearance
  2. Group size, CCA, and reserve capacity Correct answer.
  3. Reserve capacity only
  4. Cold cranking amps only

Explanation

The replacement must physically fit the tray and hold-down, provide enough cold cranking amps for starting, and meet reserve capacity for electrical loads. Matching only one rating can leave the vehicle underpowered or improperly secured.

Question 47General Electrical/Electronic System Diagnosis

When removing a battery from a vehicle, the safe sequence is to disconnect:

  1. The positive cable first
  2. Both cables at the same time
  3. The charger first
  4. The negative cable first Correct answer.

Explanation

Disconnecting the negative cable first reduces the chance of a wrench touching grounded metal and causing a short through the positive terminal. When installing, connect the positive first and negative last.

Question 48General Electrical/Electronic System Diagnosis

A parasitic draw is suspected but the battery current is normal. To locate the circuit, you can:

  1. Run the engine and watch charging voltage
  2. Disconnect the alternator and retest
  3. Measure millivolt drop across the fuses Correct answer.
  4. Measure AC voltage across the battery

Explanation

Current flowing through a fuse produces a small voltage drop proportional to current. Measuring millivolts across fuses with a high-resolution meter can identify the circuit carrying the draw without pulling fuses.

Question 49General Electrical/Electronic System Diagnosis

A conductance tester shows a battery is good, but the battery fails to crank the engine. A likely explanation is:

  1. The alternator is overcharging the battery
  2. The tester always overstates the CCA rating
  3. The starter is grounded to the frame
  4. Low state of charge or a bad cell Correct answer.

Explanation

Conductance testers estimate capacity and are most reliable on a fully charged battery; a deeply discharged battery or a cell problem can mislead the result. The battery should be charged and retested, and cranking voltage drop should be checked.

Question 50General Electrical/Electronic System Diagnosis

An intermittent parasitic draw is best diagnosed by:

  1. Performing a hydrometer test on each cell
  2. Checking charging voltage at idle speed
  3. Testing with a carbon pile load tester
  4. Monitoring current with an ammeter over time Correct answer.

Explanation

Intermittent draw may appear only after a module wakes or a timer operates, so current must be monitored while the vehicle sits. A recording ammeter or current clamp can capture the event.