By Michael Nielsen, Publisher | 15+ Years in Diesel Repair
Last Updated: November 2026
⏱ Estimated reading time: 38 minutes
ASE medium heavy truck practice questions show you what you still need to learn before you pay for a T-series test. ASE offers eight tests, T1 through T8, for technicians who work on Class 4 through 8 trucks, and each one asks 40 to 55 scored multiple-choice questions about a single system. This guide from Heavy Duty Journal gives you 49 original practice questions across all eight tests, each with an explained answer, plus ASE's published question counts, timing and format.
Costs and rules matter before you commit. As of November 2026, ASE's dates and fees page lists $62 per general test plus a $34 registration fee per order, and the Master Medium-Heavy Truck Technician title requires T2 through T8. The questions below are written by Heavy Duty Journal. They are not actual ASE questions, so use them to find weak spots rather than to predict your exam.
Key Takeaways
- ✓Eight tests, 40 to 55 scored questions each. T1 through T8 cover gasoline engines, diesel engines, drivetrain, brakes, suspension and steering, electrical, HVAC and preventive maintenance inspection.
- ✓Expect Technician A and Technician B items. ASE tests use four choices, many Technician A/B statements and flagged EXCEPT questions, and ASE does not publish a passing score.
- ✓Study by weight. Air brakes are 32 of the 50 scored questions on T4, and the fuel system is 16 of 55 on T2, so those topics deserve the most time.
- ✓Master status needs seven tests. The Master Medium-Heavy Truck Technician title requires T2 through T8, and T1 is not part of it.
In This Guide
- ASE Medium Heavy Truck Practice Questions: Tests at a Glance
- How the ASE T-Series Tests Work
- How to Use These Practice Questions
- T1 Gasoline Engines Practice Questions
- T2 Diesel Engines Practice Questions
- T3 Drivetrain Practice Questions
- T4 Brakes Practice Questions
- T5 Suspension and Steering Practice Questions
- T6 Electrical/Electronic Systems Practice Questions
- T7 Heating, Ventilation and A/C Practice Questions
- T8 Preventive Maintenance Inspection Practice Questions
- Test-Taking Strategy and Test Day Plan
- Registration, Experience and Recertification
- Frequently Asked Questions
- The Bottom Line
ASE Medium Heavy Truck Practice Questions: Tests at a Glance
ASE medium heavy truck practice questions prepare you for the T-series tests, which Automotive Service Excellence (ASE) offers for technicians who diagnose and repair Class 4 through 8 trucks. The ASE T-series page lists the scored question count and time limit for every test, and recertification tests are shorter than the first-time versions.
| Test | Subject | Scored questions / time | Recert questions / time |
|---|---|---|---|
| T1 | Gasoline Engines | 50 / 75 min | 25 / 30 min |
| T2 | Diesel Engines | 55 / 90 min | 28 / 45 min |
| T3 | Drivetrain | 40 / 60 min | 20 / 30 min |
| T4 | Brakes | 50 / 75 min | 25 / 30 min |
| T5 | Suspension and Steering | 50 / 75 min | 25 / 30 min |
| T6 | Electrical/Electronic Systems | 50 / 90 min | 25 / 45 min |
| T7 | Heating, Ventilation and A/C (HVAC) | 40 / 60 min | 20 / 30 min |
| T8 | Preventive Maintenance Inspection (PMI) | 50 / 75 min | 25 / 30 min |
Each first-time test also carries 10 unscored research questions, so the number you see is higher than the scored count. Recertification tests (T1R through T8R) have none. A Master Medium-Heavy Truck Technician has passed T2 through T8, and ASE notes that T1 is not required for the Master title.
If you need the full registration process, cost breakdown and experience rules, Heavy Duty Journal covers them in ASE Certification for Heavy Duty Trucks: Tests, Fees, Rules. This page focuses on what that guide does not: practice questions, answer reasoning and how to study each test.
How the ASE T-Series Tests Work
The ASE T-series tests are computer-based multiple-choice exams with four answer choices (A through D) per question. According to the official ASE study guide for medium and heavy trucks, many questions use a Technician A / Technician B format, some are marked EXCEPT, and some include a figure or schematic.
| Question style | How it reads | How to answer |
|---|---|---|
| Technician A / Technician B | Two technicians each make a statement; choose A only, B only, both or neither | Judge each statement as true or false on its own, then pick the matching choice |
| EXCEPT | Three choices are correct and one is not | Find the one false or non-applicable choice |
| Direct question | One question, one best answer | Eliminate the wrong choices, then confirm the last one |
| Figure or schematic | A diagram or reading accompanies the question | Study the figure before you read the choices |
The study guide lists the content areas for each test and how many scored questions come from each area. The counts in the test sections below come from that guide, and every set of ASE medium heavy truck practice questions on this page is tied to those content areas. ASE does not publish a passing score on the T-series page or in the study guide, so do not trust any site that quotes one for these tests.
Certification needs more than a passing test result. ASE requires full-time hands-on work experience, or a combination of formal training and experience, and the certificate is delayed until the experience is approved. The study guide lists 2 years of work experience for this series, with vocational training able to substitute in part. ASE's work experience page says only employed experience counts, not classroom time, that accepted documentation includes transcripts and completion certificates, and that ASE can deny certification for false information.
