why does my Toyota Highlander Fourth Generation (2020-present) braking system feel spongy and go to...

Solution

1. Preparation

• Gather tools: brake fluid, wrench set, brake bleeder kit, OBD-II scanner, and safety equipment (gloves, goggles).
• Ensure the vehicle is parked on a level surface and secured with wheel chocks.

2. Check and Replace Brake Fluid

• Sub-steps:
  1. Open the master cylinder reservoir cap.
  2. If the brake fluid is low, add the recommended type of brake fluid (DOT 3 or DOT 4 as specified in the owner's manual).
  3. If the fluid is contaminated or dark, proceed to flush the brake system.

3. Inspect and Repair Leaks

• Sub-steps:
  1. Inspect all brake lines and hoses for signs of wear or leaks.
  2. If leaks are found, replace the affected hoses or lines.
  3. Check brake calipers for leaks; replace or rebuild if necessary.

4. Bleed the Brake System

• Sub-steps:
  1. Start with the wheel farthest from the master cylinder (right rear), and use a brake bleeder kit.
  2. Have an assistant pump the brake pedal several times and hold it down.
  3. Open the bleeder valve on the brake caliper to allow fluid and air to escape, then close it before the assistant releases the pedal.
  4. Repeat this process for the left rear, right front, and left front, checking fluid levels in the master cylinder frequently.

5. Test and Replace Brake Components (if necessary)

• Sub-steps:
  1. Inspect brake pads and rotors for wear; replace if pads are less than 3mm thick or if rotors are warped.
  2. If the brake booster is faulty (not allowing the pedal to feel firm), replace it as per the service manual.