Signals & Pavement Markings

Study questions with answers

7 sample Signals & Pavement Markings questions with the correct answer, a short explanation, and the official handbook reference. Read through them, then take the quiz above.

1. 1. On most air-brake vehicles, a visible low-air warning must come on before tank pressure drops under:

   Correct answer: 55 psi

   A warning you can see is required and must appear before the tanks fall below 55 psi (or half the governor cut-out on older vehicles).

   Source: Section 5.1.11 - Low Air Pressure Warning

2. 2. Where should you look for a trailer's ABS malfunction lamp?

   Correct answer: On the left side, at a front or rear corner

   Trailer ABS malfunction lamps are yellow and located on the left side, either at the front or rear corner.

   Source: Section 5.1.16 - Antilock Braking Systems (ABS)

3. 3. On large buses, low-pressure warning devices commonly signal at about:

   Correct answer: 80 to 85 psi

   It is common for the low-pressure warning on large buses to activate earlier, around 80 to 85 psi.

   Source: Section 5.1.11 - Low Air Pressure Warning

4. 4. A supply pressure gauge on the dash reports which of the following?

   Correct answer: The amount of air stored in the tanks

   Supply pressure gauges show how much air the tanks hold. A dual system shows each half, either with two gauges or one gauge with two needles.

   Source: Section 5.1.9 - Supply Pressure Gauges

5. 5. On a newer tractor, the yellow ABS lamp finishes its start-up bulb check but then comes back on as you drive off. This most likely means:

   Correct answer: ABS control may be lost at one or more wheels

   If the malfunction lamp stays lit after the bulb check or lights up while driving, it warns that ABS may not be working at one or more wheels.

   Source: Section 5.1.16 - Antilock Braking Systems (ABS)

6. 6. A 'wig wag' low-air warning device works by:

   Correct answer: dropping a mechanical arm into the driver's view when pressure is low

   The wig wag lowers a mechanical arm into view when pressure falls below 55 psi; an automatic one lifts back out once pressure rises above that level.

   Source: Section 5.1.11 - Low Air Pressure Warning

7. 7. What does the stop light switch do on an air brake system?

   Correct answer: It turns on the brake lights when you apply the brakes

   An air-operated electric switch lights your brake lamps so drivers behind know when you are braking.

   Source: Section 5.1.12 - Stop Light Switch