New Jersey CDL — Air Brakes practice
Traffic Laws
Speed limits, turning and signaling rules, headlight and seat-belt requirements, and the everyday laws every driver must follow.
Questions reviewed against the official New Jersey driver handbook · July 7, 2026
2 questions · pass with 2 correct. You get instant feedback and an explanation after every answer.
Study questions with answers
2 sample Traffic Laws questions with the correct answer, a short explanation, and the official handbook reference. Read through them, then take the quiz above.
1. How does an air brake vehicle turn on its brake lights for drivers behind it?
Correct answer: An air-pressure-operated electrical switch that lights the brake lamps
The stop light switch is an electrical switch operated by air pressure; when you apply the brakes it lights the brake lamps so following drivers are warned.
Source: New Jersey Commercial Driver License Manual, Section 5.1.12 - Stop Light Switch
2. Before the air pressure in the tanks drops below what level must a visible low-air-pressure warning come on?
Correct answer: Below 55 psi
A low air pressure warning is required, and the visible signal has to activate before tank pressure falls under 55 psi so the driver gets warning in time.
Source: New Jersey Commercial Driver License Manual, Section 5.1.11 - Low Air Pressure Warning
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Every New Jersey question is written from the official New Jersey driver handbook and checked against its current edition. DMV Test Free is a free, independent study resource — not affiliated with any DMV or government agency. About DMV Test Free