Your FREE ASE B5 Flashcards 2026 – 200+ Cards

The inward (negative) or outward (positive) tilt of a wheel viewed from the front. Wrong camber wears one tire edge and can pull toward the side with more positive camber.

The forward/rearward tilt of the steering axis viewed from the side. Positive caster gives straight-line stability and steering return; affects handling, not tire wear.

Whether the wheels point in (toe-in) or out (toe-out) viewed from above. Incorrect toe is the biggest cause of rapid, feathered tire wear; it is set last.

A front-suspension unit combining shock and coil spring that also serves as the upper steering pivot. A clunk on turns often means a worn strut bearing.

The bearing at the top of a MacPherson strut that lets it rotate when steered. When worn it causes a clunk or bind during turns.

A suspension link connecting the steering knuckle to the frame/body, locating the wheel while letting it move up and down. A bent arm (collision) throws off alignment.

A pivoting connection between the control arm and steering knuckle. Wear causes play, clunking, and uneven tire wear; a failed one can let the wheel collapse.

The steering link between the steering rack/center link and the knuckle. Wear causes steering play, wander, and toe wear.

The cast part that holds the wheel hub/bearing and connects to the suspension and steering; it pivots to steer the wheel.

A bar linking left and right suspension to resist body roll in turns, keeping the vehicle flatter and improving handling.

The connector between the sway bar and the suspension. A worn link rattles or clunks over bumps.

A damper that controls spring oscillation. Worn shocks cause bouncing, poor ride control, and nose-dive under braking.

A spring that supports vehicle weight and absorbs road shock; a broken or sagging spring changes ride height and alignment.

A layered steel spring used mainly on rear/truck suspensions to support load and locate the axle.

A lateral link that controls side-to-side movement of a solid axle, keeping it centered under the vehicle.

A steering gear where a pinion turns a toothed rack to move the tie rods, converting wheel rotation into side-to-side wheel movement.

A belt-driven pump that supplies hydraulic pressure to assist steering. A whining noise often means low fluid or a failing pump.

Steering assist from an electric motor instead of a hydraulic pump, using a torque sensor to gauge driver effort.

A sensor that measures steering effort so the EPS motor applies the right amount of assist.

An unwanted change in toe as the suspension moves up and down, often from bent or worn steering/suspension parts after a collision.

The bearing that lets the wheel hub spin freely. A failing bearing growls or hums and the noise changes with speed or cornering load.

The assembly the wheel bolts to, carrying the bearing and (often) the wheel-speed sensor.

Tire Pressure Monitoring System — warns of low tire pressure via wheel sensors (direct) or wheel-speed data (indirect); often needs a relearn after service.

A TPMS that uses a pressure sensor inside each wheel; replacing a sensor or rotating wheels may require a relearn.

Adjusting camber, caster, and toe to spec so the vehicle tracks straight and tires wear evenly; required after structural collision repair.

The direction the rear axle points relative to the vehicle centerline; a bad thrust angle makes the vehicle 'dog-track' or pull.

When one front wheel sits farther back than the other, often from collision damage, causing a pull and alignment trouble.

The bushings securing the steering rack to the body; loose mounts cause clunks and vague steering.

Parts of a parallelogram steering linkage; the pitman arm is driven by the gearbox and the idler arm supports the other end.

The steering link that connects the pitman and idler arms to the tie rods in a parallelogram steering system.

The body structure the top of a strut mounts to; a shifted tower from a collision changes camber and caster.

The designed distance from the body to the ground; sagging springs lower it and alter alignment angles.

A wear pattern with one side of each tread block higher than the other, caused by incorrect toe.

Scalloped tire wear from worn shocks/struts or a bad wheel bearing letting the tire bounce.

An independent suspension using upper and lower control arms (wishbones) to locate the wheel with good camber control.

A suspension arm that controls side-to-side wheel location in an independent rear suspension.

A steering rack whose ratio changes with wheel angle, giving easy parking and stable highway response.

A sensor that reports steering-wheel position to stability control and ADAS; it often needs a relearn after alignment or repair.

Electrical pressure (potential difference) that pushes current through a circuit, measured in volts.

The flow of electric charge through a circuit, measured in amperes (amps).

Opposition to current flow, measured in ohms. High resistance from corrosion or loose grounds causes dim or intermittent operation.

Voltage = current × resistance (V = I × R). It ties together the three basic electrical quantities.

A circuit with one path; the same current flows through every component and voltage divides across them.

A circuit with multiple paths; voltage is the same across each branch and current divides between them.

A break in the path so no current flows; the device is completely dead.

An unintended path letting current flow straight to ground, bypassing the load; it usually blows the circuit's fuse.

An unintended connection between circuits or to a power feed that can overload and damage components.

The voltage lost across a wire, connection, or load. Excess drop signals high resistance such as corrosion or a loose ground.