Plan your timeline around the experience requirement as well as the test, and start your ASE medium heavy truck practice questions early. Technicians who already work in a shop can usually document their experience as they go, while students should keep transcripts and certificates from training programs. Heavy Duty Journal's diesel technician career progression guide shows where ASE credentials fit in a longer career.
How to Use These Practice Questions
ASE medium heavy truck practice questions work best when you treat them as a diagnostic tool. Take each test section cold, write down your answer before you open the explanation, and then read the explanation even when you were right. HDJ wrote these 49 questions to match the style and skills ASE describes, but they are original and do not come from ASE exams or any other publisher's question bank.
| Step | What to do | Why it helps |
|---|---|---|
| 1. Answer cold | Answer all questions in a section before opening any explanation | Shows what you actually know, not what you recognize |
| 2. Read every explanation | Read the reasoning even for correct answers | Confirms you got it right for the right reason |
| 3. Map misses to content areas | Match each miss to a row in the content-area table | Points your study time at the heaviest weak spots |
| 4. Review the service information | Study the system in your shop manual or training materials | Questions are built on how the system works |
| 5. Retest after a week | Redo missed questions after studying | Checks that the fix stuck |
ASE also runs an official practice program. The official ASE practice test program offers online quizzes with explanations, and for trucks it covers T2 (28 questions), T4 (25), T6 (25) and T8 (25). ASE says those practice tests are about half the length of the real ones, and its vouchers must be used within 60 days of redemption and are non-refundable. Heavy Duty Journal's 90-day ASE T-series study guide lays out a week-by-week plan that pairs well with these questions.
In Heavy Duty Journal's field experience across 15+ years of diesel repair, the technicians who struggle on ASE tests are rarely missing facts. They tend to misread the question, especially EXCEPT items and Technician A/B statements. Practice reading slowly and judging each statement separately.
T1 Gasoline Engines Practice Questions
T1 Gasoline Engines tests diagnosis and repair of gasoline engines in medium and heavy trucks, so it is the one T-series test aimed at gas-powered Class 4 through 8 vehicles. These ASE medium heavy truck practice questions focus on the largest T1 areas, general engine diagnosis and computerized controls, which together make up 22 of the 50 scored questions.
| Content area | Scored questions |
|---|---|
| General Engine Diagnosis | 14 |
| Cylinder Head and Valve Train | 4 |
| Engine Block | 4 |
| Lubrication and Cooling Systems | 3 |
| Ignition System | 6 |
| Fuel, Air Induction and Exhaust Systems | 6 |
| Emissions Control Systems | 5 |
| Computerized Engine Controls | 8 |
Study focus: spend most of your study time on diagnosis, and weight your ASE medium heavy truck practice questions the same way. Practice reading fuel trims, interpreting compression and leakage results and tracing a symptom to a system. T1 is optional for the Master title, so skip it only if gas trucks are not part of your work.
T1 Practice Question 1
Technician A says a vacuum leak at the intake manifold makes the air-fuel mixture richer. Technician B says a lean mixture can cause a misfire. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: B. Air that enters through a vacuum leak bypasses the airflow measurement, so the engine receives more air than the computer accounts for and the mixture goes lean, not rich. A lean mixture can burn too slowly or fail to ignite, which produces a misfire. Only Technician B is correct.
T1 Practice Question 2
A gasoline engine has one cylinder with a low compression reading. After a small amount of engine oil is added to that cylinder, the reading rises sharply. Which condition is the most likely cause?
- A. A burned exhaust valve
- B. A blown head gasket between two cylinders
- C. A worn camshaft lobe
- D. Worn piston rings or cylinder wall
Show answer and explanation
Answer: D. Oil temporarily seals the gap between the rings and the cylinder wall, so a large jump in the reading points to ring or bore wear. A burned valve or a head gasket leak would not be sealed by oil, so the reading would stay low. A gasket leak between cylinders would also show up as two low cylinders.
T1 Practice Question 3
A truck with a gasoline engine shows short-term fuel trim of +20 percent at idle that drops to nearly 0 percent at 2,500 rpm. No codes are stored. Which cause is most likely?
- A. A vacuum leak downstream of the airflow measurement
- B. A restricted fuel filter
- C. A leaking fuel injector
- D. An engine coolant temperature sensor that reads colder than actual
Show answer and explanation
Answer: A. A fixed unmetered air leak is a large share of total airflow at idle and a small share at higher airflow, so the computer adds fuel at idle and the trim fades as rpm rises. A restricted filter would get worse with demand. A leaking injector or a falsely cold temperature reading makes the engine run rich, which produces negative trim.
T1 Practice Question 4
A stuck-open thermostat can cause all of the following EXCEPT:
- A. Longer engine warm-up time
- B. Reduced cab heater output
- C. Increased fuel consumption
- D. Engine overheating at idle
Show answer and explanation
Answer: D. A thermostat stuck open lets coolant flow to the radiator all the time, so the engine warms slowly, the heater produces less heat, and fuel use can rise because the computer keeps the mixture enriched longer. Overheating is the symptom of a thermostat stuck closed, not open.
T1 Practice Question 5
Technician A says a positive crankcase ventilation (PCV) valve stuck open adds unmetered air and can lean out the idle mixture. Technician B says a plugged PCV system lowers crankcase pressure. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: A. A stuck-open PCV valve pulls extra air into the intake after the airflow measurement, which can lean out the idle mixture. A plugged PCV system does the opposite of what Technician B says: crankcase pressure builds, which can push oil past seals and into the intake. Only Technician A is correct.
