From the time when vehicles were first manufactured to date, a lot of changes, in terms of technologies and performance, have occurred.

This is largely because there are so many competing companies all over the world which has led to the successive production of vehicles of quality, incorporating new technologies that ensure comfort and safety.

One of the technologies that were incorporated into vehicles in the last 30 years or so is the anti-lock braking system, commonly known as the ABS.

Friction between the tyres and the road is so essential for all aspects of the vehicle’s control. But many a time on applying the brakes, they may lock up all the wheels, making the driver lose control and send the vehicle into a dangerous skid.

This can happen even with the most careful driver, especially during an emergency braking or when the road surface is wet or slippery. Anti-lock braking systems are now fitted to most vehicles so as to help drivers maintain directional control while decreasing the stopping distance.

Vehicles these days have onboard computers/electronic control units (ECUs) which we may safely call the brains of a vehicle. This unit is fed with information inputs, or signals, from each wheel, information such as whether the wheel is revolving and at what speed.

All this is collected by sensors and fed into the ECU and in return, the ECU outputs continuous instructions to the baking unit. Based on the input signals from the wheel sensors, the ABS system’s ECU knows the speed of each wheel, so when the brakes are applied, the wheels, and hence the vehicle, start to slow down.

The ECU monitors each of the wheels’ speeds and in case it is about to lock, then the ECU reduces the braking pressure for that wheel unit the tyre gains grip once again.

This process of sensing and reacting happens so rapidly that it may not be noticed by a vehicle’s occupants. Now, when the ABS system shows signs of failure, a warning light will appear on  the vehicle’s dashboard. And these are some of the reasons the ABS may fail to work:

It often indicates that one of the wheel speed sensors has a problem/is faulty. This means that it cannot effectively communicate a fault to the ECU, and because of this, the light will come on.

An ABS warning light may also indicate the loss of power-assist, if the vehicle’s ABS system relies on an electric pump and the pressure accumulator pump, rather than the conventional vacuum booster.

If both the ABS and brake warning lights come on, yet the power assist is present, then the brake fluid level could be too low and there is loss in one of the brake circuits.

In most cases, the wheels are fitted with rings on their driving shafts which the wheel sensor operates hand-in-hand with. Most mechanics, while replacing the drive shafts, tend to disregard the rings. This means the sensors cannot work effectively and may trigger off the ABS light.

Because many vehicles have very low ground clearance, the cables connecting the ABS system underneath the vehicle often break, most especially when one drives through rough terrain, although they can also break after wearing out, or when a mechanic is working around that particular area in the vehicle.

Lastly, a vehicle showing an ABS warning light doesn’t mean it will not brake. However, that is how it was designed to operate for it to work maximally. This means as soon as the ABS light comes on, make sure you immediately take it to a professional mechanic. 

Source: The Observer