Vehicle Systems
What the exam tests
Vehicle systems covers air brakes, tires, lights, engine, suspension, and warning devices. Questions test whether you understand what a warning means and what to check.
Core rules
- Air brake test: build pressure, check leakage, and test the low-pressure warning.
- Check tire pressure and tread before driving.
- Test lights, including brake lights and turn signals.
- Watch gauges for oil pressure, coolant temperature, and air pressure.
- Know what warning lights mean and stop when a critical one stays on.
Worked example
During an air-brake test, pressure drops faster than the allowable leak rate. The driver should not dispatch the vehicle until the leak is found and repaired. The reasoning is that a leak can reduce braking capacity, and the test is designed to catch it before a trip.
Traps that cost marks
- Ignoring a low-air-pressure warning and continuing to drive.
- Assuming ABS means normal brakes will always stop the vehicle.
- Skipping slack-adjuster checks.
- Treating a warning light as a nuisance rather than a signal to inspect.
Exam tip
Vehicle-system questions often ask what a warning means; the safe answer is to stop and check, not to keep driving.