ABS Systems on BMW models produced after 2007 are generally very reliable but if you have a solid 'Brake Failure' warning light there are a couple of posible causes.

Sometimes an ABS fault could be as simple as incorrect wheel fitment, Others its a simple ABS Sensor failure but overall they're a very reliable component.

The most common being caused by poor connection to the pump motor. Generally caused by lack of use (of the ABS, not the motorcycle) the brushes inside the ABS pump motor become seized. We can rectify this fault by removing the ABS pump, Servicing + modifying the motor and reinstalling it.