Owner's Manual for the vehicle. With a quick reference ... - E38.org

126nAntilock Brake System (ABS)
In the event of a fault
If the ABS warning lamp in the
instrument cluster comes on, refer
to page 21. The brake system
then reverts to conventional
operation as on vehicles without
ABS. However, have the brake
system checked by your BMW center
as soon as possible. To prevent undetected
defects and cumulative faults
from adversely affecting the brake system,
refer any problems to your authorized
BMW center at the earliest opportunity.
Disc brakes
Disc brakes furnish optimum deceleration
and braking control and greater
fade resistance under heavy use.
When the vehicle is driven only occasionally,
during extended periods when
the vehicle is not used at all, and in operating
conditions where brake applications
are less frequent, there is an increased
tendency for corrosion of the
rotors and accumulation of contamination
on the brake pads. This occurs because
the minimal pressure which must
be exerted by the pads to clean the rotors
by brake applications is not
reached.
If the brake rotors are corroded, they
will tend to respond to braking with a
pulsating effect which even extended
application will fail to cure.
We recommend the use of original
BMW brake pads and components,
otherwise driving safety can be
impaired.