T1 Practice Question 6
After ruling out misfires and exhaust leaks, a technician sees that the downstream oxygen sensor on a gasoline truck switches rapidly, almost like the upstream sensor, and a catalyst efficiency code is set. What is the most likely cause?
- A. The catalyst's oxygen storage capacity has dropped
- B. The fuel pressure regulator is leaking
- C. The EVAP purge valve is stuck closed
- D. The thermostat is stuck open
Show answer and explanation
Answer: A. A healthy catalytic converter stores oxygen, so the downstream sensor signal is steadier and slower than the upstream signal. When the downstream signal mirrors the upstream one, the converter is no longer storing oxygen and is below its efficiency threshold. Misfires and exhaust leaks can set the same code, which is why they are checked first.
T2 Diesel Engines Practice Questions
T2 Diesel Engines tests diagnosis and repair of diesel engines, and it is the largest of the eight tests with 55 scored questions in 90 minutes. The fuel system is the heaviest area at 16 of 55 questions, or 29 percent, followed by general engine diagnosis at 11. Use these ASE medium heavy truck practice questions to check both.
| Content area | Scored questions |
|---|---|
| General Engine Diagnosis | 11 |
| Cylinder Head and Valve Train | 4 |
| Engine Block | 5 |
| Lubrication and Cooling Systems | 6 |
| Air Induction and Exhaust Systems | 6 |
| Fuel System | 16 |
| Starting and Charging Systems | 4 |
| Engine Brakes | 3 |
Study focus: learn the symptom-to-cause chain for smoke color, boost and fuel delivery, and review the service procedures for your engines. T2 is required for the Master title.
T2 Practice Question 1
A turbocharged diesel makes heavy black smoke under load, and boost pressure reads lower than specification. Which cause is most likely?
- A. Coolant entering the combustion chamber
- B. Worn valve guides
- C. A low engine oil level
- D. A leaking charge air cooler hose or boot
Show answer and explanation
Answer: D. Black smoke is unburned fuel, which means the engine is running rich: too little air for the fuel delivered. A boost leak lowers the air entering the cylinders. Coolant in the chamber causes white smoke, and worn valve guides let oil into the cylinders, which causes blue-gray smoke.
T2 Practice Question 2
Technician A says white smoke that continues after warm-up, together with coolant loss, can mean coolant is entering a cylinder. Technician B says combustion gases in the cooling system can pressurize it and push coolant out of the overflow. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: C. A failed head gasket, a cracked head or a damaged liner seal can let coolant into a cylinder and let combustion gas into the coolant. Persistent white smoke with coolant loss and a pressurized cooling system with no external leak are both classic signs. A combustion leak test confirms the diagnosis. Both technicians are correct.
T2 Practice Question 3
Technician A says a piece of cardboard or paper should be used to find a high-pressure diesel fuel leak. Technician B says it is safe to feel for a high-pressure fuel leak with a gloved hand if the engine is only idling. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: A. Fuel escaping a high-pressure system can penetrate skin and cause a serious injury even from a pinhole leak, so a technician looks for the leak with cardboard or paper and wears eye or face protection. A glove does not protect against injection, and idling pressure can still be high on a common-rail system. Follow the manufacturer's procedure for relieving pressure. Only Technician A is correct.
T2 Practice Question 4
A compression-release engine brake slows the truck by:
- A. Injecting extra fuel during the compression stroke
- B. Closing the intake valves for the whole cycle
- C. Opening the exhaust valves near the top of the compression stroke so the compressed air is released
- D. Applying friction to the flywheel
Show answer and explanation
Answer: C. During braking, the engine acts as an air compressor, and the piston does work compressing the air. Opening the exhaust valve near the top of the stroke releases that air so the energy absorbed during compression is not returned to the crankshaft on the power stroke. The engine therefore acts as a power-absorbing air compressor, which retards the vehicle.
T2 Practice Question 5
Technician A says a voltage drop test on the starter circuit is performed with the circuit de-energized. Technician B says corroded battery terminals cannot cause slow cranking if the battery passes a load test. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: D. A voltage drop test must be done with current flowing, which on a starter circuit means while cranking, because resistance only shows up under load. Corroded terminals add resistance and reduce the voltage and current that reach the starter even when the battery is good. Neither statement is correct.
T2 Practice Question 6
Technician A says excessive blow-by is usually caused by a plugged air filter. Technician B says a restricted crankcase breather can raise crankcase pressure and cause oil leaks at seals. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: B. Excessive blow-by is combustion gas leaking past the rings, so it usually points to worn rings or liners rather than the air filter. A restricted breather keeps crankcase pressure from venting, and the pressure can push oil past seals and gaskets. Only Technician B is correct.
T3 Drivetrain Practice Questions
T3 Drivetrain tests diagnosis and repair of clutches, transmissions, driveshafts and drive axles in medium and heavy trucks. With 40 scored questions in 60 minutes, it is among the shortest tests, and the transmission area is the largest at 13 questions. These ASE medium heavy truck practice questions cover all four areas.
| Content area | Scored questions |
|---|---|
| Clutch | 11 |
| Transmission | 13 |
| Driveshaft and Universal Joint | 7 |
| Drive Axle | 9 |
Study focus: know how free play, release travel and the clutch brake affect each other, and learn the inspection signs that separate normal axle wear from damage. T3 is required for the Master title.
