What Are Brake Wear Indicators And How Do They Work?
The modern vehicle has many electronic modules that allow you to safely rely on the warning systems that notify you of a potential failure. The same is true for brake pads. There are wear indicators on the brake pad itself that sense brake pad wear and signal the ECU, which informs the driver in the dash or infotainment system about the brake pad condition. Some less advanced vehicles simply show a warning light when the brake pads need replacement. There may also be a noise generated that warns the driver if the brake pads are completely worn and need urgent replacement.
What Are The Types Of Brake Wear Indicators?
Conventional Brake Wear Indicators
The first type of brake pad wear indicators were metal pieces that were either part of the brake pad backing plate or the shim. As the pad wore down to about 3.2 to 4 mm of thickness, the metal piece came into contact with the brake rotor when the brakes were applied. This contact produced a high-pitched noise, alerting the driver to the need for brake pad replacement. The disadvantage of this system was that the driver ignored the warning sign because he assumed the noise would go away.
Electronic Brake Wear Indicators
Then came electronic brake wear indicators, which were single-stage sensors that worked on a simple resistance loop. As the brake wore down to a certain point, the sensor made contact with the rotor, causing the plastic connection to break and the resistance to increase, resulting in a warning light on the dashboard.
Modern Brake Wear Indicators
The most modern type of sensors are two-stage sensors that work similarly to the previous type but can also sense the brake pad thickness at 50%. This data is then used to determine how long the brake pads will last by analyzing the condition of the brake pads using other parameters such as brake disc temperature, brake engagement time, brake pressure, wheel speed, and mileage. The ECU then displays the gradual wear of the brake pads in the infotainment system until the final stage of the sensor is completed and the warning light indicates that brake servicing is required.
The issue with electronic sensors is that they need to be replaced every time the pads are replaced, as they break after a single use. Some manufacturers include replacement brake wear sensors with new brake pads. These sensors are inexpensive and make it easier for the driver to replace worn brake pads.
Why Is The Brake Warning Light On?
The brake warning lights can come on due to several reasons associated with brake components malfunctioning. Here are some common causes for brake lights to come on:
An engaged Parking or Emergency Brake
Low Brake Fluid Levels
ABS Malfunction
Burnt Out Brake Light(s)
Worn-Out Brake Pads
One of the most common reasons for the brake light to come on is due to worn out brake pads. Both mechanical and electronic brake wear sensors are designed to alert the driver to replace the brake pads. However, this warning is often disregarded until brake performance severely plummets. So you need to be mindful of the reasons for brake wear failure and replace the brake pads whenever you see the brake warning light. You may notice the following symptoms when you need new brake pads:
A high-pitched squeaking or squealing sound when pressing on the brake pedal
Longer than usual stopping distances
Unusual "softness" in the brake pedal
A vibration in your steering wheel while braking
Loss of grip when braking