Vehicle Mechanics and Inspection: Checks, Brakes, and Warning Lights
What this domain tests
Vehicle-mechanics questions cover pre-trip checks, warning lights, tyre condition, and brake behaviour. You need to know what a symptom means and what to do next.
Pre-trip checks
Check tyre pressure when cold and tread depth; the legal minimum for passenger cars is 1.6 mm. With the engine off and cool, the oil level should sit between the F and L marks. Check coolant, brake fluid, lights, and washer fluid. Never open a hot radiator cap.
Brakes and tyres
- ABS prevents wheel lock and keeps steering; a pulsing pedal during hard braking is normal - maintain pressure.
- Fade is loss of braking from overheating after repeated or long downhill use; downshift and use engine braking.
- Vapour lock is a spongy pedal caused by bubbles in hot brake fluid; stop and let it cool.
- Hydroplaning lifts the tyre off water; ease off the accelerator and avoid sudden inputs.
Warning lights
A red oil-pressure, brake, or coolant light means stop safely and investigate. Amber lights generally mean check soon.
Worked example
On a long mountain descent your brake pedal gradually travels further and the car slows less. That is fade, not a flat tyre. Correct action: release the pedal, select a lower gear for engine braking, and stop at a safe place to let the brakes cool. Continuing to ride the pedal makes it worse.
Traps that cost marks
Assuming ABS always shortens stopping distance; overinflating tyres to save fuel; ignoring a red oil light because the engine still runs; and opening the radiator cap while hot.