Question 23 of 140

As part of a pre-trip inspection, why do you pump the brake pedal several times with the engine off before checking anything else on the air system?

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To warm up the brake pads before driving
To release any residual air pressure so the low air warning and gauges can be tested from a realistic starting point
To make sure the parking brake light bulb is not burned out before driving, a routine bulb check unrelated to air pressure
To check that the horn still works

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Correct answer to question 23 (Air Brakes): To release any residual air pressure so the low air warning and gauges can be tested from a realistic starting point

Why

Pumping the brakes with the engine off deliberately drains the stored air, which is what lets you watch the pressure drop and confirm the low air warning triggers at the correct point rather than testing it from a full tank.

Updated: November 2026

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As part of a pre-trip inspection, why do you pump the brake pedal several times with the engine off before checking anything else on the air system?

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