why does my Toyota Highlander Fourth Generation (2020-present) brake pedal feel spongy when I press...

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and engage the parking brake.
• Disconnect the negative battery terminal to avoid electrical issues.

2. Brake Fluid Inspection

• Sub-steps:
  • Locate the brake fluid reservoir under the hood.
  • Check the fluid level; it should be between the minimum and maximum marks.
  • If low, top off with the recommended brake fluid (typically DOT 3 or DOT 4).

3. Leak Inspection

• Sub-steps:
  • Visually inspect all brake lines and hoses for signs of brake fluid leaks.
  • Check around the brake calipers and wheel cylinders for any wetness or dripping fluid.
  • If leaks are found, replace the damaged brake lines or components.

4. Brake Booster Testing

• Sub-steps:
  • With the engine off, pump the brake pedal several times to deplete residual vacuum.
  • Hold the pedal down and start the engine; the pedal should drop slightly.
  • If there is no change, the brake booster may be faulty and should be replaced.

5. Brake Master Cylinder Inspection

• Sub-steps:
  • Remove the master cylinder by disconnecting the brake lines and unbolting it from the brake booster.
  • Inspect for internal leaks or damage by checking for fluid seepage.
  • If defective, replace the master cylinder and bleed the brake system.

6. Brake System Bleeding

• Sub-steps:
  • Use a brake bleeder kit to remove air from the brake lines.
  • Start with the wheel farthest from the master cylinder and progress to the nearest.
  • Ensure the brake fluid reservoir does not run dry during the bleeding process.