2026 Alabama Doubles - Triples CDL Practice Test 1

If your test of the tractor protection valve is successful,

the tractor protection valve control (trailer air supply control) will pop out or go from "normal" to "emergency." the parking brake valve will pop out. the low air pressure warning signal will come on.

Correct Answer:

the tractor protection valve control (trailer air supply control) will pop out or go from "normal" to "emergency."

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