Truck Maintenance: The Complete Guide for Heavy Duty & Commercial Fleets in Canada

Truck maintenance is the planned inspection, servicing and repair of a truck’s engine, brakes, tires, electrical system, drivetrain and safety equipment so it stays safe, legal and on the road. In practice, that means daily driver inspections, scheduled preventive maintenance (PM) services based on the manufacturer’s guidance, and records that show what was done and what was found. Skip those steps and the work still gets done, just later, at the roadside, and at a higher price.

This guide covers what maintenance includes, how to build a checklist and schedule, what each major system needs, what Canadian and Quebec conditions change, and how to tell when routine wear has become a repair.

What Is Truck Maintenance?

Truck maintenance covers every activity that keeps a truck safe, reliable and compliant. That includes the checks a driver performs before a trip, the scheduled PM services a technician performs, and the follow up work that comes from inspection findings.

It differs from repair in one important way. Maintenance is planned and proactive. Repair is what happens once something has failed or worn past its limit.

Heavy Duty vs Commercial vs Semi Truck Maintenance

These terms overlap, but the workload is different for each.

Heavy duty truck maintenance applies to Class 7 and Class 8 vehicles (generally above about 11,800 kg gross vehicle weight rating), including tractors, dump trucks and large vocational trucks. They typically run larger diesel engines, air brake systems and multiple drive axles, so there is more to inspect and more that can go wrong under load.

Commercial truck maintenance is the broader category. It includes heavy units and also medium duty delivery trucks, cube vans and service vehicles. Many of these use hydraulic brakes rather than air, and they often work in stop and go city traffic that wears brakes, clutches and suspension components quickly.

Semi truck maintenance centres on the tractor and trailer combination. On top of the tractor itself, it includes the fifth wheel, trailer coupling, trailer brakes, landing gear, lighting and the air and electrical connections between the two units.

Duty cycle matters as much as distance. A truck that idles a lot, stops often or hauls heavy loads over rough ground will need attention sooner than its odometer suggests.

Why Regular Truck Maintenance Matters for Canadian Operators

Canadian operators run equipment through long winters, repeated freeze and thaw cycles, road salt, rough pavement and long distances between service points. A weakness that goes unnoticed in summer, such as a marginal battery or a weeping air line fitting, often shows up at minus 30.

There is a business case too. A truck that is down is not earning, and unplanned repairs usually cost more than the same work done on schedule because they bring towing, rush parts and missed deliveries with them. Consistent maintenance also protects your inspection results and your safety record with regulators.

Truck Preventive Maintenance Explained

Truck preventive maintenance is a structured program of inspections, fluid and filter changes, adjustments and component replacements, performed at set triggers before parts fail. The aim is to find wear while it is still cheap to fix and easy to schedule.

You will see both “preventive” and “preventative” in the trade. They mean the same thing, and “preventive” is the more common form.

Preventive vs Reactive Maintenance

Preventive maintenance follows a plan. Reactive maintenance responds to a failure.

Preventive work is scheduled around operations, produces predictable costs and lowers safety and compliance risk. Reactive work usually happens at the worst moment, often at the roadside, and tends to cost more per event once towing, lost revenue and collateral damage are counted.

Reactive is not always the wrong choice. Running a low cost item that does not affect safety or uptime until it fails, such as a cab dome light, can be sensible. Brakes, tires, steering parts and anything tied to safety belong in the preventive category.

What Is a PM Service on a Truck?

A PM service is a scheduled visit that combines a standardized inspection with defined service tasks: oil and filter changes, lubrication, fluid checks, brake and tire measurements and a review of anything that looks marginal. Findings are recorded, and any repairs are quoted or scheduled.

A good PM does two jobs at once. It services what is due now, and it inspects what is not yet due so the next visit holds no surprises.

What Does PM Mean in Trucking?

In trucking, PM stands for preventive maintenance. When a dispatcher says a truck is due for a PM, the unit has reached its scheduled service point and needs to come in. You will also hear PM A, PM B and PM C, which are tiers of increasing depth explained in the schedule section below.

Truck Maintenance Checklist

A checklist defines what gets inspected. A schedule, covered in the next section, defines when. Keeping the two separate helps: the best checklists are short enough that drivers actually complete them and detailed enough that technicians catch what matters.

