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 large buses, at what pressure do the low pressure warning devices commonly activate?

   Correct answer: 80 to 85 psi

   While most vehicles warn below 55 psi, it is common for the low pressure warning on large buses to signal at 80 to 85 psi.

   Source: Section 5.1.11 - Low Air Pressure Warning

2. 2. How does the air brake system turn on the brake lights for traffic behind you?

   Correct answer: Through an electric switch operated by air pressure

   An electric stop light switch that reacts to air pressure lights up the brake lamps whenever the air brakes go on, warning drivers behind you.

   Source: Section 5.1.12 - Stop Light Switch

3. 3. What does a supply pressure gauge tell the driver?

   Correct answer: How much pressure is stored in the air tanks

   Every air brake vehicle has a supply pressure gauge tied to the air tank; it reports how much pressure the tanks are holding.

   Source: Section 5.1.9 - Supply Pressure Gauges

4. 4. If you keep having to increase application pressure just to hold the same speed, what is that telling you?

   Correct answer: The brakes are fading

   Needing more and more application pressure to keep a steady speed is a sign the brakes are fading; you should slow down and shift to a lower gear.

   Source: Section 5.1.10 - Application Pressure Gauge

5. 5. What color are the ABS malfunction lamps that warn of a fault?

   Correct answer: Yellow

   Vehicles with ABS use yellow malfunction lamps; on tractors, trucks, and buses they sit on the instrument panel, and on trailers they are placed on the left side.

   Source: Section 5.1.16 - Antilock Braking Systems (ABS)

6. 6. How does a 'wig wag' low-pressure warning device alert the driver?

   Correct answer: It drops a mechanical arm down into the driver's view

   The wig wag lowers a mechanical arm into the driver's line of sight when system pressure drops below 55 psi; an automatic one lifts back out of view once pressure rises above that mark.

   Source: Section 5.1.11 - Low Air Pressure Warning

7. 7. A visible low air pressure warning must switch on before tank pressure falls below what level?

   Correct answer: 55 psi

   The warning you can see has to come on before air pressure in the tanks drops under 55 psi (or half the governor cutout on older vehicles).

   Source: Section 5.1.11 - Low Air Pressure Warning