T3 Practice Question 1
Technician A says too little clutch pedal free play can cause the clutch to slip. Technician B says too much free play can prevent the clutch from releasing fully. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: C. With no free play, the release bearing can keep pressure on the clutch, and the disc slips and overheats. With too much free play, the pedal runs out of travel before the clutch fully releases, which causes dragging, gear clash and hard shifting. Both technicians are correct.
T3 Practice Question 2
On a heavy truck with a manual transmission, a clutch brake is used to:
- A. Stop input shaft rotation so a gear can be engaged from a standstill when the pedal is fully pressed
- B. Slow the engine during a downshift
- C. Hold the truck on a grade
- D. Prevent clutch slip under heavy load
Show answer and explanation
Answer: A. The clutch brake is a friction device on the input shaft. When the pedal is pushed to the floor, it stops the input shaft from spinning so first or reverse can be engaged with the truck stopped. It is not used while moving, and it does not hold the truck or affect clutch slip.
T3 Practice Question 3
Technician A says driveshaft yokes installed out of phase can cause a vibration. Technician B says the universal joint operating angles at each end of a shaft should differ as much as possible to cancel vibration. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: A. When the yokes are not in phase, the speed fluctuations from the two joints add instead of cancelling, and the shaft vibrates. To cancel the fluctuations, the operating angles at each end should be nearly equal, not as different as possible. Only Technician A is correct.
T3 Practice Question 4
Technician A says an inter-axle differential lock can be engaged safely while the drive wheels are already spinning freely. Technician B says the inter-axle lock should be disengaged for normal driving on dry pavement. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: B. Manufacturers warn against engaging the lock while wheels are slipping because the speed difference can damage the driveline. The lock is meant to be engaged before traction is lost and released once traction returns, and it should be off for normal dry-road driving. Only Technician B is correct.
T3 Practice Question 5
While inspecting a drive axle, a technician finds the following on the magnetic drain plug. Which finding calls for further teardown and inspection?
- A. A thin gray paste of fine metal particles
- B. A light fuzz of metal powder
- C. Chips and slivers of metal
- D. Dark gear oil that is thick but clean
Show answer and explanation
Answer: C. Fine paste and powder on the magnet are signs of normal wear in gears and bearings. Chips and slivers indicate that a gear tooth, bearing or other part is breaking up, and the axle needs further inspection before it fails. Dark oil alone is not a sign of damage.
T3 Practice Question 6
Technician A says dark automatic transmission fluid with a burnt smell can indicate overheating. Technician B says milky pink fluid can indicate coolant contamination from a failed internal cooler. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: C. Burnt-smelling dark fluid points to heat or friction material wear. Milky pink fluid is a classic sign that coolant is entering the transmission, often through a failed cooler inside the radiator. Both technicians are correct, and coolant contamination means the unit and the cooling system both need attention.
T4 Brakes Practice Questions
T4 Brakes tests diagnosis and repair of air, hydraulic and antilock brake systems on medium and heavy trucks. Air brakes dominate the test, so these ASE medium heavy truck practice questions lean toward air brake supply, foundation components and parking brakes.
| Content area | Scored questions |
|---|---|
| Air Brakes (total) | 32 |
| Air supply and service brakes | 15 |
| Foundation brakes and wheel hubs | 13 |
| Parking brakes | 4 |
| Hydraulic Brakes | 11 |
| ABS, ATC, ESC and collision warning systems | 7 |
64%
Share of the 50 scored T4 questions that cover air brakes (32 of 50). Source: ASE study guide for medium and heavy truck tests.
Study focus: master the air supply path from compressor to governor, dryer and tanks, then the foundation brake components. T4 is required for the Master title.
T4 Practice Question 1
Technician A says the governor controls when the air compressor loads and unloads. Technician B says the governor cut-in pressure is higher than the cut-out pressure. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: A. The governor senses system air pressure and signals the compressor to stop building pressure at cut-out and to resume at cut-in. Cut-in is the lower pressure, which gives the system a gap so the compressor does not cycle constantly. Only Technician A is correct.
T4 Practice Question 2
Under 49 CFR 393.50, the reservoir system must have enough reserve capacity that, after a full service brake application with the engine stopped, the remaining pressure is at least what percentage of the pressure before the application?
- A. 50 percent
- B. 60 percent
- C. 70 percent
- D. 80 percent
Show answer and explanation
Answer: C. The federal reservoir rule sets the reserve capacity so a full service brake application with the engine stopped leaves at least 70 percent of the pre-application pressure. The same section requires check valves protecting the service reservoir system and a manually operable condensate drain on each reservoir.
T4 Practice Question 3
Technician A says automatic slack adjusters should be backed off and adjusted by hand at every service to keep the stroke correct. Technician B says excessive pushrod stroke on a vehicle with automatic slack adjusters points to a problem that needs to be diagnosed. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: B. Automatic slack adjusters are designed to keep the stroke in range without manual adjustment, so hand adjusting them hides the cause. If stroke is excessive, the technician looks for worn components, a damaged adjuster, a bent bracket or incorrect installation. Only Technician B is correct.
T4 Practice Question 4
A brake drum measures larger than the maximum diameter marked on it. What should the technician do?
- A. Replace the drum
- B. Machine the drum and reuse it with new lining
- C. Install thicker lining to make up the difference
- D. Balance the drum and reuse it
Show answer and explanation
Answer: A. The marked discard diameter is the limit for wear and machining. A drum beyond that limit has less metal to absorb and shed heat and can crack or fade, so it must be replaced. New lining does not compensate for a worn-out drum.
