A: Common Occupational Skills
6%of exam
B: Engines and Supporting Systems
16%of exam
C: Air Systems and Brake Systems
13%of exam
D: Electrical and Electronic Systems
16%of exam
E: Drive Trains
12%of exam
F: Steering, Chassis/Frames, Suspensions, Tires, Wheels, Hubs
13%of exam
G: Cabs
4%of exam
H: Trailers
6%of exam
I: Climate Control Systems
5%of exam
J: Hydraulic Systems
6%of exam
K: Hybrid and Electric Vehicles
3%of exam
Quick Facts
- Official questions
- 135 multiple-choice questions
- Writing time
- 4 hours
- Passing mark
- 70%
- Answer format
- Four options; one correct answer
- Blueprint
- 11 blocks; A–K
- Largest block
- Electrical/electronic systems; 22 questions
- Weights
- Published percentages; counts shown below
- Supplied references
- Trade formulas and acronyms
- Ontario identity
- Truck and Coach Technician; 310T
- Fees and rewrites
- Confirm provincial/territorial authority rules
Diagnostic Sequence
Confirm → Measure → Compare → Repair → Verify
Confirm: concern and conditionsMeasure: prescribed testsCompare: OEM expected valuesVerify: retest and document
Safe Test Picker
- Before work beneath raised truck→Rated support; secure against movement(OEM lift points and locks)
- Before high-voltage component work→Qualified technician; OEM isolation procedure(Discharge; verify with rated equipment)
- Before pressurized fuel line service→OEM shutdown, isolation, depressurization(Verify pressure safe before opening)
- Before cooling pressure test→Safe temperature; OEM test pressure(Correct tester and adapters)
- Excess automatic-adjuster stroke→Adjuster and foundation-brake cause diagnosis(Chamber-specific pressure and stroke limits)
- Before reefer inspection/service→Qualified service; disable automatic start(Isolate unit-specific energy sources)
- Slow hydraulic actuator→Flow, restriction, leakage tests(Specified load and operating conditions)
- Hydraulic injection puncture→Seek immediate emergency medical treatment(Identify injected fluid)
- Before multi-piece rim inflation→Trained personnel; prescribed restraining device(Stay outside possible component trajectory)
Safe Work
- Lockout
- Isolate, restrain, dissipate, verify energyBlock A: 8 questions
- Raised truck
- Rated supports; lock lift; restrain vehicle
- Hoisting
- Load, sling angle, anchor ratings
- Service identity
- VIN, component ID, current bulletins
- Fasteners
- OEM torque, sequence, replacement rules
- Fluid selection
- Application, climate, OEM grade
- Mentoring
- Demonstrate; learner practices; give feedback
Compression vs Leakage
Compression
- Measures developed cylinder pressure
- Specified cranking/test conditions
Leakage
- Introduces regulated test air
- Escape path helps locate leak
Measure sealing; then localize leakage
Engine Tests
- Compression
- Measures cylinder sealing performanceBlock B: 21 questions
- Leakage test
- Locates escaping test air
- Low oil-pressure warning
- Stop safely; verify specified gauge pressure
- CAC leaks
- OEM pressure-limited leak test
- Rail service
- OEM shutdown; isolate; verify depressurization
- Cooling test
- Safe temperature; OEM test pressure
- Engine retarder
- Supplements service-brake deceleration
Soot vs Ash
Soot
- Combustible trapped particulate
- Regeneration oxidizes it
Ash
- Noncombustible residue
- Specified cleaning/removal
Regeneration does not remove ash
Aftertreatment
- DPF
- Traps soot in porous filter
- Regeneration
- Oxidizes soot; leaves ash
- Ash
- Specified cleaning or filter replacement
- SCR
- DEF-supported catalytic NOx reduction
- Exhaust diagnosis
- Pressure, temperature, dosing; OEM tests
Relay Memory
Relay receives control; reservoir supplies chambers
Control line: foot-valve signalSupply line: local reservoir air
Service vs Spring Brake
Service chamber
- Air pressure applies braking
- Pedal-commanded brake demand
Spring chamber
- Spring applies parking brake
- Air releases powerful spring
No air still leaves spring energy
Air and Brake Checks
- Governor cut-in
- Compressor resumes chargingBlock C: 17 questions
- Governor cut-out
- Compressor unloads
- Air dryer
- Removes moisture; reservoirs still checked
- Relay valve
- Local reservoir supplies brake chambers
- Spring chamber
- Stored spring energy; never disassemble
- Brake stroke
- Chamber-specific limits and test pressure
- Automatic slack adjuster
- Excess stroke requires cause diagnosis
- ABS warning
- Codes and system tests required
Electrical Relationships
Voltage = current × resistance; DC power = voltage × current
V: voltsI: amperesR: ohmsP: DC power in watts
Series vs Parallel Batteries
Series
- Compatible voltages add
- Two 12 V → 24 V
Parallel
- Voltage remains nominally equal
- Compatible capacity increases
Follow OEM battery compatibility requirements
Electrical Test Picker
- No crank→Battery, loaded cables, start command(Retain safety interlocks; OEM tests)
- Normal battery; slow crank→Loaded power and ground drops(Compare OEM limits)
- Missing spark→Approved spark tester; supply/control checks(OEM spark-ignition procedure)
- Module will not communicate→Power, grounds, data-link tests(Vehicle wiring diagram)
- Resistance measurement needed→De-energize; discharge; isolate parallel paths(Follow applicable OEM procedure)
- Alternator output seems low→Specified speed/load; cable-drop tests(Check belt and regulator control)
- Code points to sensor→Test supply, ground, signal(Code alone does not prove failure)
- Intermittent electrical concern→Connections, wiring; logged data(Preserve codes before clearing)
