A brake pedal that slowly goes to the floor when the brakes are applied with no fluid loss could indicate the

• A. ABS Module
• B. Master Cylinder Is Defective
• C. Brake Lines
• D. Worn Brake Pads

Answer: (B)

A brake pedal that sinks toward the floor with no visible fluid loss points to an internal hydraulic leak, most often in the master cylinder. The master cylinder creates and maintains hydraulic pressure in the brake lines, and its seals can wear or fail so fluid leaks past inside the cylinder rather than out of the system. That means pressure bleeds off as you hold or push the pedal, causing the pedal to slowly drop and braking effectiveness to fade. Since the leak is internal, you might not see any puddles or wet spots, though the fluid level in the reservoir can change.

Other options don’t fit this symptom as well: an ABS module affects wheel lock control rather than sustaining hydraulic pressure; brake lines would usually show external leaks; worn brake pads affect pedal travel and stopping power but don’t typically cause the pedal to sink to the floor from pressure loss.