Start with items that apply to nearly every truck:

• Engine oil, coolant and other fluid levels
• Fluid leaks under the truck and around the engine
• Belts and hoses (cracks, fraying, soft spots)
• Tire pressure, tread depth and sidewall condition
• Brake operation and the condition of the air or hydraulic system
• All exterior lighting and reflectors
• Battery condition, terminals and charging output
• Steering play and suspension condition
• Windshield, wipers, washer fluid and mirrors
• Emergency equipment such as a fire extinguisher and warning devices

Then add the items specific to your vehicle type.

Heavy Duty Truck Maintenance Checklist

Add these for Class 7 and Class 8 units:

• Air brake build up time, leak down and governor cut in and cut out
• Brake chamber pushrod stroke and slack adjuster condition
• Air dryer function and moisture in the air tanks
• DEF level, quality and any aftertreatment warnings
• Fuel and air filter restriction indicators
• Driveshaft, universal joints and differential seals
• Kingpins and steering components for lubrication and play
• Exhaust system leaks, cracks and loose mounts

Commercial Truck Maintenance Checklist

For medium duty and delivery fleets, weight the checklist toward the parts that stop and go work punishes:

• Brake pads, rotors and drums, especially on hydraulic systems
• Clutch engagement and feel on manual transmissions
• Suspension bushings, springs and shocks
• Tire condition in every position, including duals
• Door, liftgate and body hardware
• Backup alarms, cameras and cab safety equipment

Semi Truck Maintenance Checklist

Add the connection between tractor and trailer:

• Fifth wheel jaw, lock, mounting bolts, lubrication and plate condition
• Gladhands, air lines, seals and the electrical cable
• Landing gear operation
• Trailer brakes, tires and lights
• Trailer kingpin and upper coupler plate
• Doors, tie downs and the refrigeration unit if fitted

Truck Preventive Maintenance Checklist

This is the technician’s version, used during a scheduled PM. It goes further than the driver’s walkaround:

1. Review driver defect reports and previous inspection findings.
2. Change oil and filters as specified by the engine manufacturer.
3. Check transmission, differential, power steering and coolant condition.
4. Measure brake lining or shoe thickness and inspect drums or rotors.
5. Measure tread depth at several points on each tire and note uneven wear.
6. Lubricate all grease points, including kingpins and driveline components.
7. Load test batteries and inspect cables and terminals.
8. Check steering linkage, suspension and signs of alignment problems.
9. Inspect lighting, wiring and connectors.
10. Record findings, parts used and any deferred work.

Expert tip: The last step is the most valuable. A record of what was found and what was postponed is what lets the next technician recognize a trend instead of a single symptom.

Truck Maintenance Schedule

A schedule assigns each check and service to a rhythm. Most fleets layer three levels: what the driver does daily, what gets checked weekly and monthly, and what happens at PM intervals.

Treat any interval you read online, including in this guide, as a starting point. The engine and component manufacturers’ service manuals, oil analysis results, duty cycle and operating climate should set your real numbers.

Daily / Pre Trip Checks

The driver’s walkaround catches many of the problems that can strand a truck. It should take a few focused minutes, not a few seconds and not half an hour.

• Walk around the truck and look underneath for fresh fluid
• Check engine oil and coolant levels
• Inspect tires for damage, low pressure and embedded objects
• Test all lights, including hazards and brake lights
• Check air brake build up and listen for leaks
• Check mirrors, wipers and windshield
• Confirm fifth wheel and trailer connections on tractor and trailer units

Pre trip inspections and defect reporting are legal obligations for commercial drivers in Canada, with details set by each province. In Quebec, heavy vehicle drivers must complete a documented safety check (the ronde de sécurité) and report defects. Confirm the current requirements for your vehicle class with the SAAQ.

Weekly Checks

Weekly checks cover items that change more slowly but can still surprise you:

• Battery terminals for corrosion
• Belts and hoses
• Tire pressure on every position, measured cold
• Air filter restriction indicator or a visual check
• Windshield and glass, since small chips spread
• Grease points that see heavy use

Monthly Checks

Monthly is a good rhythm for a closer look:

• Steering linkage and suspension for play or wear
• Brake lining wear and brake stroke
• Exhaust system and mounts
• Fuel filter and water separator
• Wheel ends, hub seals and signs of leakage
• Cab safety equipment, seat belts and HVAC

Semi Truck Maintenance Schedule

Tractor and trailer combinations need the same layers plus the trailer. Trailers are often the neglected half, especially when a fleet runs more trailers than tractors and units rotate between drivers.