T4 Practice Question 5
Technician A says an ABS malfunction disables the conventional service brakes. Technician B says the ABS warning lamp normally lights briefly at key-on and then goes out. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: B. The ABS lamp comes on during a bulb check at key-on and goes out when the system self-test passes. When an ABS fault occurs, the antilock function is disabled, but the conventional service brakes keep working. Only Technician B is correct.
T4 Practice Question 6
Technician A says a conventional DOT 3 or DOT 4 hydraulic brake system may be flushed with mineral oil. Technician B says brake fluid is not affected by moisture. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: D. Petroleum-based fluids swell the rubber seals in a conventional brake system and can cause failure. Brake fluid absorbs moisture over time, which lowers its boiling point and promotes corrosion. Neither statement is correct.
⚠️ Safety Warning
A spring brake chamber holds a power spring under very high compression. Never remove the clamp ring or open a spring brake chamber, and never cut, drill or strike it. Release the spring only with the manufacturer's caging procedure, and replace a damaged chamber as a complete assembly. Treat a pressurized air line the same way: release air before disconnecting it.
T4 Practice Question 7
Technician A says a spring brake is applied by spring force when air is released from the chamber. Technician B says air pressure compresses the power spring and holds the parking brake released. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: C. Spring brakes are fail-safe: air pressure in the chamber holds the spring compressed and the brake released, and when air is exhausted the spring applies the brake. That is why a severe air loss can lock the brakes on its own. Both technicians are correct.
T5 Suspension and Steering Practice Questions
T5 Suspension and Steering tests diagnosis and repair of steering systems, suspension, frames, fifth wheels, alignment, wheels, tires and hubs. The suspension, frame and fifth wheel area is the largest at 16 of 50 questions, and alignment follows with 13. These ASE medium heavy truck practice questions include two federal rules the test builds on.
| Content area | Scored questions |
|---|---|
| Steering Systems | 12 |
| Suspension, Frame and Fifth Wheel | 16 |
| Wheel Alignment | 13 |
| Wheels, Tires and Hubs | 9 |
Study focus: connect tire wear patterns to alignment and suspension faults, and know the federal tread depth and steering lash limits. T5 is required for the Master title.
T5 Practice Question 1
Technician A says under 49 CFR 393.75, a steering-axle tire with 3/32 inch of tread in a major groove does not meet the federal minimum. Technician B says a drive tire with 3/32 inch of tread in a major groove meets the federal minimum. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: C. The federal tire rule requires at least 4/32 inch of tread on the front (steering) tires of a truck or truck-tractor and at least 2/32 inch on all other tires, measured in a major tread groove. A steer tire at 3/32 inch fails, and a drive tire at 3/32 inch passes. Both technicians are correct.
T5 Practice Question 2
A truck's tires show faster wear in the center of the tread than at the shoulders. What is the most likely cause?
- A. Underinflation
- B. Excessive toe
- C. A worn shock absorber
- D. Overinflation
Show answer and explanation
Answer: D. Too much air pressure makes the tread crown bulge, so the center carries more load and wears first. Underinflation wears both shoulders, bad toe produces feathered wear, and a worn shock absorber usually produces cupping.
T5 Practice Question 3
Under 49 CFR 393.209, what is the maximum allowed steering wheel lash for a truck with power steering and an 18-inch steering wheel?
- A. 4 3/4 inches
- B. 2 1/4 inches
- C. 5 1/4 inches
- D. 2 inches
Show answer and explanation
Answer: A. The federal steering rule table allows 4 3/4 inches (121 mm) of lash on an 18-inch wheel with power steering. A manual steering system with the same wheel is limited to 2 1/4 inches. For wheel diameters not listed in the table, the limit is 14 degrees of rotation for manual steering and 30 degrees for power steering.
T5 Practice Question 4
Technician A says after coupling a tractor to a trailer, a tug test against the trailer brakes helps confirm that the fifth wheel is locked. Technician B says a visual check of the locking jaws is unnecessary if the tug test passes. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: A. A gentle pull forward against the set trailer brakes confirms the kingpin is held. A tug test does not replace a visual check, because the technician should also confirm the jaws closed around the kingpin and the release handle is in the locked position. Only Technician A is correct.
T5 Practice Question 5
Technician A says tire conicity (radial pull) cannot make a truck pull to one side. Technician B says unequal tire pressure from side to side can make a truck pull. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: B. A tire with a conical construction acts like a tapered roller and can steer the truck, and unequal pressure creates unequal rolling resistance and a pull. Alignment is not the only cause of a pull, so tires should be checked first. Only Technician B is correct.
T5 Practice Question 6
Technician A says wheel fasteners should be tightened in a crisscross sequence and in stages. Technician B says wheel fastener torque should be rechecked after a short trip, following the manufacturer's recommendation. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: C. A star pattern in stages seats the wheel evenly on the hub, and clamp load can settle after the first miles, which is why a recheck is recommended. Loose wheels are a serious hazard. Both technicians are correct.
