What is an ABC or Active Body Control System?


The ABC or Active Body Control System is a type of suspension meant to help control your vehicle’s movements to stabilize it through risky maneuvers like taking sharp turns or braking quickly and is sometimes recognized as the “Drive Carefully” light on your Mercedes dash. As you can imagine, it is a pretty important safety feature. If it fails, your entire suspension system fails, and you can no longer drive safely. That is why you need to be informed of the issues that may arise with the Active Body Control system employed before it turns into a problem that can’t be fixed. Let’s look at some of the common problems the system has, why they occur, and prevention.


Common Issues With the ABC System


There are a few things you may notice are happening to your Mercedes-Benz while driving that could be an indicator of ABC System Failure. Other things are much harder to look for, so pay extra careful attention to the things that you can.


“Drive Carefully” Light On


If your “Drive Carefully” warning light comes on, this may be a signal that the control system is failing. The color of the and consistency of the warning light is key. Blue or white light tends to be related to minor issues while the red light is more serious. If any of these lights come on and go off right away, again not a big deal, but if they come on frequently or stay on, serious, and you should not drive your vehicle until you can have it repaired.


Car Sags When Parked


This can be normal and is nothing to worry about. After a few weeks of driving, you will likely notice that your car is sitting a little lower. However, having this problem within a week or less means that your system could be having issues.


The vehicle is Making Whining Noises


If you notice any unusual whining or humming noises, your problem may be with the pulsation dampener in your ABC system. It could also be a lot of other things but in conjunction with any of the other warning signs, this is the most likely cause.


Underlying Causes of ABC System Failure


Hydraulic Fluid Leakage


This is quite a common issue. Several different parts make up the ABC system, so it possible for many places the hydraulic fluid could leak from. When that happens, you may notice that your car will be sagging closer to the ground. In certain instances, this can make your car difficult to drive. The body of your vehicle may drag on the ground, damaging unrelated components to the failing system.


Improperly Sealed Valves


If the valves in the parts of your ABC system are not properly sealed and locked, the hydraulic fluid could leak from them. Note, you may not be able to see the leak or leaking hydraulic fluid. This is where a certified mechanic can help.

Debris Accumulation

The valve block can sometimes get dirty from road debris and if not cleaned and maintained in a while the filter will fail and need to be replaced. 

How to Prevent ABC System Failure


The best prevention is following your Mercedes-Benz factory scheduled maintenance by a certified mechanic who can ensure the components are inspected and maintained correctly. 

Fifth Gear Automotive Can Help 

It may be difficult to find a mechanic other than at a dealership that will be qualified to handle either the maintenance or repair of the ABC System. Fifth Gear can help, we work on most all makes and models and specialize in Mercedes and other European makes. Contact us today to schedule an appointment our technicians are trained and certified to handle most any repair, regardless of the vehicle’s manufacturer, we have you covered.


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Fifth Gear Automotive


We are a family-owned independent automotive repair shop. We have over 100 years of experience with all domestic and import makes and models, specializing in European auto repair. Proudly serving for over 15 years Lewisville, Highland Village, Flower Mound, Lantana, Double Oak and the surrounding communities. We have one goal; Complete Customer Satisfaction on all your auto repairs.

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