Your trailer ABS warning lamp is on. The trailer service brakes:
Correct. Trailer service brakes still work normally without ABS. Have the system repaired; ABS gives extra control during emergency braking.
CDL Practice Question #196
Category: Combination Vehicles
Why this question matters
This question is one of 55 in our Combination Vehicles 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.