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General Knowledge · Antilock Braking Systems

If a vehicle's ABS malfunction lamp stays on after starting the engine, what should the driver do?

1.Drive cautiously, avoid hard braking that could lock the wheels, and have the system inspected; the normal service brakes still workCorrect answer
2.Stop driving the vehicle immediately and refuse to move it under any circumstances until it has been repaired
3.Ignore the lamp entirely, since ABS has no real effect on braking performance on any vehicle one way or another
4.Assume the normal service brakes will also fail, since ABS and the service brakes are really the same system under one set of controls

Explanation

A lit ABS malfunction lamp means the anti-lock function may not be working, but the vehicle's ordinary service brakes still function, so the correct response is cautious driving, avoiding the hard braking that ABS would normally help control, and getting the system inspected. 49 CFR 383.111(a)(3)(ii) names this emergency-procedure knowledge area without stating the specific response, so it is standard driver-training content, attributed to the manual. The wrong options each get the relationship between ABS and the service brakes wrong: refusing to drive treats a lamp warning as if the brakes themselves failed, ignoring it denies that ABS provides any real benefit, and treating ABS and the service brakes as one system misunderstands that ABS only modulates braking that is otherwise still fully functional.

Source: 49 CFR 383.111(a)(3)(ii)

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