Measuring volts lost across a segment while current flows, by placing meter leads across it under load — finds high resistance a key-on check misses.

A meter that reads voltage, resistance, and current; the core tool for electrical diagnosis.

To read resistance correctly the circuit must be de-powered, or the meter reading is wrong.

A sacrificial device that melts to break a circuit when current exceeds its rating, protecting the wiring.

A short length of smaller-gauge wire that melts to protect a high-current circuit, acting like a heavy-duty fuse near the battery.

A resettable overcurrent device that opens on overload and can be reset (manually or automatically).

An electrically operated switch that uses a small control current to switch a large load current.

A relay switches a circuit on/off; a fuse only protects it from overcurrent — they do different jobs.

A one-way valve for current; it allows flow in one direction and blocks the reverse, used for rectification and spike suppression.

Diodes in the alternator that rectify AC to DC; heat and vibration cause failure, often signaled by AC ripple in the output.

Stores chemical energy and supplies DC to start the engine and run electronics when the engine is off.

How full a battery is; measured by voltage or with a tester. A fully charged 12-V battery reads about 12.6 V at rest.

The belt-driven generator that charges the battery and powers the electrical system while the engine runs.

Checks that the alternator maintains roughly 13.5–14.5 V at the battery under load with no excessive AC ripple.

The high-current motor that cranks the engine; a slow crank can be a weak battery or high resistance in the starter circuit.

The metal return path that completes a circuit back to the battery; a corroded ground causes many odd electrical faults.

Current drawn with the key off; an excessive draw drains the battery overnight.

Controller Area Network — a serial data network letting modules share information over a twisted pair, ended by terminating resistors.

A resistor (typically 120 ohms) at each end of a CAN bus that prevents signal reflections and keeps data readable.

A computer that monitors sensors and controls outputs; vehicles have many networked modules.

A sensor that produces a digital on/off signal as a magnetic field passes, used for speed and position sensing.

A sensor that generates an AC voltage as a toothed wheel passes, used for crank, cam, and wheel-speed sensing.

Switching a circuit on and off rapidly and varying the on-time to control output like motor speed or lamp brightness.

Diagnostic Trouble Code — a code a module stores when it detects a fault, read with a scan tool to guide diagnosis.

A diagnostic (health) scan before collision work to document existing trouble codes and create a baseline.

A scan after collision work to confirm codes are cleared, no new faults appeared, and which systems need calibration.

Advanced Driver-Assistance Systems — cameras, radar, and sensors (lane keeping, auto braking) that must be calibrated after collision repair disturbs them.

Aiming and relearning ADAS cameras/radar to OEM spec after repair so the systems read the road correctly.

Disconnect the negative terminal first to de-power airbags and protect modules before welding/pulling; reconnect it last.

Repair damaged harnesses with proper splices/connectors and protect them from heat, sparks, and pulling forces during repair.

Adjusting headlight beams to spec after front-end repair so they light the road without blinding oncoming drivers.

On hybrids/EVs, the system that monitors and balances high-voltage battery cells and manages charging and temperature.

Converts brake-pedal force into hydraulic pressure sent to the wheel brakes.

A master cylinder with two pistons feeding two independent circuits so braking remains if one circuit leaks.

A hydraulic fluid that transmits pedal force; it is hygroscopic (absorbs water), which lowers its boiling point over time.

A soft, low pedal caused by air in the hydraulic lines or a fluid leak; it needs bleeding or leak repair.

Removing air from the hydraulic system to restore a firm pedal after any brake-line or component repair.

Limits hydraulic pressure to the rear brakes during hard stops to keep the rear wheels from locking before the fronts.

A brake using a caliper to squeeze pads against a rotor; good at shedding heat and resisting fade.

The clamp that presses the pads against the rotor; a sticking caliper drags and causes a pull and uneven wear.

The spinning disc the pads clamp; a warped rotor causes a pulsing pedal and steering-wheel shudder.

An out-of-flat or thickness-varying rotor that causes a pulsing brake pedal and vibration when braking.

Friction material pressed against the rotor; uneven pad wear points to a sticking caliper or slide pins.

A brake using shoes that press outward against a spinning drum, common on rear axles of lighter vehicles.

A vacuum (or hydraulic) assist that multiplies pedal force so braking takes less effort.

A vehicle that veers when braking, usually from a dragging caliper or contaminated pad on one side.

Anti-lock Braking System — keeps wheels from locking during hard braking using wheel-speed sensors and a hydraulic modulator.

Reads each wheel's rotational speed for ABS and stability control; a damaged sensor or tone ring sets a fault.

The toothed ring a wheel-speed sensor reads; a bent or damaged ring after a collision causes erratic readings.

The hydraulic unit that rapidly releases and reapplies brake pressure to a wheel to prevent lockup.

