DFFT Brakes and Braking Systems 2

Question 1

A brake pedal slowly sinks to the floor when held under constant pressure. What is this condition called?

Accepted Answer

Brake pedal creep caused by a faulty master cylinder

Answer

A worn or damaged master cylinder internal seal allows fluid to bypass under sustained pressure, causing the pedal to slowly sink.

Question 2

During a DFFT inspection, you find one brake rotor has a blue discoloration. What does this indicate?

Accepted Answer

The rotor has been subjected to excessive heat

Answer

Blue discoloration on a brake rotor is a sign of overheating, which can alter the metal's hardness and cause the rotor to warp or crack.

Question 3

A vehicle's parking brake fails to hold the car on a moderate hill. What is the most likely cause on a rear-drum brake vehicle?

Accepted Answer

Stretched or corroded parking brake cable

Answer

A stretched or corroded cable prevents the parking brake mechanism from applying sufficient force to hold the rear drum shoes against the drum.

Question 4

After a brake job, a customer returns complaining the brake pedal is very hard to press. What was likely the fault in the repair?

Accepted Answer

The brake booster vacuum hose was not reconnected

Answer

The brake booster uses engine vacuum to multiply pedal force; without vacuum supply, the driver must overcome hydraulic resistance unassisted, making the pedal feel very hard.

Question 5

A customer reports the brake pedal vibrates when stopping at highway speed. What is the most likely cause?

Accepted Answer

Warped or uneven brake rotors

Answer

Warped rotors cause the caliper piston to rapidly advance and retract as the high and low spots pass, creating a pulsating vibration felt through the pedal.

DFFT - Driver Fault Finding Test Practice Test

DFFT - Driver Fault Finding Test Practice Test

DFFT Brakes and Braking Systems 2