ASE A6 practice test, every option explained

Incorrect: Unplugging module B leaves the reading at 40 Ω.

Incorrect: The reading stays at 40 Ω with module A unplugged.

Incorrect: A wiring fault would not clear when a single module is unplugged.

Correct: 40 Ω means a third terminator is present; unplugging module C restores 60 Ω, so C carries an extra terminating resistor.

Incorrect: The reading stays at 40 Ω without module D.

Incorrect: A dead meter battery gives no reading or an error, not a false low value.

Incorrect: A short to power gives an erratic or damaging reading, not a clean low resistance through an open wire.

Correct: With the module still connected, the meter's test current found a path through its internal circuits and hid the open.

Incorrect: Lead resistance is a fraction of an ohm and cannot hide an open.

Incorrect: A poor probe connection raises the reading; it cannot make an open look low.

Incorrect: 0.05 A drops the 150 mA infotainment draw from the total.

Incorrect: 0.18 A leaves out the cluster's 0.02 A, and 0.18 A would still be over 50 mA.

Correct: 150 mA + 20 mA + 30 mA = 200 mA, or 0.20 A, four times the 50 mA limit.

Incorrect: 2.00 A is ten times the real total; 200 mA is 0.20 A.

Incorrect: 1.55 A comes from reading 150 mA as 1.5 A.

Correct: Circuit B alone is 35 mA, over the 30 mA limit; fixing it leaves 15 mA, within spec.

Incorrect: The 50 mA total exceeds the 30 mA specification.

Incorrect: Fixing circuit A still leaves 35 mA, above the limit.

Incorrect: Circuit A's 15 mA fits inside the allowance, so only B needs repair.

Incorrect: The battery is the victim of the draw, not its cause.

Incorrect: Replacing a harness without locating the fault is costly and may still miss it.

Incorrect: Running an overlay wire before finding the fault is a guess.

Incorrect: A static resistance check will likely read normal while the short is absent.

Correct: The fault shows up on rough roads, so the harness is flexed while a scope watches for the dropout.

Incorrect: A short-to-ground code points to the circuit, not the module.

Correct: ECM–TCM and ABS–BCM each talk, but nothing crosses from the TCM side to the ABS side, so the break lies between them.

Incorrect: The matrix tests module-to-module paths, and the failures are between modules.

Incorrect: ABS and BCM communicate, so that segment is intact.

Incorrect: ECM and TCM communicate, so that segment is intact.

Incorrect: The ABS module still talks to the BCM, so it works.

Incorrect: Checking voltage at the motor connector is the right place.

Incorrect: 12.6 V at the connector shows the fuse was good.

Correct: An ohmmeter on a live circuit gives a false reading, so the 0.2 Ω 'good ground' proved nothing.

Incorrect: Voltage reached the motor connector, so the switch was not the issue.

Incorrect: Reviewing the schematic first is good practice, not an error.

Incorrect: Technician A is wrong: an open suppression diode leaves the coil reading unchanged, so coil ohms can look perfect.

Correct: Technician B is right: an open diode does not change coil resistance, so it is checked with the meter's diode test.

Incorrect: Technician A's claim is wrong, so both cannot be right.

Incorrect: Technician B's diode test is the correct way to check the suppression diode.

Incorrect: Shorted lines show no differential at all, not correct dominant levels.

Incorrect: The recessive and dominant levels are correct, so bias is not the problem.

Incorrect: Normal levels rule out weak signals.

Incorrect: An open line distorts or loses one signal; it would not keep both at correct levels.

Correct: Proper levels with ringing at the edges point to reflections, from wrong termination or long stubs.

Incorrect: A short to ground would hold the bus low, not at 15.8 V.

Incorrect: A short to power would hold the bus high and block the 1.2 V dominant state.

Correct: LIN recessive voltage follows system voltage, and 15.9 V means overcharging; the master pulls the bus low normally.

Incorrect: The bus reaches 1.2 V in the dominant state, so the master pulls it down.

Incorrect: At 12.65 V the battery is already charged, so more charging will not restore capacity.

Incorrect: Equalizing does not fix a charged battery that fails capacity tests.

Incorrect: A draw test explains discharge; this battery is charged and still weak.

