WARNING: This page is about a different car, the 2002 BMW M Roadster, 2002 BMW M Coupe, 2001 BMW M Roadster, and 2001 BMW M Coupe. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: ABS Wiring Diagram
Courtesy of BMW OF NORTH AMERICA, INC.
NOTE:
For troubleshooting pin assignment, refer to Vehicle Electric/Electronic Test Plan.