GMC Sierra T1XX (2019-Present) brake pedal goes to floor

Learn how to diagnose and fix the brake pedal going to the floor in GMC Sierra T1XX (2019-present). Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the parking brake is engaged.
• Disconnect the negative battery terminal.

2. Inspect and Replace Brake Fluid

• Check the brake fluid reservoir; if low, fill with manufacturer-recommended brake fluid (usually DOT 3 or DOT 4).
• If fluid was low, inspect for leaks as described in the diagnostic steps.

3. Repair or Replace Damaged Components

A. Brake Line Replacement (if leaking)

• Locate the damaged brake line.
• Use a line wrench to disconnect the line from the master cylinder and brakes.
• Install a new brake line, ensuring proper routing.
• Bleed the brake system to remove air.

B. Master Cylinder Replacement (if faulty)

• Remove the master cylinder by unscrewing the mounting bolts.
• Disconnect brake lines using a line wrench and remove electrical connectors if present.
• Install the new master cylinder and reconnect brake lines.
• Bleed the brake system thoroughly.

4. Brake Components Inspection

• Inspect brake pads and calipers for wear.
• Replace any worn brake pads or malfunctioning calipers as necessary.
• Reinstall wheels and lower the vehicle.

5. Final Checks

• Reconnect the negative battery terminal.
• Test the brake system by pressing the pedal multiple times to build pressure.