Ten free 310T Truck and Coach Technician practice questions.

Ten 310T Truck and Coach Technician questions in the format of the Red Seal exam: four options, one correct answer, no trick questions. They are free to use, print and share. There is nothing to sign up for on this page.

01How to use these

The questions come from the TicketPrep 310T bank and are spread across the exam's work activities in the order and roughly the proportion the Red Seal Program publishes for this trade: A (performs common occupational skills), B (services, diagnoses and repairs engines and supporting systems), C (services, diagnoses and repairs air systems and brake systems), D (services, diagnoses and repairs electrical and electronic systems), E (services, diagnoses and repairs drive trains), F (services, diagnoses and repairs steering, chassis/frames, suspensions, tires, wheels and hubs), H (services, diagnoses and repairs trailers), J (services, diagnoses and repairs hydraulic systems). Answer each one before opening the explanation. Every explanation covers all four options, because on the real exam the wrong options are written to be plausible, and knowing why they are wrong is most of the skill.

• Pace. The exam allows four hours for 135 questions, so about 1 min 47 s per question. Try these at that pace.
• Print. The printed version shows the questions and the answer key without the explanations, so it works as a handout. Print this page
• Mark. The pass mark is 70 percent on every Red Seal trade; seven of ten here is the same bar.

02The questions

1. Critical · Performs common occupational skills

   A highway tractor has been idling for 20 minutes in a closed bay with the overhead door down. A technician working nearby feels dizzy and nauseous, and a coworker across the bay has slumped against a bench. What is the most likely cause and the first action?

   1. Low blood sugar; the workers should sit down until they feel better.
   2. Carbon monoxide from the exhaust; get everyone out and ventilate the bay.
   3. Refrigerant leak from the cab air conditioner; open the cab doors.
   4. Heat exhaustion from the running engine; give both workers water and rest.
   Show the answer

   B. Correct. Diesel exhaust in an unventilated enclosed space builds up carbon monoxide, which is odourless and causes exactly these symptoms. Evacuate, open doors, shut the engine down only if it can be done without delay, call for help, and use the AED if the collapsed worker has no pulse. Exhaust extraction must be connected before an engine runs indoors.

   Why not the others

   A. Two people developing symptoms at the same time in the same closed bay points to the shared atmosphere, not to individual health. Sitting down in the contaminated space keeps them exposed. Get out, ventilate, and get help.

   C. A cab A/C leak releases a small refrigerant charge that would not affect two people across a bay. The idling engine in a closed bay is the obvious source of a bay-wide atmosphere problem, and the response must remove people from the space, not just open a cab.

   D. An idling engine does not raise a bay's temperature enough to cause collapse in 20 minutes, and treating for heat while leaving people in a contaminated atmosphere delays the response that matters. Exhaust gas in an enclosed space is the hazard to eliminate first.

2. Procedural · Services, diagnoses and repairs engines and supporting systems

   A technician is collecting an engine oil sample from a highway tractor for laboratory analysis. When and how should the sample be drawn so the result is representative?

   1. From the dipstick tube with a sampling pump, engine warm, before the oil is changed.
   2. From the drain plug at the start of an oil change, after the engine has cooled overnight.
   3. From the oil filter housing after the filter has been removed.
   4. From the new oil container, so the lab has a clean baseline.
   Show the answer

   A. Correct. A warm engine that has just been running keeps wear metals and contaminants suspended, and a vacuum sampling pump through the dipstick tube (or a dedicated sampling valve) draws from mid-sump rather than the bottom. The sample is taken before new oil goes in, using the kit's clean tubing and bottle, and labelled with the hours or kilometres. The RSOS requires samples to be collected according to the sample kit instructions and the manufacturer's information, and visually inspected before being sent.

   Why not the others

   B. A cold, settled sump lets contaminants and wear metals stratify, and the first fluid out of a drain plug carries the sludge from the bottom of the pan. Neither gives a representative picture of what is circulating.

   C. Oil in the filter housing is a mix of trapped debris and whatever drained back when the filter came off. It is not representative of the oil circulating in the engine.

   D. A baseline of new oil can be useful once, but the sample the RSOS is describing is the used oil, because it is the used oil that reveals component wear and contamination.

3. Critical · Services, diagnoses and repairs engines and supporting systems

   A coach has an active fault for SCR efficiency and the driver reports a warning about a coming derate. The technician finds heavy white crystal build-up around the DEF injector tip and in the decomposition tube. What does this indicate?