T6 Electrical/Electronic Systems Practice Questions
T6 Electrical/Electronic Systems tests diagnosis and repair of batteries, starting and charging systems, lighting and related electrical systems on medium and heavy trucks. General diagnosis is the largest area at 14 of 50 questions, and the 90-minute time limit is the longest on the T-series list. These ASE medium heavy truck practice questions center on circuit logic.
| Content area | Scored questions |
|---|---|
| General Electrical/Electronic System Diagnosis | 14 |
| Battery and Starting Systems | 11 |
| Charging Systems | 7 |
| Lighting Systems | 6 |
| Related Systems | 12 |
Study focus: practice Ohm's law, voltage drop testing and reading wiring diagrams until the steps are automatic. For the data network side, read Heavy Duty Journal's J1939 explained guide for fleet technicians. T6 is required for the Master title.
T6 Practice Question 1
A lamp with 3 ohms of resistance is connected to a 12-volt supply. How much current flows through the circuit?
- A. 0.25 amp
- B. 9 amps
- C. 36 amps
- D. 4 amps
Show answer and explanation
Answer: D. Ohm's law says current equals voltage divided by resistance, so 12 volts divided by 3 ohms gives 4 amps. Multiplying instead of dividing is the common error and produces the 36 amp choice.
T6 Practice Question 2
Two 12-volt batteries rated at 700 cold cranking amps each are connected in parallel. What does the pair deliver?
- A. 12 volts and 1,400 cold cranking amps
- B. 24 volts and 700 cold cranking amps
- C. 24 volts and 1,400 cold cranking amps
- D. 12 volts and 700 cold cranking amps
Show answer and explanation
Answer: A. Parallel connections add capacity and keep the same voltage, so the pair delivers 12 volts with the cranking amps added together. A series connection adds voltage and keeps the same amp rating, which is how 24-volt systems are built.
T6 Practice Question 3
A voltage drop of 1.2 volts is measured across a closed switch in a 12-volt lighting circuit while the lights are on. What does this indicate?
- A. An open ground circuit
- B. A weak battery
- C. A blown fuse
- D. Excessive resistance in the switch or its connections
Show answer and explanation
Answer: D. A closed switch should drop only a fraction of a volt. A drop of 1.2 volts means too much resistance in the contacts or connections, which steals voltage from the lamp and causes dim lights. A weak battery would reduce the supply voltage, not create a drop across the switch.
T6 Practice Question 4
Technician A says a charging system regulator controls output by varying the current in the alternator field. Technician B says with the engine running, a properly charging 12-volt system shows lower voltage than the battery's resting voltage. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: A. The voltage regulator changes field current to hold system voltage in range. A properly charging system must show higher voltage than the battery's resting voltage, or the alternator would not be able to push current into the battery. Only Technician A is correct.
T6 Practice Question 5
With the power off, what resistance should a technician expect between CAN high and CAN low at the diagnostic connector on a healthy J1939 network?
- A. About 0 ohms
- B. About 120 ohms
- C. About 60 ohms
- D. Infinite resistance
Show answer and explanation
Answer: C. A J1939 network has a 120-ohm terminating resistor at each end. Measured across the pair, the two resistors are in parallel and read about 60 ohms. A reading near 120 ohms suggests one terminator is missing or a wire is open, and 0 ohms suggests a short.
T6 Practice Question 6
Technician A says welding on a frame with electronic modules connected is safe if the welder ground clamp is attached to the battery negative post. Technician B says disconnecting the battery cables and the module harness connectors helps protect electronic modules during arc welding. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: B. Welding current can travel through the vehicle's wiring and damage modules, and a ground clamp on a battery post invites that path. The recommended practice is to follow the manufacturer's precautions: disconnect the battery and the module connectors, and place the ground clamp close to the weld. Only Technician B is correct.
T7 Heating, Ventilation and A/C Practice Questions
T7 Heating, Ventilation and A/C tests diagnosis and repair of cab climate systems on medium and heavy trucks. The A/C system is the heart of the test at 20 of 40 scored questions. These ASE medium heavy truck practice questions cover refrigerant flow, gauge diagnosis, heating, evacuation and condenser airflow.
| Content area | Scored questions |
|---|---|
| HVAC Diagnosis | 6 |
| A/C System | 20 |
| Heating and Cooling | 6 |
| Controls | 8 |
Study focus: learn what each gauge pattern means and what each component does in the refrigerant cycle. ASE says its HVAC certification does not provide the credentials needed for EPA Section 609, so refrigerant handling certification is a separate step. T7 is required for the Master title.
T7 Practice Question 1
Technician A says a receiver-drier is used in systems with a thermostatic expansion valve. Technician B says an accumulator is installed on the high side in systems with an expansion valve. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: A. A receiver-drier holds liquid refrigerant and moisture-absorbing desiccant in expansion-valve systems. An accumulator is used in orifice-tube systems and sits on the low side between the evaporator and the compressor. Only Technician A is correct.
T7 Practice Question 2
Technician A says passing ASE T7 satisfies the EPA Section 609 requirement for handling refrigerant. Technician B says a separate approved Section 609 program is needed to meet that requirement. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: B. ASE states that its HVAC certifications do not provide the credentials needed for EPA Section 609, and it points technicians to a separate refrigerant recovery and recycling review program. Only Technician B is correct.
T7 Practice Question 3
On a cab A/C system, the low-side gauge reads higher than normal and the high-side gauge reads lower than normal. What is the most likely cause?
- A. An inefficient compressor
- B. A restricted orifice tube
- C. An overcharge of refrigerant
- D. A blocked condenser
Show answer and explanation
Answer: A. A compressor that cannot build pressure lets refrigerant leak from the high side back to the low side, so the low side rises and the high side stays low. A restriction lowers the low-side reading, and an overcharge or blocked condenser raises the high side.
