ASE A5 Practice Test (Brakes) Answered 1. A vehicle is equipped with a vacuum brake booster. It doesn't have power assist until the engine runs for a minute, then it begins to work normally. What is the most likely reason? A. Defective check valve B. Adjusted brake pedal push rod is too short C. Front brake disc is worn D. Engine requires a tune-up to produce a higher vacuum at idle speed: Cor- rect answer A-The defective check valve causes a loss in vacuum when the engine is off. That's why the power assist begins to function properly after the engine runs. The other three answers wouldn't cause the same issues. 2. The brake pedal starts to feel spongy and low even though all the adjust- ments have been made according to the specifications. What could be the cause of the problem? A. Dented brake line B. Binding pedal linkage C. Weak hydraulic hose D. Plugged compensating port: Correct answer C-The weak hydraulic brake hose causes a spongy pedal. The pressure can continue to build and the hose might expand, but not release the pressure to the brake units. Binding pedal linkage would lead to a hard pedal, which is also true for a dented brake line. The plugged compensator port leads to dragging brakes instead.

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