Correct: It is fully charged yet fails both conductance and load tests, so it lacks capacity.

Incorrect: These are battery tests; nothing here measures alternator output.

Incorrect: Undercharging causes sulfation, not swelling.

Incorrect: A loose hold-down causes vibration damage, not a swollen case.

Correct: Overcharging overheats the battery and gasses the electrolyte, which swells the case.

Incorrect: Age reduces capacity but does not swell the case by itself.

Incorrect: MCA is cranking current at 32°F, not a runtime rating.

Incorrect: CCA is current for 30 seconds at 0°F, a cranking rating.

Correct: Reserve capacity is the minutes a battery can carry a 25 A load, roughly how long it runs accessories if charging fails.

Incorrect: Amp-hours describe capacity over a 20-hour discharge, not minutes at 25 A.

Incorrect: Thick cold oil does raise cranking load, but a weaker cold battery is also a valid cause.

Incorrect: Reduced CCA is a valid cause, but thick cold oil also slows cranking.

Correct: Both are right: cold thickens the oil and raises the load while battery output drops.

Incorrect: Cold-weather slow cranking is the classic result of thick oil and reduced CCA.

Incorrect: Starting with negatives and finishing on a positive post puts the spark at a battery.

Incorrect: The negative clamp goes on the dead battery's post, inviting a spark near battery gas.

Correct: Positives first, dead then good, then negative on the good battery, and the last clamp on a ground away from the dead battery.

Incorrect: Connecting ground first and finishing on a battery post reverses the safe order.

Incorrect: An ammeter measures current, not internal resistance.

Incorrect: A voltmeter alone shows voltage, not internal resistance.

Correct: A conductance tester sends a small AC signal through the battery and calculates internal resistance and estimated CCA.

Incorrect: A hydrometer reads electrolyte specific gravity, which reflects charge.

Incorrect: A bad solenoid usually clicks or fails to engage rather than grinding.

Incorrect: Low voltage causes slow cranking or clicking, not grinding.

Correct: Grinding during engagement is gear teeth failing to mesh, from a worn pinion or damaged ring gear.

Incorrect: A shorted field coil slows cranking but does not grind the gears.

Incorrect: A DMM's internal ammeter tops out near 10 A, far below alternator output.

Correct: A carbon pile loads the system so the alternator reaches full output, read with an inductive amp clamp.

Incorrect: A hydrometer reads electrolyte, not alternator output.

Incorrect: A test light shows only that voltage is present.

Correct: A weak tensioner lets the belt slip now and then, so it chirps and charging output rises and falls.

Incorrect: High coolant temperature points to a cooling problem.

Incorrect: A check engine lamp is a generic engine warning and does not point to the tensioner.

Incorrect: Oil pressure has nothing to do with belt tension.

Incorrect: Fuse box connections come later; a slipping belt is the most common cause.

Incorrect: Electrolyte level does not make the charge lamp flicker.

Incorrect: Starter draw has nothing to do with a charge warning while driving.

Correct: A slipping belt drops output for a moment and flickers the charge lamp, so the belt is the quick first check.

Incorrect: A bulb cannot let moisture into the housing.

Incorrect: Humid air is always around, but it collects inside only when a seal has failed.

Incorrect: Aim decides where the beam points, not whether water gets in.

Correct: Moisture builds up when the housing seals or vents fail and let humid air in.

Correct: The dimmer is often simply turned down, so its setting is checked before any testing.

Incorrect: Low system voltage would dim more than the dash lights.

Incorrect: The headlight switch is suspected only after its dimmer setting is ruled out.

Incorrect: A blown fuse would turn the dash lights off, not dim them.

Incorrect: Resistance at a switch ground dims the lamp with a door open; it cannot light it with the doors closed.

Incorrect: Open switches are normal with the doors closed and leave the lamp off.

Incorrect: Battery voltage on both sides of the bulb leaves nothing across it, so the lamp stays off.

Correct: A resistive path to ground on the wire between lamp and switches lets some current flow with the switches open, so the lamp glows dimly.

Incorrect: A switch shorted to ground lights the lamp at full brightness, not dimly.

Incorrect: A burned filament is an open circuit, not a short.