T7 Practice Question 4
A cab heater blows little warm air. The heater core inlet hose is hot, but the outlet hose is cool. What is the most likely cause?
- A. A thermostat stuck open
- B. A restricted heater core
- C. A blend door stuck on cold
- D. A weak blower motor
Show answer and explanation
Answer: B. Hot coolant is entering the core but is not flowing through it, which points to a restriction inside the heater core. A blend door stuck on cold or a weak blower affects the air, not the hose temperatures, and a stuck-open thermostat lowers coolant temperature on both hoses.
T7 Practice Question 5
Technician A says pulling a vacuum lowers the boiling point of moisture in the system so the moisture can be removed. Technician B says the system should hold a vacuum with the pump off for a period of time to confirm there are no leaks. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: C. Evacuation removes air and moisture because water boils at a lower temperature under vacuum. A vacuum hold test checks for leaks before the system is charged. Both technicians are correct.
T7 Practice Question 6
A truck's A/C produces high head pressure at idle, but the pressure is normal at highway speed. What is the most likely cause?
- A. Low refrigerant charge
- B. A restricted orifice tube
- C. A worn compressor
- D. Inadequate airflow through the condenser at low speed
Show answer and explanation
Answer: D. At idle the condenser depends on the cooling fan for airflow, and at highway speed ram air supplies it. High pressure only at idle points to a fan or fan clutch that is not moving enough air, or a blocked condenser. Low charge or a worn compressor would lower pressure, not raise it.
T8 Preventive Maintenance Inspection Practice Questions
T8 Preventive Maintenance Inspection (PMI) tests whether a technician can inspect a truck systematically, find developing problems and know when a component fails. Frame and chassis is the largest area at 22 of 50 scored questions. These ASE medium heavy truck practice questions include the federal inspection rules that T8 builds on.
| Content area | Scored questions |
|---|---|
| Engine | 10 |
| Cab and Hood | 5 |
| Electrical/Electronics | 10 |
| Frame and Chassis | 22 |
| Road/Operational Test | 3 |
Study focus: practice working through a full inspection in order and know the federal inspection basics. T8 is required for the Master title, and it is one of the four truck tests with an official ASE practice test.
T8 Practice Question 1
Under 49 CFR 396.17, how often must a commercial motor vehicle receive a periodic inspection?
- A. At least every 6 months
- B. At least every 12 months
- C. At least every 24 months
- D. At least every 90 days
Show answer and explanation
Answer: B. The federal periodic inspection rule requires an inspection at least once every 12 months against the inspection items in appendix A of part 396. A motor carrier may use its own inspector or a commercial agent, and documentation of the inspection, a report or a sticker, must be on the vehicle.
T8 Practice Question 2
Technician A says each air reservoir must have a manually operable condensate drain. Technician B says oil found when draining the tanks can point to compressor oil carryover. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: C. Federal brake rules require a manual drain on each air reservoir, and the drains are how a technician checks what is collecting in the tanks. Water is common, but oil in the tanks is not normal and suggests the compressor is passing oil. Both technicians are correct.
T8 Practice Question 3
Technician A says coolant color alone reliably identifies the coolant type and its condition. Technician B says a refractometer can be used to check coolant freeze protection. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: B. Color varies by manufacturer and does not tell you the type or the inhibitor level, so the coolant should be tested and matched to the engine manufacturer's specification. A refractometer measures the freeze point reliably. Only Technician B is correct.
T8 Practice Question 4
Technician A says the manufacturer's frame repair guidance should be checked before a frame rail is drilled or welded. Technician B says a hole drilled in the top or bottom flange of a frame rail is always acceptable. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: A. Many frame rails are heat-treated steel, and drilling or welding in the wrong place can create stress risers that crack. Manufacturers publish where holes may be drilled and which repairs are allowed. Only Technician A is correct.
T8 Practice Question 5
Before starting a road test, what should a technician do?
- A. Wait until highway speed to check the brakes
- B. Disable the ABS to simplify the test
- C. Test with the air system only partly charged
- D. Check the brakes at low speed in the yard before entering traffic
Show answer and explanation
Answer: D. A low-speed brake check in the lot confirms that the truck can stop before it enters traffic, and the air system should be fully charged so the test reflects normal operation. The road/operational test area is only 3 of 50 scored questions, but the check itself is basic safety.
T8 Practice Question 6
Technician A says a visual check is enough to judge tire inflation. Technician B says tire pressure is best checked and adjusted right after a long highway run, while the tires are hot. Who is right?
- A. Technician A only
- B. Technician B only
- C. Both Technician A and Technician B
- D. Neither Technician A nor Technician B
Show answer and explanation
Answer: D. A tire can look normal and still be well below its correct pressure, so a calibrated gauge is needed. Pressure should be checked cold, because hot tires read higher and bleeding them down to the cold specification leaves them underinflated. Neither statement is correct.
