A driver reports that the parking brakes apply by themselves while driving. What is the most likely cause?

Practise this ASE T4 Truck Brakes Prep question free, then download the PDF, watch the video walkthrough, or unlock timed mock exams for the full web bank.

Download PDF Watch video

Multiple choice — select the best answer

ASystem air pressure dropping below approximately 40-60 psi
BA defective parking brake dash control valve
CBroken return springs in the brake assembly
DImproperly adjusted brake shoes

✓ Correct answer: A. System air pressure dropping below approximately 40-60 psi Spring brakes are designed to apply automatically when system air pressure drops below approximately 40-60 psi. A system air leak causing pressure to drop below this threshold would result in automatic application of the spring brakes while driving.

.q-expl{display:block!important}.q-opt[data-idx="0"]{border-color:#16a34a;background:#f0fdf4}.q-opt[data-idx="0"] .oltr{background:#16a34a;color:#fff}.q-opt{cursor:default!important;pointer-events:none}

Keep practising. Use the free ASE T4 Truck Brakes Prep PDF, watch the YouTube walkthrough, or unlock all 10 web questions with timed mock exams.

Free PDF Video walkthrough

← Previous Next → 🎲 Random question ↩ Back to all questions

Keep practising

A driver reports that the parking brakes apply by themselves while driving. What is the most likely cause?

Related questions

Free practice here. Timed mocks when you are ready.