Incorrect: A burned filament simply opens, and the glass stays intact.

Correct: Each filament has its own feed and shares only the ground, so one can fail while the other still lights.

Incorrect: The filaments are independent, so losing one does not kill the other.

Incorrect: The charging system regulator sets system voltage, not HID arc power.

Incorrect: A bare transformer cannot regulate the arc after start-up; the ballast does both jobs.

Incorrect: A resistor cannot produce the thousands of volts needed to strike the arc.

Correct: The HID ballast creates the high ignition voltage and then regulates the arc current.

Incorrect: The interior switch is the part that works.

Correct: The locks work from the switch and two good fobs both fail, so the receiver is not picking up the fob signal.

Incorrect: The actuators work from the interior switch.

Incorrect: Power reaches the locks, because the switch operates them.

Incorrect: A wrong tire size setting makes the reading consistently off, not intermittent.

Incorrect: The needle sweeps normally in the self-test, so the stepper motor works.

Incorrect: A blown cluster fuse would kill every gauge, not make one drop out now and then.

Correct: The speedometer reads a vehicle speed sensor, so a loose or corroded sensor connection makes it drop out.

Incorrect: Tape loosens and lets water in, especially in a door that flexes.

Incorrect: Wire nuts are household parts that loosen with vibration.

Correct: A soldered splice sealed with adhesive heat shrink restores conductivity and keeps moisture out.

Incorrect: Twisting without a proper crimp sleeve or solder leaves a loose, unsealed joint.

Incorrect: The ground is tested once the fuse and feed check out.

Incorrect: With no control module there are no codes to read.

Incorrect: Testing the motor comes after power is confirmed at it.

Correct: On a simple circuit a blown fuse or missing voltage is the quickest thing to rule in or out.

Correct: The SRS module stores energy that can fire an airbag, so the battery is disconnected and the manufacturer's wait time observed.

Incorrect: Grounding test points could fire an airbag.

Incorrect: A scan tool cannot make the system safe to service.

Incorrect: Pulling only the fuse leaves the reserve energy in the module.

Incorrect: The meter reads 12.6 V to the connector's ground terminal, so ground is good.

Correct: Full voltage across feed and ground with no heat means the element itself is open, often a broken wire in the cushion.

Incorrect: Voltage at the connector shows the fuse is intact.

Incorrect: The relay is passing power to the connector.

Correct: The siren and system work from the hood input, so the door input switch is not reporting.

Incorrect: The siren sounds for the hood, so it works.

Incorrect: The fob arms and disarms the system; it does not detect doors opening.

Incorrect: A blown fuse would disable the whole alarm, hood included.

Incorrect: A blown fuse would stop movement in every direction.

Incorrect: A module fault is unlikely when one direction works.

Correct: One direction works, so power, ground and motor are fine, leaving the switch contacts for the other direction.

Incorrect: The motor runs one way, and its reverse direction depends on the polarity the switch supplies.

Incorrect: A blown fuse would keep the door from starting at all.

Incorrect: The switch starts the travel; stopping midway points to something blocking it.

Correct: Stopping mid-travel is often obstacle detection reacting to debris in the track.

Incorrect: The motor moves the door partway, so it runs.

Correct: After a power loss the module forgets the window's end points and disables express-up until the relearn is done.

Incorrect: The motor drives the window normally.

Incorrect: A broken regulator would stop or bind normal travel too.

Incorrect: The switch moves the window both ways, so it works.

Incorrect: Several motors failing intermittently at once is unlikely.

Incorrect: Software does not change because water got in.

Correct: Water intrusion followed by intermittent faults in several systems points to corrosion at the harness connectors they share.

Incorrect: A switch affects its own system, not seats, windows and mirrors together.

Incorrect: Eye protection is good shop practice, but the risk specific to a cluster is static discharge.

Incorrect: There are no chemicals to guard against when handling a cluster.

Incorrect: Heat is not a hazard when handling a cluster.

Correct: Electrostatic discharge (ESD) can damage a cluster's circuits, so it is handled with a grounded wrist strap or other anti-static protection.

Incorrect: Every motor moves the seat, so they work.

Incorrect: A damaged track would bind movement, and the seat moves normally.