   1. The DPF has failed and is sending ash downstream.
   2. The DEF tank is contaminated with diesel.
   3. Normal deposits that every SCR system forms.
   4. Undecomposed DEF; check spray and dosing.
   Show the answer

   D. Correct. Urea crystals form when DEF is injected into exhaust that is too cool, or is over-dosed, or is delivered as a stream rather than a fine spray by a fouled or failing injector, and the deposits then reduce SCR efficiency and trigger the inducement sequence. The RSOS lists looking for accumulation of urea crystals among the sensory inspections and warning lights and fault codes among symptoms; the technician cleans the deposits, tests the injector and dosing pump, and checks the exhaust temperature sensors and duty cycle that led to low temperatures.

   Why not the others

   A. Ash is grey and would appear in the outlet of the DPF; white crystalline deposits at the DEF injector are urea, not ash.

   B. Diesel in the DEF causes dosing faults and pump damage, but the visible symptom is not crystal build-up. Crystals are urea that failed to decompose.

   C. A light film can form, but heavy crystal build-up is a fault condition that disrupts DEF spray and mixing and reduces NOx conversion. It is not normal.

4. Procedural · Services, diagnoses and repairs air systems and brake systems

   During a periodic inspection the technician checks the air compressor governor on a highway tractor. According to NSC Standard 11, what are the acceptance conditions?

   1. The governor is not inspected; only the compressor is.
   2. Cut-in and cut-out must be exactly 40 kPa (6 psi) apart.
   3. Any cut-out above 690 kPa (100 psi) is acceptable.
   4. OEM values; cut-out never above 1000 kPa (145 psi).
   Show the answer

   D. Correct. NSC Standard 11 (Section 3A, item 2, governor) requires the governor to be operative and free of leaks, with the cut-in pressure no lower than the manufacturer prescribes and the cut-out neither below nor above the manufacturer's value, and in no case above 1000 kPa (145 psi). The RSOS requires air pressures to be measured against the manufacturer's information and jurisdictional regulations, and governing pressures to be adjusted accordingly. Values are read on an accurate test gauge, since the dash gauge is only required to be accurate within 7 percent of cut-out.

   Why not the others

   A. The governor is a listed inspection item with its own reject conditions in NSC 11.

   B. The spread is set by the manufacturer, not fixed by the standard. The standard references OEM values.

   C. The standard sets the OEM's value as the requirement and 1000 kPa (145 psi) as an absolute ceiling; a cut-out merely above 690 kPa is not the criterion.

5. Procedural · Services, diagnoses and repairs electrical and electronic systems

   A technician checks a vented lead-acid battery with a hydrometer and gets 1.265 in five cells and 1.200 in the sixth, all corrected to 27 °C (80 °F). What does this reading pattern indicate and what should be done?

   1. One cell is failing; replace the battery.
   2. The low cell needs electrolyte; top it up with acid.
   3. The battery is fully charged; return it to service.
   4. The battery needs charging; put it on the charger overnight.
   Show the answer

   A. Correct. A difference of more than about 0.050 between cells indicates a defective cell, and 1.265 against 1.200 is a 0.065 spread. Charging cannot fix a bad cell. The RSOS requires specific gravity to be measured in each cell precisely so that this comparison can be made and the faulty battery replaced.

   Why not the others

   B. Electrolyte is topped up with distilled water, never acid, and only when the level is low. Adding acid to a weak cell raises its reading without fixing the plates, and masks the defect.

   C. Five cells are at full-charge specific gravity, but the sixth is well below them. A healthy battery's cells read within a few thousandths of each other; one low cell is not a charged battery.

   D. An undercharged battery reads low in all cells, not in one. Charging a battery with one weak cell overcharges the other five and does not restore the sixth.

6. Critical · Services, diagnoses and repairs electrical and electronic systems

   A driver reports a loud grinding noise every time the engine is started, and the engine sometimes needs a second try before it cranks. What is the most likely cause?

   1. Low battery voltage.
   2. Worn ring gear or damaged drive pinion.
   3. Air in the fuel system delaying the start.
   4. A slipping alternator belt.
   Show the answer

   B. Correct. Grinding at engagement with occasional failure to crank is the pinion failing to mesh cleanly with the ring gear: worn or broken ring-gear teeth (often in one spot where the engine habitually stops), a chipped drive pinion, or incorrect drive air gap or starter mounting. The RSOS lists noisy starter operation and intermittent operation among symptoms, and setting starter drive air gap and replacing starter drives among rebuild methods. Inspect the ring gear through the access cover and check the starter mounting is tight.

   Why not the others

   A. Low voltage produces slow or no cranking and a chattering solenoid, not a grinding at the flywheel. The mechanical noise is at the pinion-to-ring-gear interface.

   C. Fuel problems make an engine crank without firing; they do not make the starter grind. The grinding is mechanical and occurs whether or not the engine fires.

   D. A slipping belt squeals and does so while the engine is running, not at the moment of starter engagement. The noise timing ties it to the starter drive.