- Electrical repair completed→Retest under specified operating conditions(Record tests and results)
Electrical Relationships
- Voltage
- V = I × RBlock D: 22 questions
- Current
- I = V ÷ R
- DC electrical power
- P = V × I
- Ideal 24 V; 6 Ω
- 4 A load current
- 24 V DC; 100 A
- 2,400 W electrical output
- Series 12 V batteries
- 24 V nominal; compatible pair
- Parallel 12 V batteries
- 12 V nominal; increased capacity
DTC vs Failure Cause
DTC
- Reports detected condition
- Guides diagnostic test selection
Cause
- Established by measurements
- May involve wiring or supply
Test before replacing named components
Electrical Diagnosis
- Voltage drop
- Measure across path under prescribed load
- Resistance mode
- De-energize; discharge; isolate parallel paths
- No crank
- Battery, loaded paths, interlocks, command
- Spark ignition
- Approved spark tester; supply/control checks
- No communication
- Power, grounds, network; wiring diagram
- DTC
- Detected condition; follow diagnostic tests
Drivetrain Checks
- Clutch release
- OEM bearing travel and linkage checksBlock E: 17 questions
- Automatic-transmission fluid
- Level at specified temperature/conditions
- AMT calibration
- After clutch replacement: specified calibration
- Driveline vibration
- Ride height, angles, phasing, joints
- Transfer case
- Distributes output to additional driven axles
- Axle ratio
- Ring teeth ÷ pinion teeth
- 41 ring; 10 pinion teeth
- 4.10:1 pinion-to-ring revolution ratio
Chassis and Wheel Checks
- Steer-tire wear
- Inspect pressure, play, bearings, suspensionBlock F: 18 questions
- Kingpin play
- Axle-specific loading, measurement, wear limits
- Air ride height
- OEM dimension; pressure varies with load
- Frame cracks
- Material/location-specific OEM repair procedure
- Coupler play
- Check wear, mounts, positive lock
- Multi-piece rim
- Trained service; restraint; outside trajectory
- Rim heat
- Never heat or weld rim components
- Wheel bearing
- Dial-indicator end play; hub-specific limits
Cab Checks
- Seat drops
- Inspect pneumatic supply, controls, leakageBlock G: 5 questions
- Wiper stalls
- Check linkage binding and electrical supply
- SRS service
- OEM isolation and capacitor discharge
- Cab tilt
- Support and lock using OEM procedure
Trailer Checks
- Landing gear
- Support trailer; inspect gearing/cross-shaftBlock H: 8 questions
- Reefer service
- Qualified technician; isolate automatic-start energy
- Defrost
- Removes evaporator ice; restores airflow
- Trailer structure
- Inspect corrosion, cracks, fasteners, flooring
- Trailer lighting
- Check circuit, connectors, ground; applicable rules
Climate Checks
- Evaporator
- Absorbs cab heat; refrigerant evaporatesBlock I: 7 questions
- Condenser
- Rejects heat; refrigerant condenses
- Low heater airflow
- Blower, filter, duct diagnosis
- Low heater temperature
- Coolant flow, core, temperature controls
- A/C recharge
- Identify refrigerant; recover; OEM charge
Hydraulic Pressure vs Flow
Pressure
- Force per piston area
- Load-related measurement
Flow
- Speed × effective piston area
- Measured under specified load
Pressure alone cannot establish delivered flow
Hydraulic Checks
- Hydraulic force
- F = A × PBlock J: 8 questions
- Piston area
- A = 3.14 × r²
- 50 mm bore; 10 MPa
- 19.625 kN ideal cap-end forceπ3.14; no losses/opposing pressure
- Slow actuator
- Test delivered flow under specified load
- Leak search
- Never use hands near pressure leaks
- Injection injury
- Immediate emergency treatment; identify injected fluid
Energy Control
Identify → Isolate → Control → Verify
Identify: all energy sourcesIsolate: vehicle-specific procedureControl: stored-energy hazardsVerify: rated equipment and PPE
High-Voltage Safety
- Qualified HV technician
- Vehicle-specific training, rated tools, required PPEBlock K: 4 questions
- Isolation
- OEM high/low-voltage and charging isolationHybrid engine sources also isolated
- Discharge
- Observe vehicle-specific stored-energy discharge procedure
- Verification
- Rated meter, required PPE; prove isolation
Common Traps
Ignition-off vs isolation
Ignition-off stops a command ≠ Isolation controls all hazardous energy
Zero air vs zero energy
Chamber air can be exhausted ≠ Spring still stores mechanical energy
Code vs failed component
Code reports a detected condition ≠ Tests establish the failure cause
Dryer vs dry reservoirs
Dryer removes most moisture ≠ Reservoir checks/draining remain specified
Stroke correction vs repair
Manual readjustment may hide excessive stroke ≠ Repair identified cause; verify stroke
Nominal vs measured voltage
Nominal voltage names the system ≠ Measured voltage depends on operating conditions
Last Minute
- 1.135 questions; four hours; 70% pass
- 2.Electrical block: 22; engines: 21 questions
- 3.Ontario: Truck and Coach Technician, 310T
- 4.Loaded voltage-drop tests reveal unwanted resistance
- 5.Resistance tests require de-energized, discharged circuits
- 6.Regeneration burns soot; ash requires cleaning
- 7.Spring-brake energy remains without air pressure
- 8.Brake-stroke limits require chamber-specific test conditions
- 9.Inspect wear before changing steering geometry
- 10.Reefer service requires automatic-start energy isolation
- 11.Hydraulic injection needs immediate emergency treatment
- 12.Qualified HV work: isolate, discharge, verify
- 13.Verify repairs under specified operating conditions
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