Give each trailer its own service record and schedule. Trailer brakes, wheel ends, landing gear and lighting deserve the same discipline as the tractor. Fifth wheel lubrication and wear inspection belong on the tractor schedule, and many fleets check them at every PM.

Commercial Truck Maintenance Schedule

For medium duty and delivery trucks, engine hours and the calendar often work better than the odometer. A delivery truck may cover modest distances while spending long periods idling, braking and cycling doors and liftgates.

Set PM services by whichever trigger arrives first: time, engine hours or distance. Then inspect brakes and tires more often than the full PM interval, since stop and go duty consumes them faster.

PM A, PM B, PM C Explained

Many fleets use tiered services so each visit is sized to the need. Names and contents vary between shops, but the logic is consistent.

PM A is the frequent, basic service. It typically includes an oil and filter change, fluid top ups, lubrication and a basic inspection.

PM B includes everything in PM A and adds a deeper inspection of brakes, steering, suspension, the cooling system, belts and batteries. Its purpose is to catch wear before it becomes a failure.

PM C includes everything in PM B and adds major fluid services, drivetrain checks and detailed diagnostics. It works as a periodic deep service that resets your baseline understanding of the truck.

Intervals for each tier depend on the engine manufacturer’s recommendations, the oil used, oil analysis results and how hard the truck works. A highway tractor with steady running and a dump truck idling on a job site can sit at very different intervals. Mileage figures published for PM A, B and C are examples, not rules.

Mileage, Engine Hours, Calendar & Condition Based Triggers

Each trigger has strengths and blind spots:

• Mileage or kilometres suit highway linehaul work but ignore idling and stop and go wear.
• Engine hours suit vocational trucks and idle heavy work, but only if hours are tracked reliably.
• Calendar time suits low use or seasonal trucks, though it ignores actual use.
• Condition based triggers rely on oil analysis, telematics data and inspection findings. They are the most precise but demand data discipline and technical judgment.

Most well run fleets combine them, servicing at whichever threshold arrives first and adjusting intervals based on real findings. Clean oil and low wear metals may justify a longer interval. Fuel dilution or rising wear metals call for a shorter one and an investigation into the cause.

Key Truck Components to Maintain

The checklist tells you what to inspect. This section covers what tends to go wrong in each system and how to recognize it early.

Engine & Fluids

The engine depends on clean oil, correctly mixed coolant and reliable fuel delivery. Oil changes remove contaminants and renew additives, and coolant protects against overheating and corrosion.

Warning signs include oil level dropping between changes, coolant loss without visible leaks, milky oil (which can point to coolant intrusion), hard starting and unusual exhaust smoke. DEF problems, including contamination or freezing, can trigger aftertreatment warnings and power reduction.

Fluid leaks are early warnings. A small drip at a seal is an inexpensive fix. Ignored, it can drain a component during a trip.

Filters

Filters protect the engine, fuel system and hydraulics from contamination. The main ones are oil, fuel, air and cabin filters, along with the fuel water separator, which matters most in winter when condensation increases.

Replace filters on schedule or when restriction indicators show they are loaded. Dusty job sites, gravel roads and salt spray can shorten filter life. Filter replacement is one of the cheapest maintenance tasks with one of the biggest payoffs.

Tires

Tires are usually the largest recurring maintenance expense and are critical to safety. Check pressure when tires are cold, and measure tread depth across the full width of the tire, not in one spot.

Uneven wear is a diagnostic clue, not just a wear problem. It often points to alignment, suspension or inflation issues. Also watch for cuts, bulges, sidewall damage, mismatched duals (which force one tire to carry more load) and slow leaks. Under inflation builds heat and wears the shoulders, and it is a common contributor to sudden tire failure under load.

Brakes & Air System

Brakes deserve the most careful attention on any truck. On air brake trucks, inspect the whole system rather than just the friction material: lining thickness, drum condition, brake chamber pushrod stroke, air lines and fittings, the air dryer, the compressor and governor settings.

Trouble shows up as longer stopping distances, pulling to one side, a spongy pedal, or an air system that takes too long to build pressure. Any of these calls for prompt attention.

Expert tip: Most modern air brakes use automatic slack adjusters. If stroke is out of range, do not simply crank the adjuster. Out of range stroke usually points to a fault in the adjuster, the foundation brake or the linkage, and that fault needs to be found.

