ASE T8 Preventive Maintenance Inspection (Medium/Heavy Truck) flashcards

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

Out-of-service brake threshold

A vehicle is out of service when 20 percent or more of its brakes are defective by pushrod stroke or lining condition under the North American Standard criteria.

Lockout tagout purpose

Isolating and locking an energy source so the equipment cannot be re-energized while a technician is servicing it, with the key held by that technician.

Hearing protection threshold

Hearing protection is required when noise exposure reaches an 8-hour time-weighted average of 85 decibels in the workplace.

DVIR retention period

Driver vehicle inspection reports must be retained by the carrier for at least three months from the date the report was written.

Annual inspection interval

Every commercial vehicle must receive a documented periodic inspection at least once every 12 months by a qualified inspector.

DVIR defect certification

Before a vehicle with a reported defect is operated again, the carrier must certify in writing that the defect was repaired or is unnecessary to safe operation.

Hood secondary catch

A backup latch that must independently hold the hood closed if the primary latch releases, preventing the hood from opening into the windshield.

Defroster inspection point

The defroster must deliver air across the windshield and clear it; failure to clear the glass is a defect in cold-weather operation.

Cab mount inspection

Cab isolators and mounts are checked for cracks, elongation, and missing fasteners, since loose mounts cause steering wander and clutch complaints.

Battery load test limit

At 70 degrees Fahrenheit, a battery that drops below 9.6 volts during a 15-second load at half its cold cranking amps is defective.

Parasitic draw limit

After all modules enter sleep mode, current draw above roughly 50 milliamps indicates a fault requiring circuit isolation.

Voltage drop specification

Testing a circuit under load, a drop greater than 0.5 volt on a power or ground path indicates excessive resistance at a connection or cable.

CAN bus resistance check

With the key off, a healthy J1939 data bus measures about 60 ohms across CAN high and CAN low at the diagnostic connector.

Clutch free play

The measured travel before the release bearing contacts the clutch fingers; too little causes slipping, too much causes incomplete release and hard shifting.

Driveshaft phasing

On a two-piece driveshaft, the U-joint yokes at each end of the shaft must align in the same plane to prevent road-speed vibration.

Differential fill level

With the vehicle level, gear lubricant is filled at the plug hole until fluid just reaches the bottom of the opening.

Coolant in engine oil

A milky oil appearance indicates coolant intrusion from a failed oil cooler, head gasket, or liner seal and requires diagnosis before further service.

Fifth wheel tug test

After coupling, apply trailer brakes and pull against them to confirm the kingpin is locked and the release handle safety latch is engaged.

Air tank drain purpose

Opening tank drain valves purges condensed moisture; recurring water accumulation points to an air dryer or compressor fault.

Exhaust leak hazard

A leak ahead of or under the cab allows carbon monoxide into the cab; hangers and clamps must support the system leak-free.

Steering wheel free play

With wheels straight ahead, free play measured at the rim of a 20-inch steering wheel should not exceed approximately 2 inches.

Pushrod stroke measurement

Measure with full brake application and compare the stroke to the slack adjuster limit for that chamber size to determine if adjustment is needed.

Brake lining minimum

Air drum brake lining at the center of the shoe must be at least 1/4 inch (6 mm); less is an out-of-service condition.

Air leak test limit

With the engine off and brakes applied, a single vehicle should lose no more than 3 psi per minute from the air system.

Compressor build-up time

At governed engine speed, the air system should build from 85 to 100 psi in approximately 45 seconds on a properly functioning compressor.

Automatic slack adjuster rule

An automatic slack adjuster that will not hold adjustment within stroke limits must be replaced rather than repeatedly readjusted.

Coolant freeze point test

A refractometer reading of a 50/50 glycol mix should protect to about -34 degrees Fahrenheit; weaker mixes risk freezing and corrosion.

DEF quality standard

Diesel exhaust fluid must meet ISO 22241; contaminated or diluted DEF causes aftertreatment faults and engine derate.

Water separator service

The fuel filter water separator is drained daily, since water reaching the high-pressure fuel pump causes costly internal damage.

Oil analysis trending

Tracking iron, copper, and silicon in oil samples over time reveals wear metals and dirt ingestion before a failure occurs.

Air filter restriction rule

Replace a paper air filter element when restriction reaches the manufacturer's limit; do not clean and reuse paper elements.

Grease fitting service

Pump grease into steering, suspension, and driveline fittings until clean grease appears, avoiding excess pressure that can rupture seals.