Test-Taking Strategy and Test Day Plan
The best strategy for ASE medium heavy truck practice questions, and for the real tests, is to read each question completely, judge each statement on its own and pace yourself against the clock. Each first-time test includes 10 unscored research questions, so the number of questions you answer is higher than the scored count. The table divides the stated time by the total questions you will see, which gives a rough pace per question and assumes the time limit covers all of them.
| Test | Questions you see | Time | Rough pace per question |
|---|---|---|---|
| T1 | 60 | 75 min | About 1.25 min |
| T2 | 65 | 90 min | About 1.4 min |
| T3 | 50 | 60 min | About 1.2 min |
| T4 | 60 | 75 min | About 1.25 min |
| T5 | 60 | 75 min | About 1.25 min |
| T6 | 60 | 90 min | About 1.5 min |
| T7 | 50 | 60 min | About 1.2 min |
| T8 | 60 | 75 min | About 1.25 min |
Use a simple routine on every question. These habits are HDJ recommendations drawn from the question styles in the ASE study guide, not ASE rules.
Question-by-Question Routine
- Read the whole stem: look for EXCEPT, the system named and any figure before you read the choices
- Judge A and B separately: decide true or false for each technician before you look at the answer choices
- Eliminate first: remove choices that contradict how the system works, then compare the rest
- Skip and return: mark a slow question and come back, so one hard item does not cost you five easy ones
- Check units and symptoms: confirm whether the question asks for a cause, a test or a repair
Logistics matter too. As of November 2026, ASE says you can test at a Prometric center or, if eligible, online with remote testing, and that purchased tests must be scheduled and taken within 90 days of purchase. ASE does not allow appointment changes within three days of the test, so confirm your date before you pay. Working back from your test date with a written study plan keeps the schedule realistic.
Registration, Experience and Recertification
Registering for the ASE T-series tests costs $62 per general test plus a $34 registration fee per order, as of November 2026. Recertification tests are $62 each with a $186 cap on test fees, so the most a recertification order can cost is $220 including registration. ASE lists four registration windows for 2026, and the current one runs October 10 through December 31.
| Item | ASE detail | Source note |
|---|---|---|
| General test fee | $62 per test | ASE dates and fees page |
| Registration fee | $34 per order | ASE dates and fees page |
| Recertification fee | $62 per test, $186 cap on tests | Maximum $220 with registration |
| Time to test | Schedule and take within 90 days of purchase | Refund for untaken tests cancelled within 90 days |
| Certification cycle | Retest every five years | Recertification requires a passing initial test |
| Early recertification | No credit for remaining time | New expiration is five years from the recert date |
Master status is the usual goal for a technician who passes the full set. The Master Medium-Heavy Truck Technician title requires T2 through T8, and each test must be kept current through recertification. Heavy Duty Journal explains the timeline and cost in ASE Recertification Requirements: Complete Guide for Diesel Technicians, and the broader test lineup in ASE Certification for Diesel Technicians: Tests and Costs.
Plan the order of tests, and the order you study the ASE medium heavy truck practice questions, around your daily work. Technicians who work on engines every day often start with T2 and T6, while brake and chassis specialists may begin with T4 and T5. Each pass is an individual credential on its own, so you do not need to take them in a set order.
Frequently Asked Questions
Are these the real ASE medium heavy truck test questions?
No. Heavy Duty Journal wrote every question here from scratch to match the ASE style and skills. They are not copied from ASE exams or any other publisher, so use them to find weak areas and learn the reasoning, not to predict your test.
How many questions are on the ASE T-series tests?
Scored questions run from 40 on T3 and T7 to 55 on T2, with 50 on the others. Each first-time test also has 10 unscored research questions. Recertification tests are shorter, from 20 to 28 questions, and have no unscored items.
What is the passing score for the ASE medium heavy truck tests?
ASE does not publish a passing score on the T-series page or in its study guide, so any specific percentage quoted elsewhere is unconfirmed. Aim to understand every content area on the test rather than a target percentage, and use the official ASE practice tests to gauge readiness.
Which ASE tests do you need for Master Medium-Heavy Truck Technician?
Master Medium-Heavy Truck Technician status requires T2 through T8: diesel engines, drivetrain, brakes, suspension and steering, electrical/electronic systems, HVAC and preventive maintenance inspection. T1 Gasoline Engines is not part of the Master title, so you can skip it if you do not work on gas trucks.
Does ASE offer official practice tests for trucks?
Yes, for four tests. ASE offers online practice tests with explanations for T2, T4, T6 and T8, and they are about half the length of the real tests. Vouchers are non-refundable and must be used within 60 days of redemption.
How much do the ASE medium heavy truck tests cost?
As of November 2026, ASE charges $62 per general test plus a $34 registration fee per order. Recertification tests are $62 each with a $186 cap on test fees, which makes the maximum recertification order $220 with registration. Check the current ASE fee page before you pay, since fees can change.
How much work experience does ASE require?
ASE requires hands-on work experience, or a combination of formal training and experience, and the study guide lists 2 years for this series. Only employed experience counts, not classroom time, and the certificate is delayed until ASE approves the experience.
The Bottom Line
ASE medium heavy truck practice questions are most useful when they show you where to study next. Work through each set of questions cold, read every explanation, match your misses to the content-area tables and follow up with ASE's official practice tests for T2, T4, T6 and T8. Then register inside a window, schedule the test within 90 days and keep your work experience records ready.
Michael Nielsen and the Heavy Duty Journal team publish ASE, training and shop guides at heavydutyjournal.com, and this page will be updated as ASE changes its tests, fees and rules. Verify current figures on ASE's own pages before you register, and find related certification guides on heavydutyjournal.com.
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Know a technician preparing for the ASE T-series tests? Share these ASE medium heavy truck practice questions so they can test themselves on all eight tests before they register.