Builds on ABS, using steering-angle and yaw inputs to brake individual wheels and keep the vehicle on its path.

A parking brake applied by an electric motor/actuator instead of a cable and lever.

A dual circuit pairing one front and the opposite rear wheel per circuit so one failure still leaves braking on both ends.

Reports hydraulic pressure to the ABS/stability module; a faulty sensor can disable ABS and set a code.

The fluid (R-134a or R-1234yf) that absorbs and releases heat as it cycles through the A/C system; it must be recovered, not vented.

A low-global-warming refrigerant used in newer vehicles, replacing R-134a; it requires its own service equipment.

Pumps and compresses low-pressure refrigerant vapor into a hot, high-pressure gas, driving the refrigerant loop.

The front-mounted heat exchanger where the hot high-pressure gas sheds heat and condenses into a liquid; often damaged in front collisions.

The dash heat exchanger where cold low-pressure refrigerant absorbs heat from cabin air, cooling the air the blower delivers.

A fixed-size metering restriction (used with an accumulator) that drops refrigerant pressure before the evaporator.

A variable metering valve (used with a receiver-drier) that adjusts refrigerant flow based on evaporator temperature.

Stores refrigerant and removes moisture with a desiccant in TXV systems, on the high side.

Stores refrigerant and removes moisture in orifice-tube systems, on the low side, protecting the compressor from liquid.

A moisture-absorbing material inside the receiver-drier or accumulator that keeps water out of the refrigerant.

The A/C loop split by the metering device into a hot high-pressure side (compressor to metering) and a cold low-pressure side (metering to compressor).

Capturing refrigerant with approved equipment before opening the system; venting it is illegal and harmful.

Pulling a vacuum on the A/C system to remove air and boil off moisture before recharging.

Refilling the A/C with the correct refrigerant type and exact specified amount after service.

The federal rule requiring certified technicians and approved equipment to service motor-vehicle A/C systems.

An air door in the HVAC case that mixes heated and cooled air to set cabin temperature; a stuck actuator gives wrong temperatures.

An HVAC door that directs airflow to the vents, floor, or defrost; a failed mode-door actuator misroutes airflow.

A small electric motor that moves a blend or mode door; a faulty actuator clicks or sets the wrong temperature/airflow.

A small radiator in the dash that uses engine coolant to heat the cabin; a leak fogs the windshield with sweet-smelling vapor.

A filter that cleans incoming HVAC air; when clogged it reduces airflow from the vents.

A temperature-sensitive resistor used to sense cabin or evaporator temperature for climate control.

A sensor that detects sunlight intensity so automatic climate control compensates for solar heating.

Ice on the evaporator from excess moisture or a stuck-low temperature, which blocks airflow and cuts cooling.

A/C that cools well at speed but poorly at idle usually points to weak airflow over the condenser (fan) or low idle performance.

A temperature-controlled valve that blocks coolant flow to the radiator until the engine warms, then opens to regulate temperature.

Blocks flow to the radiator, causing the engine to overheat.

Lets coolant flow too soon, keeping the engine too cool and weakening cabin heat and economy.

The belt- or chain-driven pump that circulates coolant through the engine and radiator.

The heat exchanger where airflow sheds heat from the coolant; often damaged in a front collision.

A pressure cap that seals the system and raises the coolant boiling point; its vacuum valve returns coolant from the recovery tank.

A water/glycol mix that transfers heat, resists freezing and boiling, and protects against corrosion.

Usually a 50/50 coolant-to-water mix; the wrong ratio reduces freeze/boil protection and corrosion resistance.

Holds expanding coolant and returns it as the engine cools, keeping the system full and air-free.

An electric or clutch-driven fan that pulls air through the radiator at low speed and idle.

A thermostatic coupling that engages the engine-driven fan when the radiator is hot.

Trapped air after a refill that blocks coolant flow and causes localized overheating even with no leaks; bleed the system.

Applying pressure to the system to find external leaks or a cap that won't hold pressure.

A test that detects exhaust gases in the coolant, confirming a head-gasket or cracked-head leak.

Part of the cooling circuit; a heater control valve or core directs hot coolant for cabin heat.

Displays engine coolant temperature; a steady climb past normal warns of overheating.

Low coolant, a stuck thermostat, a failed water pump or fan, a clogged radiator, an airlock, or a head-gasket leak.

Indicates internal corrosion or old/contaminated coolant; the system should be flushed and refilled with fresh coolant.

Draining and cleaning the system to remove rust, scale, and old coolant, then refilling with the correct mix.

A small drain hole on the pump; coolant leaking from it signals a failing pump seal.

A fluid coupling connecting the engine to an automatic transmission; it idles, multiplies torque at low speed, and locks up at cruise.

A clutch that mechanically links the converter at cruising speed to eliminate slip and improve fuel economy.

The plate that bolts the torque converter to the crankshaft; a crack causes a noise that changes with load.

