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 a newer vehicle, what should the ABS malfunction lamp do when you start up?

   Correct answer: Light up briefly as a bulb check, then switch off

   On newer systems the warning lamp flashes on once at start-up to prove the bulb works, then goes dark; if it stays lit or comes on later, you may have lost ABS at one or more wheels.

   Source: Arizona CDL Manual — Section 5.1.16: Antilock Braking Systems (ABS)

2. 2. What is the 'wig wag' device found on some air brake systems?

   Correct answer: A mechanical arm that drops into the driver's view when pressure gets low

   The wig wag is a low-pressure warning that drops an arm into view when system pressure falls to about 60 psi; an automatic one lifts back out of view once pressure recovers.

   Source: Arizona CDL Manual — Section 5.1.11: Low Air Pressure Warning

3. 3. How does an air brake system light up the brake lamps to warn drivers behind you?

   Correct answer: Through an electric switch that is worked by air pressure

   An air-pressure-operated electric switch turns on the stop lamps whenever you apply the air brakes.

   Source: Arizona CDL Manual — Section 5.1.12: Stop Light Switch

4. 4. Where would you look for a trailer's yellow ABS malfunction lamp?

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

   Trailers carry their yellow ABS warning lamp on the left side, at the front or rear corner, while tractors, trucks, and buses show theirs on the instrument panel.

   Source: Arizona CDL Manual — Section 5.1.16: Antilock Braking Systems (ABS)

5. 5. What does the supply pressure gauge on an air-braked vehicle tell the driver?

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

   The supply gauge reads how much air is stored in the tanks; on a dual system there is one for each half, or a single gauge with two needles.

   Source: Arizona CDL Manual — Section 5.1.9: Supply Pressure Gauges

6. 6. A visible low-air-pressure warning is required to come on before tank pressure drops beneath what level on a typical vehicle?

   Correct answer: Below 60 psi

   The warning, usually a red light and often a buzzer, must appear before pressure falls below 60 psi; on many large buses it signals earlier, around 80 to 85 psi.

   Source: Arizona CDL Manual — Section 5.1.11: Low Air Pressure Warning

7. 7. You must push harder on the pedal to hold the same speed on a grade. Based on what the application pressure gauge indicates, what is this most likely a sign of?

   Correct answer: The brakes are fading, so ease off the speed and drop into a lower gear

   Needing more application pressure to keep the same speed points to fading brakes; it can also come from brakes out of adjustment, leaks, or mechanical trouble, so slow down and gear down.

   Source: Arizona CDL Manual — Section 5.1.10: Application Pressure Gauge