ASE Automobile (A1–A8) — All Questions

In American Wire Gauge (AWG), a wire with a smaller gauge number:

• a.has more resistance per foot
• b.is physically larger and carries more current✓
• c.is smaller in diameter and carries less current
• d.is suitable only for ground connections and nothing else

In AWG, the numbering is inverse: a smaller number means a larger-diameter conductor with lower resistance and higher current capacity. Choosing adequate wire size for the load and length prevents voltage drop and overheating. Battery cables use very low gauge numbers.

The preferred method for a reliable, permanent automotive wire repair is generally to:

• a.solder or use a proper crimp connector, then seal the joint✓
• b.twist the bare wires together and wrap them with electrical tape only
• c.splice by pressing metal staples through the wire's insulation
• d.join the connection together using a common household wire nut

A soldered or properly crimped connection sealed with adhesive-lined heat shrink resists corrosion and vibration for a durable repair. Twisting and taping or using wire nuts is unreliable in a vehicle's environment. Manufacturer procedures may specify crimp-and-seal for certain circuits.

On a standard ISO relay, terminals 85 and 86 connect to the:

• a.control coil that creates the magnetic field✓
• b.chassis ground bus that the relay case connects to
• c.heavy high-current load contacts inside the relay body
• d.battery positive feed terminal on the relay only

Terminals 85 and 86 energize the relay's coil, while 30 and 87 (and 87a) carry the switched high-current load. Energizing the coil moves the contacts to power the load. Knowing this layout lets a technician bench-test or bypass a relay safely.

A fuel-gauge sending unit in the tank typically signals fuel level to the gauge using a float connected to a:

• a.thermistor that senses the temperature of the fuel in the tank
• b.small internal alternator that generates voltage with the level
• c.pressure switch that simply opens when the tank runs empty
• d.variable resistor (rheostat) whose resistance changes with level✓

The float moves a wiper along a resistor, changing resistance as the level rises or falls, and the gauge or module reads that as fuel level. A worn resistor card can cause erratic or stuck readings. Modern systems may process the signal through a module.

An oil-pressure warning lamp is usually operated by a switch that:

• a.opens the charging circuit whenever the oil pressure drops
• b.produces its own signal voltage internally from the engine oil pump
• c.measures the engine coolant temperature rather than oil pressure
• d.closes to ground and lights the lamp when oil pressure is low✓

A simple oil-pressure warning switch grounds the lamp circuit when pressure is below its threshold, turning the light on. Rising oil pressure opens the switch and the lamp goes out. A gauge-type sender instead varies resistance to move a pointer.

A door-operated dome (courtesy) light most commonly turns on when the door switch:

• a.increases the bulb's resistance
• b.provides a path to ground for the lamp circuit✓
• c.disconnects the courtesy lamp entirely from its fuse feed
• d.sends charging voltage from the alternator to the battery

Many courtesy lamps are always supplied with power and light when the door jamb switch completes the ground path as the door opens. A stuck or corroded switch can leave the light on and drain the battery. Body modules now often control this timing.

A blower motor that runs only on high speed but not on lower speeds most likely has a fault in the:

• a.alternator diode rectifier bridge
• b.blower motor resistor (or its control module)✓
• c.blower motor itself, which has failed completely
• d.battery, which cannot supply enough current for low speeds

Lower fan speeds pass current through a resistor pack (or solid-state control); high speed usually bypasses it, so if only high works, the resistor or its circuit is open. The motor itself is proven good because high speed operates. Corrosion at the resistor connector is a common cause.

Technician A says a digital multimeter's min/max feature can help catch an intermittent voltage glitch. Technician B says a graphing meter or scope shows signal changes over time better than a numeric display. Who is correct?

• a.Both A and B✓
• b.Technician B only
• c.Technician A only
• d.Neither A nor B

Min/max recording captures brief highs and lows a technician might miss while watching, and a graphing meter or oscilloscope displays the waveform to reveal dropouts and noise. Both technicians are correct. Choosing the right tool speeds intermittent-fault diagnosis.

Corroded or loose battery terminals commonly cause which symptom?

• a.a steady, abnormally high engine idle speed when warm
• b.overcharging of an otherwise healthy and fully charged battery
• c.excessive alternator output voltage at highway cruising speed
• d.slow or no cranking and intermittent electrical problems✓

Resistance at the terminals limits current to the starter and other loads, causing slow cranking, no-starts, or flickering electronics. Cleaning the posts and clamps and tightening them restores a solid connection. A voltage-drop test confirms terminal resistance.

