Open ProvincesHow a car works: engine, transmission, brakes, suspension and electrical systems
Understand how the main vehicle systems work together, what common dashboard warnings can mean and when to stop driving.
Adapted from a guide first written for Quebec readers: passages specific to Quebec were removed. Rules in your province may differ.
A car is a set of systems that work together to move, steer, slow and protect the vehicle. Knowing the broad purpose of each system can help you describe a problem to a mechanic, but a dashboard light or symptom alone rarely identifies one failed part.
The systems that move the vehicle
- Power source: a gasoline engine burns fuel; a hybrid combines an engine with electric drive; a battery-electric vehicle uses electric motors.
- Transmission and driveline: deliver power to the wheels and adjust how it is applied. Their design varies across front-, rear- and all-wheel-drive vehicles.
- Cooling and lubrication: help the engine or other components operate within their designed range and reduce wear.
The systems that control and protect it
- Brakes: convert motion into heat to slow or stop the wheels; warning lights, grinding, pulling or a changed pedal feel need prompt attention.
- Steering and suspension: guide the wheels and help keep tire contact with the road. New vibration, clunks or pulling can have several causes.
- Tires: provide the contact patch for acceleration, braking and cornering. Pressure and wear affect grip and handling.
- Electrical and electronic systems: power starting, lighting, sensors and control modules. A low battery or wiring fault can cause several seemingly unrelated symptoms.
Use diagnostic codes as clues
An OBD-II code identifies a detected condition or circuit, not necessarily the exact component that must be replaced. A technician may need to check symptoms, wiring, live data and service information before diagnosing the cause. Do not clear a warning simply to hide it before selling the vehicle or having it inspected.
If the brake warning is accompanied by a loss of braking, the engine is overheating, a tire is failing, smoke or a burning smell appears, or the vehicle cannot be controlled normally, stop in a safe place and seek qualified assistance.
Sources and limits
Vehicle designs and warning meanings vary; this overview is educational, not a diagnosis or repair procedure.
General information based on federal and national rules; provincial rules may differ. Confirm with the official body before acting.