Washington CDL Practice Test

The red 8-sided 'Trailer Air Supply' knob on the dash is:

Pushed in to supply air to the trailer; pulled out to apply trailer emergency brakes Pulled out to supply air to the trailer Always left in the out position when driving A pressure gauge, not a control

Correct Answer:

Pushed in to supply air to the trailer; pulled out to apply trailer emergency brakes

Access more questions from this quiz

Continue to Washington CDL Practice Test for more practice questions and the full quiz experience.

Access More Questions