Correct: Memory depends on position sensors in the motors, so a failed sensor leaves nothing to store.

Incorrect: The module is powered and communicating, so its fuse is good.

Incorrect: The scan tool only reads the counters; it does not cause errors between modules.

Incorrect: A fault in one module would mostly raise that module's counters, not every module's.

Incorrect: A TCM software problem would not raise errors on every module.

Correct: High error counters on every module point to something they all share: bus wiring, terminations or connectors.

Incorrect: CAN arbitration settles priority without errors, so heavy traffic does not push counters to bus-off.

Incorrect: A stuck relay keeps the blower running and drawing, not stopping after five minutes.

Correct: Many vehicles wake hours after shutdown to run a key-off EVAP leak check, which draws current briefly and returns to sleep.

Incorrect: A solenoid short would crank or heat the starter, not draw 1.8 A for five minutes and stop.

Incorrect: Battery resistance does not create a timed current spike through the ammeter.

Incorrect: A stuck trunk lamp switch would draw steadily all night instead of returning to 35 mA.

Incorrect: Surface charge cannot cause a 250 mA draw, and the draw is already gone.

Incorrect: A larger fuse removes protection and does nothing about a module that stays awake.

Correct: The draw vanished after a power reset and stayed gone, the pattern of a radio that failed to sleep, so a software fix or bulletin is checked next.

Incorrect: The draw followed the radio fuse, not the BCM.

Incorrect: A harness fault would return with the fuse, and the draw did not.

Incorrect: Current rises only when resistance falls or voltage rises.

Incorrect: The stem holds voltage constant; resistance does not create voltage.

Correct: With voltage fixed, I = V ÷ R, so more resistance means less current.

Incorrect: At a fixed voltage, current changes whenever resistance changes.

Incorrect: Brushes carry current to the commutator; they do not disengage the drive.

Incorrect: Field coils create the magnetic field and give no overspeed protection.

Correct: The overrunning (one-way) clutch lets the pinion freewheel once the engine fires, so the flywheel cannot spin the armature to destructive speed.

Incorrect: The armature is the part being protected, not the protection.

Incorrect: Leaving the sensor off gives the PCM a false temperature and a wrong charging voltage.

Incorrect: On the engine it would read engine heat, not battery temperature.

Correct: The charging system reads this sensor to set target voltage, so it goes back exactly where it was, against the new battery.

Incorrect: The sensor does not wear out with the battery; it is reused unless it tests bad.

Correct: The solenoid plunger pulls the shift fork that moves the pinion into the flywheel ring gear, then closes the motor contacts.

Incorrect: Field coils create the magnetic field the armature turns in.

Incorrect: The armature is the rotating part that turns the pinion; it does not shift it into mesh.

Incorrect: The commutator feeds current to the armature windings through the brushes.

Incorrect: Heat shields and placement manage battery heat, not the vent tube.

Correct: The tube carries hydrogen and acid vapor out of the battery box, away from sparks and the cabin, which matters in trunk and under-seat installs.

Incorrect: Only the voltage regulator controls charging; a vent tube changes nothing about it.

Incorrect: The tube is far too small to move cooling air; it only carries gas out.

Incorrect: A slipping belt slows the rotor, but the field circuit itself stays intact.

Incorrect: The stator is the output winding; an open there cuts output without touching the field circuit.

Incorrect: A shorted diode affects the output stage, not the current through the rotor field.

Correct: The brushes carry field current to the rotor through the slip rings, so worn brushes open the field circuit and cut output.

Incorrect: A thermal switch senses temperature and does not protect a lamp circuit.

Correct: A relay carries the high lamp current, and a fuse protects the wiring.

Incorrect: A fuse alone would route lamp current through the dash switch, which is why a relay is added.

Incorrect: Circuit breakers suit motor circuits such as power windows, not fog lamps.

Incorrect: Wi-Fi serves hotspots and software downloads, not module-to-cluster data.

Incorrect: Bluetooth links phones to the infotainment system, not modules to the cluster.

Incorrect: USB connects devices to the infotainment system; modules do not use it to talk to the cluster.

Correct: The cluster receives speed, engine and warning data from other modules over the CAN network.