E. LearndmvDMV PRACTICE
Find your state Exam types Practice tests Sign in Create account ↗
Practice quizzes / Michigan CDL Combination Practice Questions - Michigan CDL Combination Vehicles Test Exam / Question 127125
Practice question

What can happen if trailer supply air is lost?

  1. Electrical cord supplies backup air
  2. Trailer emergency spring brakes can apply
  3. Trailer service brakes get smoother
  4. Fifth wheel releases

Answer: B — Trailer emergency spring brakes can apply

The correct answer is shown above. Try the full quiz for additional practice.

Practice more: Michigan CDL Combination Practice Questions - Michigan CDL Combination Vehicles Test Exam →
Learndmv.

Thoughtful practice for the road ahead. Find permit, road signs and CDL preparation by state.

Explore

Practice by stateAll practice testsExam types

Your account

My profilePractice historyAccount security

Get started

Create accountSign inSitemap
© 2026 LearndmvIndependent practice resource · Not affiliated with any state DMV.