Pontiac Grand Prix brake pedal goes to the floor after master cylinder replacement, with knocking noise and vibration under gas pedal on Pontiac Grand Prix

Some Pontiac Grand Prix owners report experiencing issues where the brake pedal goes to the floor after replacing the master cylinder, accompanied by a knocking noise and vibration under the gas pedal. These problems may stem from improper master cylinder installation, which can prevent the necessary pressure from being generated, leading to a sinking pedal. Additionally, a brake fluid leak could be a contributing factor, as low fluid levels require not just a refill but also a thorough bleeding of the brake system. The illumination of the ABS and TC lights following the replacement of rusted brake lines may signal underlying issues with the anti-lock braking or traction control systems that need further inspection. To mitigate these concerns, owners are advised to ensure proper installation of the master cylinder, check for leaks, bleed the brake system to eliminate air, and inspect the ABS modulator for any faults. If these measures do not rectify the issues, consulting a professional mechanic is recommended for a comprehensive diagnosis and repair.