Many newer BMW cars come with a feature called Dynamic Brake Control or DBC. This is an advanced active safety system, which monitors and adjusts the braking power of each wheel.
By doing so, it improves brake effectiveness, particularly in emergency situations. When the driver needs to stop during an emergency situation, the system applies maximum braking power in a controlled manner in order to stop the car in the minimum distance.
As this system controls the brake application electronically, it can offer useful additional features. One of them is Start-off assistance, which helps the driver to start at the incline without pressing the brake.
If there is a problem within this system, a set of warning lights will alert the driver.
In addition to the DBC malfunction message on the iDrive display, there will be several yellow warning lights on the dashboard and central display.
In most cases, all of these will be related to the brake system.
As a result of DBC issues, Start-off assistance stops will stop work, with Start-off assistance inactive message on the iDrive warning the driver.
Lastly, the driver may notice that the braking feel and performance are different. It is important for the driver to adjust the driving style in such a situation.
- An internal fault within the ABS hydraulic module is the most common cause. In addition to disabling the DBC system, it can also affect both DSC and ABS systems. As this fault is quite frequent, there are many specialists that can repair the module. This is a cheaper option than buying a new one, and more reliable than installing a used module.
- A battery that is going bad and does not hold the charge can cause all sorts of electrical issues. In such a scenario, brake systems like DBC and DBS are first to be affected. Checking the voltage on the battery terminals will reveal its condition. It is a good idea to check the battery terminal for dirt or corrosion, as this can have the same effect as a bad battery.
- Much like the bad battery, a dying alternator can cause various electrical systems to act unusually. DBC and DSC are very sensitive when it comes to voltage, so they are easily affected.
- Steering angle sensor. A piece of important information for this system is the angle of the steering wheel, as it needs to know if the car is turning or going straight. A steering angle sensor provides this data, and if it fails, the DBC system will go off. The wheel misalignment, in some cases, can have the same effect.
- A faulty wheel speed sensor will bring down all brake assist related systems, as they all need information about wheel speed. In practice, rear sensors are more likely to fail. Before replacing the sensor, check the wiring and the connector itself. Lastly, after removing the sensor, check it for damage at the frontal are. If there any scuff marks, the ring is either corroded or bent out of shape. Such a ring must be replaced, as it will damage the new sensor.