On a hybrid or electric vehicle, cables and components colored bright orange indicate:

• a.low-voltage accessory wiring that is completely safe to touch
• b.the vehicle's chassis and body ground connection points
• c.high-voltage circuits that require special safety precautions✓
• d.standard 12-volt starter and main battery cables

Orange insulation and connectors mark the high-voltage system, which can be lethal; technicians must follow de-energizing procedures and use insulated tools and gloves. Never cut or probe orange cabling without proper training. Service information specifies the shutdown steps.

A relay is often used instead of running full load current through a dashboard switch because it:

• a.increases the total system voltage that is available to the load
• b.lets a small switch current control a much larger load current✓
• c.converts the vehicle's direct current into alternating current
• d.removes any need for a protective fuse in the load circuit

A relay uses a low-current control circuit to close heavy-duty contacts, so the dash switch and its wiring stay small and cool while the relay handles the high current. This protects switches and reduces voltage drop to the load. Headlights, fuel pumps, and fans commonly use relays.

A short to power (a wire touching a constant hot source) differs from a short to ground because a short to power will:

• a.stop all current flow in the vehicle
• b.cause a load to operate when it should be off✓
• c.always blow the circuit's protective fuse immediately
• d.occur only inside the alternator's rectifier bridge

A short to power feeds voltage into a circuit that should be off, so a lamp or motor may run unexpectedly, whereas a short to ground usually blows a fuse. Backprobing and isolating sections of the harness helps locate it. Wiring diagrams show where an accidental power feed could originate.

A wheel-related speed signal used by the speedometer and other systems is often produced by a:

• a.hydrometer that measures the movement of fluid in the axle
• b.sensor that generates a signal as a toothed ring passes it✓
• c.potentiometer that is turned directly by the steering wheel
• d.thermistor that changes its resistance as the vehicle speed changes

Vehicle and wheel speed sensors typically use a magnetic or Hall-effect pickup that produces pulses as a toothed reluctor or tone ring rotates. The module converts pulse frequency into speed. A damaged tone ring or sensor causes speed-signal faults and can affect ABS and the speedometer.

A test light is useful for quick checks but is less desirable than a digital multimeter for some tests because a test light:

• a.draws no current at all from the circuit that is being tested
• b.reads circuit resistance more accurately than a meter does
• c.is the required tool for measuring electrolyte specific gravity
• d.cannot measure exact voltage and may load sensitive circuits✓

A test light only shows presence of voltage and can draw enough current to damage low-power electronic circuits, while a DVOM gives precise measurements with very high input impedance. Use a high-impedance meter on computer and sensor circuits. The test light still has value for quick power/ground checks on robust circuits.

A component that stores an electrical charge and is often used to reduce voltage spikes or noise is a:

• a.thermistor
• b.relay coil
• c.capacitor✓
• d.diode

A capacitor stores charge and can smooth voltage or absorb spikes, such as suppressing radio noise or stabilizing a circuit. A diode, by contrast, allows current one way, and a thermistor changes resistance with temperature. Capacitors are common in filtering and timing applications.

If two 12-volt loads are wired in parallel across the battery, the total current drawn from the battery is:

• a.zero, because the two branch currents cancel out
• b.always less than the current drawn by either load alone
• c.the sum of the currents drawn by each load✓
• d.the same as one load by itself

Because parallel branches each draw their own current at full source voltage, the battery must supply the sum of both branch currents. Adding parallel loads therefore increases total draw and can overload a shared fuse. This is why circuit and fuse capacity must match the combined load.

A gauge that reads inaccurately high or erratically may be traced to a poor ground because:

• a.the gauge internally generates its own reference voltage
• b.a bad ground supplies extra reference voltage into the gauge circuit
• c.a grounding condition has no effect at all on gauge accuracy
• d.added ground resistance changes the current the gauge sees✓

Many gauges depend on a stable ground reference; extra resistance in the ground path shifts the circuit values and skews the reading. Cleaning and tightening the instrument-cluster or sensor ground often corrects erratic gauges. Voltage-drop testing the ground confirms the fault.

A vehicle's electrical loads such as headlights, radio, and blower are wired in parallel rather than series so that:

• a.each load receives full system voltage and works independently✓
• b.the source voltage is divided into small shares among the loads
• c.turning off any one load would shut off all the other loads too
• d.all of the loads must always be switched on together at once

Parallel wiring puts each accessory directly across the battery, so every load gets full voltage and one can operate or fail without affecting the others. Series wiring would divide voltage and make the loads dependent on one another. This is why most vehicle circuits are parallel.