ASE G1 Auto Maintenance and Light RepairBrakesMedium
A technician is inspecting a vehicle's brake system. They observe that the brake pedal requires excessive force to stop the vehicle, and the vehicle pulls to one side during braking. Upon inspection, they find that one of the front caliper pistons is seized. Which of the following is the MOST likely cause of these symptoms?
- AA clogged brake hose restricting fluid flow to one caliper.
- BContaminated brake fluid causing corrosion within the system.
- CWorn master cylinder seals allowing internal fluid bypass.
- DA faulty brake booster not providing adequate power assist.
Show answer & explanationAnswer & explanation
Correct answer: D. A faulty brake booster not providing adequate power assist.
A seized caliper piston would cause the vehicle to pull to one side due to uneven braking force, but the primary cause of excessive pedal effort for the entire system is usually a faulty brake booster. The booster assists the driver in applying the brakes, and without it, significant pedal force is required.
Why the other options are wrong
- A. A clogged brake hose would restrict fluid flow to only one caliper, causing a pull, but wouldn't typically cause excessive pedal effort for the entire system.
- B. Contaminated fluid can cause corrosion and component failure, but typically wouldn't cause a sudden increase in pedal effort across the entire system as the primary symptom, although it could contribute to a seized caliper.
- C. Worn master cylinder seals usually result in a spongy pedal or a pedal that slowly sinks to the floor, not excessive pedal effort.
Brake Booster Failure
A brake booster failure results in a hard brake pedal requiring significantly more force to stop the vehicle, as the power assistance is lost.
- Increases pedal effort
- Often accompanied by a pull if other components are also failing
- Vacuum or hydraulic assist
Memory trick: Hard Pedal, Hard Stop, Hard to Ignore the Booster.