In winter, moisture in the air system is a specific risk. Water that freezes in valves or lines can cause brake problems, so a healthy air dryer and regular tank purging matter more once temperatures drop.

Electrical System

Modern trucks depend on electronics, so the battery, alternator, starter, wiring and connectors all need to be sound. Load test batteries rather than relying on a voltage reading alone. Clean corrosion from terminals, inspect cables, confirm alternator output and look for chafed wiring near moving parts.

Slow cranking is an early warning, not a nuisance. Cold weather exposes weak batteries quickly, and a battery that seems fine in October can fail in January. Testing before winter and again if starting becomes sluggish is inexpensive insurance.

Drivetrain

The drivetrain includes the transmission or gearbox, clutch on manual units, driveshaft, differential and axles. Warning signs include delayed or rough shifts, clutch slipping or hard engagement, driveline vibration (often from worn universal joints or imbalance), differential noise and seal leaks.

Drivetrain repairs are expensive, so early detection pays. Fluid sampling and attention to changes in noise or shifting behaviour are two of the best low cost early warning tools.

Steering & Suspension

Steering and suspension keep the truck controllable and the tires wearing evenly. Look for looseness in linkage and tie rod ends, worn king pins and bushings, leaking shocks, damaged springs or air bags, and loose mounting hardware.

Canadian roads add stress. Potholes formed by freeze and thaw cycles can bend components, throw off axle alignment and damage tires in a single impact. If a driver reports a hard pothole strike, have the front end checked rather than waiting for symptoms to develop.

Fifth Wheel & Trailer

The fifth wheel is a critical safety connection. Keep it lubricated, inspect the jaw and lock for wear, check mounting bolts and look for cracks in the plate. On the trailer side, inspect the kingpin, upper coupler plate, air connections, electrical plug and landing gear.

Fifth wheel lubrication is a small task, and neglecting it is one of the most common avoidable causes of accelerated wear and coupling trouble.

Lighting & Safety Equipment

Lighting defects are simple, cheap to fix and cited in roadside inspections again and again. Check headlights, brake lights, signal lights, hazard lights, marker lights and reflectors on both tractor and trailer.

A light that flickers usually points to a wiring, connector or ground fault that will get worse. Fix the cause, not just the bulb. Also confirm that required safety equipment is present and serviceable, including the fire extinguisher, warning devices and first aid kit.

Canadian & Quebec Truck Maintenance Requirements

In Canada, commercial vehicle safety is regulated mainly by the provinces and territories, guided by the National Safety Code. Two of its standards matter most here: Standard 13 on trip inspections and Standard 11 on maintenance and periodic inspection. Each jurisdiction applies them through its own laws, so requirements differ from one province to the next, which is worth remembering for carriers that cross provincial lines.

Winter Truck Maintenance

Winter truck maintenance is not a separate program. It is your regular program with sharper attention to the systems that cold weather stresses.

Before winter:

• Load test batteries and inspect cables
• Confirm block heaters and cab heaters work
• Check coolant concentration and condition
• Inspect belts and hoses, since cold makes worn rubber brittle
• Service the air dryer and purge moisture from the air system
• Use winter blend fuel and anti gel treatment as advised by your fuel supplier
• Check DEF storage and heating, since DEF begins to freeze at around minus 11°C
• Refill washer reservoirs with fluid rated for low temperatures
• Review tire condition and traction equipment for your routes

During the season, pay extra attention to fuel filters and water separators, lights covered in road film, and trailer air connections that can ice up.

Quebec Climate Considerations

Quebec adds a few specifics. Temperatures can swing widely within days, which accelerates freeze and thaw damage to pavement and to vehicle components. Road salt and brine exposure is heavy, so corrosion of frames, brake lines, air fittings and electrical connectors becomes a long term maintenance factor.

Three practical steps help:

1. Wash the undercarriage regularly during salt season, especially before parking for extended periods.
2. Inspect electrical connectors and protect them with dielectric grease where appropriate.
3. Look closely at brake lines, air fittings and frame areas for corrosion during every PM.

SAAQ & Canadian Compliance Basics

In Quebec, the SAAQ administers heavy vehicle safety programs and Contrôle routier Québec carries out roadside enforcement. Heavy vehicle owners are subject to mandatory mechanical maintenance requirements, while a recognized preventive maintenance program can provide an alternative to certain mandatory periodic mechanical inspections.

