The ECU constantly monitors the road speed of each wheel; if it detects a wheel rotating significantly slower than the others, it actuates the valves to reduce hydraulic pressure to the brake at the affected wheel,this results in reducing the braking force on that wheel.The wheel then turns faster. Conversely, if the ECU detects a wheel turning significantly faster than the others, brake hydraulic pressure to the wheel is increased so the braking force is reapplied, slowing down the wheel. This process is repeated continuously and can be detected by the driver via brake pedal pulsation. Some anti-lock system can apply or release braking pressure 16 times per second.This is the electro mechanical version of cadance braking.
If a fault develops in any part of the ABS, a warning light will usually be illuminated on the vehicle instrument panel, and the ABS will be disabled until the fault is repaired and the system reset.Faults generally tend to be sensor related, either the wheel sensor itself or a build up of corrosion on or around the hub or abs ring.
Using specific diagnostic equipment allows rps mobile car mechanic to quickly identify the problem by reading the ecu, repair and clear the fault codes which will switch off the abs warning light and reinstate the system to full functionality.
Many modern cars also have traction controll, electronic stability ecu’s which depend on the ABS functioning correctly.