Modern vehicles are equipped with many on-board computers to monitor the performance and health of the vehicle's components. When a problem arises, warning lights are illuminated to notify the driver of a potential issue. These warning lights are integrated within the instrument cluster/dash panel. A common warning light that can appear is the ABS warning light for the ABS (Anti-Lock Braking System). Ignoring the warning light can jeopardise your safety on the road and lead to costly repairs. In this article, we’ll discuss the importance of the ABS warning light and what to do when it is illuminated. 

What is the ABS Warning Light for & Why is it Important? 

The purpose of the Anti-Lock Braking System (ABS) is to stop the wheels from locking up during braking. When combined with ESP (Electronic Stability Program), it will reduce the risk of the vehicle losing traction. When there is a problem with the Anti-Lock Braking System, the ABS warning light will be triggered to illuminate. When the warning light is illuminated, it is imperative to have the fault diagnosed by a competent technician using specialist diagnostic equipment to read the ABS fault codes. It’s important to note that whilst the ABS warning light is on, the ABS will be de-activated and extra caution should be taken when driving the vehicle in this condition to and from the repair shop. 

Common Causes of the ABS Warning Light

There are many interconnected components which make up the entire ABS system, it’s important to understand what they are and some of the common causes that can trigger the ABS Warning Light. 

• Wheel Speed Sensors: The wheel speed sensor sends information back to the ABS module, letting it know the rotational speed of the wheel. Some vehicles have a wheel speed sensor for each wheel, whereas other vehicles may have wheel speed sensors on just some of the wheels. When they become faulty, the ABS module cannot identify the speed of that wheel and whether it is in sync with the other wheels. 
• ABS Module Failure: If the ABS module fails, it may be unable to communicate with the other components of the ABS system and/or other modules on the vehicle. This is a critical ABS system failure. 
• Low ABS Fluid Level: Whilst this is a hydraulic issue, low brake fluid can cause issues for the hydraulic valves within the ABS pump. If the valves cannot build pressure or run dry and get stuck due to lack of fluid, this will trigger an internal valve fault to be stored in the ABS module and bring on the warning light.

What To Do When The ABS Warning Light Comes On

Below we’ve compiled some simple-to-follow steps on what to do when your ABS warning light comes on. 

Don’t Panic - Attending to the warning light immediately is important but don’t let it panic you. The vehicle in most cases will still run fine and will just be the Advanced Braking System that will be deactivated. You can in most cases continue driving to your local repair shop to have the fault diagnosed but extra care should be taken when driving in such conditions - leave extra space between other road users and brake earlier to avoid harsh braking.

Check Brake Fluid Level - If the fluid level is low, the warning light can illuminate. Topping this up may resolve the issue but you may still need to have the warning light reset in some cases using diagnostic equipment. 

Get Professional Help - You will need to have a technician connect specialist diagnostic equipment to the vehicle's onboard diagnostic (OBD) system to retrieve the diagnostic fault codes stored within the ABS module. This will help identify the cause of the fault and also reset the light if possible. 

Avoid Unnecessary Driving - The ABS warning light being on is an MOT failure. You should avoid unnecessary driving and try to get the vehicle over to your local repairer as soon as possible to have the fault rectified. 

Avoid Harsh Braking - With the ABS system de-activated, the wheels may lock up under harsh braking conditions. Avoid harsh braking by leaving extra space between yourself and other road users, lowering your speed and braking earlier than usual. 

How To Avoid The ABS Warning Light Coming On

Sometimes it is inevitable that warning lights will come on as vehicles age due to wear and tear of components. However, there are steps you can take to try and minimise the causes. 

Scheduled Inspections - Experienced technicians can often detect potential problems within the ABS system before they escalate to bigger issues. Inspection of the wheel speed sensors, brake fluid level and electrical connections from time to time is a great way to proactively stay ahead. 

Brake Fluid Flush - As the brake fluid and the components in which it travels (pipes + callipers etc) wear down over time, the fluid can become dirty and also contaminated. This can lead to issues potentially within the hydraulic valves of the ABS pump. Flushing the brake fluid system can avoid this potentially expensive issue. 

Regular Maintenance - Servicing the vehicle regularly is very important. Making sure your wheel speed sensors are clear of any debris that may interfere with the contacts and ensuring the brake pads and discs are also in good form, will be a great way to avoid issues in the long term. 

Conclusion

Vehicle owners must be aware of the ABS warning light, its purpose, potential causes for it coming on and also what to do when it does illuminate as well as how to prevent some of the most common causes. Through proactive maintenance, we can ensure to minimise our time off the road with expensive breakdowns and increase our safety on the road.