DFFT Brakes and Braking Systems 1 — Questions and Answers
Question 1: A vehicle pulls to one side when the brakes are applied. What is the most likely cause?
- Uneven brake pad wear or a seized caliper on one side (Correct answer)
- Low brake fluid level in the reservoir
- Worn brake rotors on both axles
- Air in the brake lines throughout the system
Correct answer: Uneven brake pad wear or a seized caliper on one side
Uneven braking force caused by a seized caliper or uneven pad wear causes the vehicle to pull toward the side with more braking force.
Question 2: A customer reports a spongy brake pedal that goes nearly to the floor. What is the most likely diagnosis?
- Air in the hydraulic brake lines (Correct answer)
- Worn brake pads on the front axle
- Sticking rear drum brake shoes
- A loose brake caliper mounting bolt
Correct answer: Air in the hydraulic brake lines
Air is compressible, so air trapped in the hydraulic lines causes a spongy, low pedal feel instead of firm hydraulic resistance.
Question 3: Brake fade occurs during repeated heavy braking. What is the primary cause of this condition?
- Overheated brake pads losing friction coefficient (Correct answer)
- Low brake fluid level
- Worn brake rotors below minimum thickness
- A cracked brake drum
Correct answer: Overheated brake pads losing friction coefficient
Excessive heat causes brake pad material to vaporize or glaze, dramatically reducing the friction needed to slow the vehicle.
Question 4: A grinding noise is heard when the brakes are applied. What does this indicate?
- Brake pads worn down to the metal backing plate (Correct answer)
- Air trapped in the brake caliper
- Warped front brake rotors
- Low brake fluid pressure
Correct answer: Brake pads worn down to the metal backing plate
When pad friction material is completely worn away, the metal backing plate contacts the rotor directly, causing a grinding metal-on-metal noise.
Question 5: A vehicle with ABS has a warning light on and the pedal pulses abnormally during normal stops. What should be checked first?
- Wheel speed sensors and their wiring harness (Correct answer)
- Brake master cylinder bore condition
- Brake fluid condition and boiling point
- Rear brake drum adjustment
Correct answer: Wheel speed sensors and their wiring harness
A faulty or damaged wheel speed sensor sends incorrect signals to the ABS control module, triggering the warning light and causing improper ABS activation.
Question 6: A high-pitched squealing noise occurs whenever the brakes are lightly applied. What is the most likely cause?
- Brake pad wear indicators contacting the rotor (Correct answer)
- A warped brake rotor causing vibration
- Air in the front brake calipers
- Brake fluid contaminated with moisture
Correct answer: Brake pad wear indicators contacting the rotor
Most brake pads have built-in metal wear indicators that squeal against the rotor to warn the driver when pads are due for replacement.
DFFT Brakes and Braking Systems 1
A vehicle pulls to one side when the brakes are applied.
What is the most likely cause?