Practice question

Why does trailer air supply matter in combination-vehicle operation?

  1. The red trailer air supply control supplies air when pushed in and applies trailer emergency brakes when pulled out.
  2. Pull out to supply trailer air
  3. Use it only for trailer lights
  4. It has no effect on trailer brakes

Answer: A — The red trailer air supply control supplies air when pushed in and applies trailer emergency brakes when pulled out.

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