ASE B5 Mechanical & Electrical Components flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Thermostat stuck open

Engine warms slowly, heater output stays low, and coolant temperature may drop during highway driving because coolant circulates through the radiator continuously.

Pressure cap function

Seals cooling system and raises coolant boiling point, approximately 3°F per psi, allowing higher operating temperature without boil-over; also allows coolant recovery.

Water pump weep hole

A small drain hole on the pump housing that leaks coolant when the shaft seal fails, preventing coolant from reaching the bearing; leakage indicates replacement is needed.

Coolant air pocket symptoms

Overheating, erratic temperature gauge, no heater output, and gurgling from the heater core can indicate trapped air; bleed the system at bleeder screws or with a funnel.

Combustion gas test

A chemical block test or hydrocarbon detector in the coolant detects exhaust gases; positive results indicate a failed head gasket, cracked head, or cracked block.

Ohm's law

Voltage equals current multiplied by resistance (V = I × R); power equals voltage multiplied by current (P = V × I). Use to calculate expected circuit values.

Battery state of charge

A rested flooded battery reads about 12.6 volts at 100 percent, 12.4 at 75 percent, and 12.2 at 50 percent; recharge before load testing below 12.4 volts.

Voltage drop test

Measure voltage across a circuit or connection while current flows; excessive drop means high resistance. Typical maximum is 0.5 volt for high-current circuits, 0.1 volt per connection.

Parasitic draw limit

After modules sleep, current draw from the battery should typically be 20 to 50 milliamps; higher draw discharges the battery. Use an ammeter or clamp and compare to manufacturer specification.

Alternator charging voltage

A healthy charging system usually produces 13.5 to 14.5 volts at the battery with engine running and loads on; AC ripple should be less than about 0.5 volt.

Brake pedal spongy

A spongy or low pedal usually indicates air in the hydraulic system, a fluid leak, or a faulty master cylinder; bleed the system and inspect for leaks.

Brake fluid hygroscopic

DOT 3 and DOT 4 glycol fluids absorb moisture from the air, lowering boiling point and promoting corrosion; test moisture and replace when contamination exceeds manufacturer limits.

Rotor minimum thickness

Measure rotor thickness with a micrometer at several points; if below the stamped minimum, replace the rotor because it cannot safely absorb heat and may warp or crack.

Lateral runout

Rotor wobble measured with a dial indicator; excessive runout causes pedal pulsation and thickness variation. Compare to manufacturer specification, often around 0.002 inch or less.

Bleeding sequence rule

Unless manufacturer specifies otherwise, bleed the wheel farthest from the master cylinder first, usually right rear, left rear, right front, then left front; keep reservoir full.

Positive caster effect

Positive caster tilts the steering axis rearward at the top, improving straight-line stability and steering return; excessive positive caster increases steering effort.

Negative camber effect

Negative camber tilts the top of the wheel inward, improving cornering grip but causing inner-edge tire wear; excessive negative camber reduces straight-line traction.

Toe wear pattern

Incorrect toe causes feathered tire wear across the tread; toe-in wears outer edges, toe-out wears inner edges. Set total toe and center the steering wheel.

Ball joint check

With the suspension unloaded, check for vertical or horizontal play and listen for clunking; a worn ball joint can cause steering wander and tire wear and must be replaced.

Wheel bearing noise

A worn wheel bearing often growls or hums that changes with vehicle speed and may change when turning; check for play and replace the hub or bearing assembly.

Refrigerant cycle order

Compressor pressurizes vapor, condenser removes heat, expansion valve or orifice tube drops pressure, evaporator absorbs heat, then refrigerant returns to the compressor.

High side versus low side

The high side runs from compressor outlet through condenser to expansion device and is hot and high pressure; the low side runs from evaporator to compressor and is cold and low pressure.

Blower resistor function

The blower resistor or control module reduces current to the blower motor for lower speeds; if only high speed works, the resistor or module is likely open.

No heat diagnosis

If the engine reaches normal temperature but the heater blows cold, check coolant level, heater core flow, blend door operation, and air pockets; both heater hoses should be hot.

Four-stroke cycle

Intake, compression, power, and exhaust strokes occur over two crankshaft revolutions; the camshaft turns once per cycle, at half crankshaft speed.

Torque converter stall test

Hold the brakes, apply full throttle briefly in drive, and compare maximum engine rpm to specification; low stall can indicate a restricted converter or engine power issue.

CV joint failure symptom

A clicking noise during turns, especially at low speed, often indicates a worn outer CV joint; a torn boot loses grease and allows contamination.

Engine mount diagnosis

Worn engine mounts cause vibration at idle, clunking during acceleration, and excessive engine movement; inspect rubber for cracks and check with the engine loaded.

SRS disable procedure

Before servicing SRS, disconnect the battery negative cable and wait the manufacturer-specified time, often 3 to 10 minutes, for the backup power to discharge.

Clockspring function

The clockspring maintains electrical continuity between the steering column and the rotating steering wheel for the driver airbag, horn, and steering wheel controls.

Pretensioner operation

Seatbelt pretensioners use a pyrotechnic charge to retract the belt during a collision, removing slack; they deploy with the airbags and must be replaced after deployment.

SRS lamp on

An illuminated SRS warning means the control module has disabled or detected a fault in the restraint system; retrieve codes with a scan tool before diagnosing.