A gearbox that shifts gears automatically using hydraulics, clutches, and (in many) planetary gearsets.

A driver-shifted gearbox using a clutch to connect and disconnect engine power.

The driver-controlled coupling in a manual transmission that connects and disconnects engine power for shifting.

A device in a manual transmission that matches gear speeds for smooth, quiet shifting; worn synchros cause grinding.

A whining noise from worn gears, low fluid, or improper gear mesh in a transmission or differential.

An automated manual using two clutches for fast, smooth shifts without a torque converter.

A gearset that splits drive torque to the wheels while letting them turn at different speeds in a corner.

A differential that sends torque to the wheel with grip when one wheel slips, improving traction.

A constant-velocity joint that lets a drive axle deliver power smoothly while the wheel steers and travels.

The rubber boot that holds grease in and dirt out of a CV joint; a tear leads to a clicking, failing joint.

A rhythmic click that gets louder when turning at low speed — the classic sign of a worn outer CV joint.

The shaft with CV joints that delivers power from the differential to a front (or independent rear) wheel.

A joint on a driveshaft that allows angle changes; wear causes a clunk on acceleration and a speed-related vibration.

The shaft carrying power from the transmission to the rear axle; an unbalanced shaft vibrates at higher speeds.

A vibration that rises with vehicle speed, often from a worn U-joint or an unbalanced/bent driveshaft.

A gearbox in 4WD/AWD that splits power between the front and rear axles.

An AWD device that transfers torque between axles using fluid shear; a failure causes binding or lost AWD.

A mount that supports the transmission and dampens vibration; a broken mount lets the drivetrain shift and clunk.

Checking axles, joints, boots, mounts, and the driveline for damage and leaks after a collision.

Measures oxygen in the exhaust and tells the computer if the mixture is rich or lean for closed-loop fuel control near 14.7:1.

An exhaust device that converts carbon monoxide, hydrocarbons, and NOx into less harmful gases; a plugged one kills power.

A colorless, odorless, poisonous exhaust gas; a crash-damaged exhaust can leak it into the cabin — a key safety check.

Measures the air entering the engine so the computer can meter fuel; a faulty MAF causes poor running and drivability codes.

Maintains the correct fuel-rail pressure for the injectors; a fault causes rich or lean running.

An electronic valve that sprays metered fuel into the intake or cylinder; a clogged or leaking injector skews the mixture.

Sprays fuel directly into the cylinder at high pressure, using a high-pressure fuel pump for efficiency and power.

Exhaust Gas Recirculation valve — routes inert exhaust into the intake to lower combustion temperature and cut NOx.

An exhaust-driven compressor that forces more air into the engine for more power.

A heat exchanger that cools the compressed intake air from a turbocharger, increasing air density and power.

Filters intake air; a clogged filter restricts airflow and can richen the mixture and cut power.

Checking fuel lines and the tank for leaks and damage after a crash — a fuel leak is an immediate fire hazard.

A crushed or plugged exhaust that chokes the engine, causing power loss especially at higher RPM.

A crack or loose joint that lets exhaust escape; near the cabin it is a carbon-monoxide hazard and must be repaired.

The airbags, seat-belt pretensioners, crash sensors, and control module that protect occupants in a crash, supplementing the seat belts.

An inflatable cushion that deploys in a crash to cushion the occupant; a deployed bag must be replaced, never reused.

The computer that reads crash sensors and deploys airbags and pretensioners; it stores crash and fault data.

Detects the rapid deceleration of a collision and signals the SRS module to deploy the restraints.

Detects a vehicle tipping over so the SRS can deploy side curtains and tension the belts.

A one-time pyrotechnic/mechanical device that instantly retracts the belt in a crash to remove slack before the airbag inflates.

A fired pretensioner is a one-time device and must be replaced, not reset, after deployment.

A coiled ribbon that keeps the driver-airbag and steering-wheel circuits connected as the wheel turns.

An airbag that deploys from the seat or door for side crashes, protecting the torso or pelvis.

A roof-rail airbag that drops to cover the side windows, protecting the head in side impacts and rollovers.

The spool that takes up belt slack and locks in a crash; a faulty retractor won't lock or retract properly.

A seat sensor that detects occupant weight/presence so the system can enable or suppress the passenger airbag.

Disconnect the battery and wait the manufacturer-specified time before working near airbags to prevent accidental deployment.

Carry the module with the cover facing away and set it face-up; it is an explosive device handled per the OEM procedure.

Deploying or disposing of live airbags only per OEM/manufacturer and regulatory procedures.

A dash light that, when lit, means a stored restraint-system fault that must be scanned and repaired.

The headrest positioned so its top is near the top of the occupant's head to reduce whiplash in a rear impact.

Scanning the restraint system after repair to confirm no faults remain before returning the vehicle.