You should never drive your vehicle if the brake-system warning device:
Correct. A continuously lit or sounding low-air warning means dangerous brake-system pressure loss. Stop safely and have the system serviced.
CDL Practice Question #51
Category: General Knowledge
Why this question matters
This question is one of 97 in our General Knowledge bank. The reasoning above comes directly from the AAMVA CDL Manual, the source document used by every U.S. state DMV. Memorizing the underlying rule — not just the letter answer — is what separates passing on the first attempt from a return trip and another fee.