Grinding Noise When Braking in a 2020 Toyota Highlander

Possible Causes

1. Worn brake pads.
2. Damaged rotors.
3. Debris caught between the pad and rotor.
4. Lack of lubrication on brake components.
5. Faulty calipers.

Step 1: Visual Inspection

• Tools Required: Jack, jack stands, lug wrench, flashlight.
• Procedure:
  1. Safety First: Ensure the vehicle is on a flat surface and engage the parking brake.
  2. Loosen the lug nuts on the front wheels slightly while the vehicle is still on the ground.
  3. Lift the front of the vehicle using a jack and secure it on jack stands.
  4. Remove the front wheels to access the brake components.
  5. Inspect the brake pads for wear. If the pad thickness is less than 3mm, they should be replaced.
  6. Check the rotors for grooves, scoring, or rust buildup.
  7. Look for any debris lodged between the pad and rotor.
  8. Inspect calipers for any signs of leaks or damage.

Step 2: Brake Pad and Rotor Assessment

• Tools Required: Caliper tool (if necessary), micrometer (for rotor thickness), brake cleaner.
• Procedure:
  1. Measure the thickness of the rotors using a micrometer. Minimum thickness specifications can usually be found in the service manual (typically around 28mm for front rotors).
  2. If the rotors are below the minimum thickness, they will need to be replaced.
  3. Clean the rotors with brake cleaner to remove any contaminants.

Step 3: Caliper Function Test

• Tools Required: Brake caliper tool, C-clamp.
• Procedure:
  1. With the brake pads removed, push the caliper piston back using a C-clamp or brake caliper tool.
  2. Ensure the piston moves smoothly without sticking.
  3. Inspect the caliper slides for any rust or corrosion, which can affect caliper movement.

Repair Instructions

Step 1: Replace Worn Brake Pads

• Tools Required: Socket set, torque wrench, brake grease.
• Procedure:
  1. Remove the old brake pads from the caliper bracket.
  2. Install new brake pads, ensuring they are positioned correctly in the caliper bracket.
  3. Apply brake grease to the backing plates of the new pads to prevent noise.

Step 2: Resurface or Replace Rotors

• Tools Required: Rotor resurfacing machine (if resurfacing), new rotors (if replacing).
• Procedure:
  1. If rotors are within spec, they can be resurfaced; otherwise, replace with new rotors.
  2. Install the new or resurfaced rotors onto the hub, ensuring they are seated properly.

Step 3: Reassemble Brake Components

• Tools Required: Torque wrench.
• Procedure:
  1. Reinstall the caliper over the new pads and rotor.
  2. Torque the caliper bolts to the manufacturer's specifications (usually around 80 ft-lbs).
  3. Reinstall the wheel and lug nuts, and torque the lug nuts in a crisscross pattern to the specified torque (typically around 76 ft-lbs).

Step 4: Test Drive

• Procedure:
  1. Lower the vehicle back to the ground.
  2. Pump the brake pedal a few times to seat the pads against the rotors.
  3. Test drive the vehicle at low speeds to ensure the grinding noise is gone and brakes are functioning correctly.

Conclusion

If the grinding noise persists after replacing the brake pads and rotors, further inspection may be required, including checking brake lines, fluid levels, and ABS components. Always consult the vehicle's service manual for specific torque specifications and procedures. If you're unsure or uncomfortable performing these tasks, seek assistance from a qualified automotive technician.