7. Critical · Services, diagnoses and repairs drive trains

   A driver reports that a tractor's engine speed climbs under load on grades without a matching increase in road speed, and there is a burning smell afterward. Pedal free play has disappeared. What is the diagnosis?

   1. Low transmission oil.
   2. A slipping clutch.
   3. A failed torque converter.
   4. A worn synchronizer.
   Show the answer

   B. Correct. Engine rpm rising without road speed rising is the clutch slipping, and the smell is the facing burning. Free play that has vanished is the mechanism: as the disc wears the release bearing moves and, without adjustment, ends up holding the clutch partly released so it cannot clamp fully. The RSOS lists slipping clutch, high engine rpm and loss of pedal free play among clutch symptoms and worn parts among faults; the technician checks whether adjustment restores free play and clamp, and if the disc is worn out or oil-contaminated, replaces the clutch.

   Why not the others

   A. Low oil causes noise and eventual gear damage; it does not produce slip between engine and transmission.

   C. This is a manual transmission with a clutch; there is no torque converter.

   D. Synchronizer wear causes grinding on shifts, not engine speed running away under load.

8. Procedural · Services, diagnoses and repairs steering, chassis/frames, suspensions, tires, wheels and hubs

   During a periodic inspection a technician must check king-pin wear on a highway tractor's steer axle. Which method gives the measurement the inspection standard requires?

   1. Visual inspection for grease leakage at the pin.
   2. Measure steering-wheel free play at the rim.
   3. Dial indicator, axle raised, wheel rocked.
   4. Rock the wheel by hand and judge the play.
   Show the answer

   C. Correct. NSC 11 Section 4 item 4: raise the axle to unload the kingpin, rock the wheel in and out by hand or with a bar and read lateral movement at the outer edge of the tire, then place a bar under the tire and read vertical movement; use a dial gauge where needed, with wheel-bearing play taken out first. Limits are the manufacturer's; only when none is published does NSC 11 default to 3 mm lateral (wheels under 20 in.), 5 mm lateral (20 in. and larger) and 2.5 mm vertical. The RSOS lists king pins among the components measured for end play and dial indicators and pry bars among the tools.

   Why not the others

   A. Grease condition is noted, but wear is a measured value, not a visual one.

   B. Steering-wheel free play is a separate inspection item that includes every joint in the system. It cannot isolate the king pins.

   D. Rocking the wheel is how the movement is produced, but judging it by feel gives no number to compare to the manufacturer's limit and cannot separate king-pin play from wheel-bearing play; the standard has the movement measured.

9. Critical · Services, diagnoses and repairs trailers

   During a trailer PM the technician finds the sliding bogie's locking pins will not fully seat in the rail holes on one side, and the rail is worn and elongated at that position. What is the significance?

   1. Add grease so the pins slide easier.
   2. Weld the bogie in one position.
   3. The bogie can shift; repair rail and pins.
   4. Normal; the pins only need to be partly in.
   Show the answer

   C. Correct. The sliding tandem is held in position only by its locking pins in the bogie rails; pins that cannot seat because the holes are elongated or the rail is worn can release under braking or on a bump, letting the axles slide, which can cause a loss of control. The RSOS lists bogie rails among trailer components and wear and loose fasteners among faults; the rails are repaired or replaced per the manufacturer (often by a certified welder), the pins and their springs checked, and the lock's operation verified. The trailer is out of service until repaired.

   Why not the others

   A. Lubrication does not fix elongated holes or a worn rail.

   B. Welding the slider defeats its function and is not a manufacturer-approved repair.

   D. Pins must be fully seated to hold the load; partial engagement is a release waiting to happen.

10. Procedural · Services, diagnoses and repairs hydraulic systems

    A technician needs to work under the raised box of a dump truck to service the hoist cylinder. What must be in place first?

    1. A coworker watching the lever.
    2. Mechanical support of the raised box.
    3. The control lever tied in the raise position.
    4. The engine running so the pump holds the box.
    Show the answer

    B. Correct. The RSOS requires raised components to be supported mechanically to prevent accidental dropping of the component or load. Hydraulic pressure alone can be lost through a leaking fitting, a valve spool shift or a failed hose, and the box comes down; the manufacturer's safety prop or an engineered stand takes the load before anyone goes under. The circuit's stored energy is then relieved for the work on the cylinder.

    Why not the others

    A. A person cannot react fast enough to a hydraulic failure. The support is mechanical.

    C. Holding the valve open still relies on hydraulic pressure and can over-extend the cylinder.

    D. Pump pressure is not a support; a hose failure drops the box regardless of the engine.

03Answer key

04More free questions

The same format for the other five trades, plus the free guides on the pass mark, question counts, exam day and how to study.

How these questions are written and checked: how our questions are made. Found a mistake? Tell us and we will fix it.