Other provinces run their own programs. Ontario, for example, requires annual safety inspections for commercial vehicles. Enforcement across Canada commonly refers to the CVSA North American Standard Out of Service Criteria when deciding whether a defect is serious enough to take a vehicle off the road.

Rules change and depend on vehicle class, weight and use, so confirm your current obligations directly with the SAAQ, Contrôle routier Québec or the authority in each province where you operate. Whatever the specifics, the fundamentals are the same: inspect, maintain to a defined program, repair defects promptly and document the work.

Maintenance Records & Fleet Preventive Maintenance

Maintenance without records is guesswork. With records, you can prove compliance, spot patterns and make better decisions about when to repair, refurbish or replace a unit.

Why Maintenance Records Matter

Records do four jobs:

• Compliance: Inspectors and auditors expect to see inspection reports, PM documentation and repair history.
• Diagnosis: A symptom repeated across several visits points to a root cause that a single visit might miss.
• Cost control: Records show which trucks cost the most to keep running and why.
• Resale and warranty: Complete service history supports resale value and helps in warranty discussions.

At a minimum, record the date, odometer reading, engine hours, work performed, parts used, technician and any deferred items.

Fleet Preventive Maintenance Planning

An owner operator can manage this with a notebook or spreadsheet. A fleet needs a system. A workable plan has five parts:

1. Baseline: Document each unit’s make, model, engine and the manufacturer’s service requirements.
2. Tiers: Set PM A, B and C intervals (or your equivalent) by unit type and duty cycle.
3. Scheduling: Plan PM visits around operations so trucks are not pulled during peak demand.
4. Open items: Track deferred work and make sure it is completed, not forgotten.
5. Review: Study breakdown causes at least once a year and adjust intervals and checklists to match.

Fleet management software and telematics can automate reminders and pull mileage and engine hours directly from the truck. Spreadsheets work for small operations but depend on someone remembering to update them. Choose the tool your team will actually use.

Tracking Mileage, Engine Hours & Service Dates

Track all three, because each tells a different story. Mileage shows distance, engine hours show how long the engine has worked, and service dates catch trucks that sit idle but still age.

A common mistake is relying only on the odometer. A vocational truck can log thousands of engine hours with little distance, and its oil and filters age accordingly. Where your data allows, record both readings on every work order.

When Truck Maintenance Becomes a Repair

Even the best program cannot prevent every failure. What matters is recognizing when routine wear has become a developing problem.

Signs Your Truck Needs Immediate Repair

Stop and have the truck inspected if you notice any of the following:

• Brake warning lights, a spongy pedal, pulling to one side or longer stopping distances
• An air system that will not hold pressure or builds it too slowly
• Steering that feels loose, wanders or vibrates
• Overheating, sudden loss of oil pressure or unexplained coolant loss
• Smoke from the engine bay or exhaust, especially with a burning smell
• Fluid leaks that are growing or leaving puddles
• Tire bulges, exposed cords or rapid pressure loss
• Persistent warning lights, engine derate or repeated fault codes
• Grinding, clunking or vibration from the drivetrain
• Electrical faults that cause lights, gauges or starting to fail intermittently

Driving on a known safety defect puts the driver, other road users and your compliance record at risk. When in doubt, stop.

When to Call a Truck Repair Company

Call a professional when the problem affects a safety system, when it needs diagnostic equipment, or when it goes beyond a roadside adjustment. Also call early when you are far from a shop, since mobile service can save a tow and the delay that comes with it.

Typical triggers include:

• A compromised brake, steering or air system
• A warning light or fault code that persists after basic checks
• A truck that cannot be moved safely
• A breakdown on the road or at a job site
• A defect that must be corrected before an inspection
• Repeat problems that suggest a deeper cause

For fleets in Quebec and across Canada, having a repair partner lined up before you need one makes a real difference. A shop that knows your PM history can also tell what is different this time, which speeds up diagnosis.

Emergency Roadside Service Coverage

If you experience a breakdown on major Quebec & Ontario corridors (Highway 20, 40, 401), our mobile units provide 24/7 service across Montreal, Laval, Longueuil, Vaudreuil-Dorion, Cornwall, and surrounding areas.

FAQ: Truck Maintenance Questions Answered