The ASE T8 Preventive Maintenance Inspection (PMI) test is a great first T-Series certification. It covers the whole truck from bumper to mud flaps, and it tests the inspection skills shops use every day: spotting a problem before it turns into a breakdown, a roadside violation or a crash.
Here’s what’s on the T8, where the points are and how to study for it.
The T8 test at a glance
The T8 has about 50 scored questions, plus around 10 unscored research questions, with about 75 minutes to finish. Frame and chassis is the biggest section by far, so spend your study time there.
| Content area | Share of test | About how many questions |
|---|---|---|
| A. Engine Systems | 20% | 10 |
| B. Cab and Hood | 10% | 5 |
| C. Electrical/Electronics | 20% | 10 |
| D. Frame and Chassis | 44% | 22 |
| E. Road/Operational Test | 6% | 3 |
Like the other T-Series tests, you need two years of hands-on work experience to be certified, and a diesel program can count for up to one year. Registration is $34 per order plus $62 per test.
A. Engine Systems (about 10 questions)
- Fluids: oil level and condition, coolant level, freeze protection checked with a refractometer, and coolant additive (SCA) levels with test strips.
- Belts and hoses: cracks, glazing, tension and tensioner operation. Soft, swollen or collapsed hoses.
- Fuel system: leaks, water separator draining and fuel filter service intervals.
- Air intake and exhaust: air filter restriction indicator, charge air cooler leaks, exhaust leaks, and DPF and DEF system checks.
- Leaks and noises: oil, coolant, fuel and exhaust leaks, and what each one tells you.
B. Cab and Hood (about 5 questions)
- Safety items: seat belts, seats, mirrors, horn, wipers and washers, defroster and door latches.
- Gauges and warning lights: all instruments working, including the low-air warning.
- Hood and body: hood latches and tilt mechanism, steps and grab handles, and cab mounts.
- HVAC: cabin filter, blower operation and A/C performance.
C. Electrical/Electronics (about 10 questions)
- Batteries: state of charge (about 12.6 volts at rest for a fully charged 12-volt battery), load testing, clean and tight cables, and hold-downs.
- Starting and charging: cranking voltage, charging voltage at the batteries, and voltage drop on cables.
- Lighting: every exterior light and reflector, the trailer light cord, and the 7-way connector.
- Diagnostics: checking for active fault codes with a scan tool as part of the PMI.
D. Frame and Chassis (about 22 questions)
This is almost half the test. Know your measurements and what makes a truck unsafe to drive.
Air brakes
- Pushrod stroke checks at full application, and the adjustment limit for each brake chamber size.
- Air leak-down and build-up tests, governor cut-in and cut-out, and low-air warning operation.
- Drum and lining condition, air lines and chafing, and air dryer and reservoir draining.
Steering and suspension
- Steering wheel free play, tie rod ends, drag link, kingpins and steering gear mounting.
- Springs, U-bolts, shocks, air springs and ride height. Broken leaves and cracked hangers.
Tires, wheels and hubs
- Tread depth: at least 4/32 inch on steer tires and 2/32 inch on all others, under federal rules.
- Inflation, mismatched duals, sidewall damage and cracked wheels.
- Hub oil level and leaks, and wheel bearing end play.
Driveline, frame and fifth wheel
- U-joints, driveshaft slip joints and center bearings.
- Frame cracks, loose crossmembers and fifth-wheel locking jaw adjustment.
E. Road/Operational Test (about 3 questions)
- Brakes stop straight, the parking brake holds, and steering returns to center.
- Shifting, clutch, engine power and any noises or vibrations.
- Gauge readings at operating temperature, and checking for leaks after the drive.
Try a few practice questions
Question 1
During a PMI, a steer tire measures 3/32 inch of tread depth. What should the technician do?
- A. Pass it because it’s above 2/32 inch
- B. Record it and replace the tire before the truck goes back in service
- C. Rotate it to a drive position and pass it
- D. Increase tire pressure
Answer: B. Steer tires need at least 4/32 inch of tread under federal rules. Below that, the tire needs to be replaced.
Question 2
Technician A says coolant freeze protection should be checked with a refractometer. Technician B says SCA levels in conventional coolant can be checked with test strips. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both A and B
- D. Neither A nor B
Answer: C. Both are standard PMI checks.
Question 3
During a PMI, a 12-volt battery reads 12.2 volts after the truck has sat overnight. What does this mean?
- A. The battery is fully charged
- B. The battery is about half charged and needs charging and testing
- C. The alternator is overcharging
- D. The battery is ready for a load test
Answer: B. A fully charged 12-volt battery reads about 12.6 volts at rest. Charge it, then load test it before deciding whether to replace it.
A simple 4-week study plan
- Week 1, frame and chassis brakes: pushrod stroke limits, air system tests and foundation brake inspection.
- Week 2, the rest of frame and chassis: steering, suspension, tires, wheels, hubs and the fifth wheel.
- Week 3, engine and electrical: fluids, belts, cooling, batteries, charging and lighting.
- Week 4, cab, road test and practice: cab safety items, road test checks and timed practice tests.
Keep going with the ASE T-Series
After the T8, many techs move on to the T2 Diesel Engines test. Read our ASE T2 Diesel Engines study guide, then take a free practice test with instant explanations for every answer. T8 practice tests are coming soon.
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