SZL: Steering column switch cluster

The steering column switch cluster is a mechanical and electrical interface from the steering wheel to the vehicle. The steering column switch cluster has a fixed mechanical connection to the steering column. Over and above this purely mechanical connection, the steering column switch cluster is electrically connected via bus systems or directly to components. Depending on the series, the steering column switch cluster may be a control unit (SZL control unit) or not.

• E.g. F01, F10: The steering column switch cluster (SZL) is a control unit

  A signal wire conveys the button signal from the air horn button to the steering column switch cluster (SZL). The steering column switch cluster (SZL) processes the button signal and sends the request signal as a message to the FlexRay. The steering column switch cluster (SZL) is connected through the FlexRay to the central gateway module (ZGM).

• E.g. F15, F25, F20, F30: The steering column switch cluster is not a control unit.

  A signal wire conveys the button signal from the air horn button to the steering column switch cluster. The steering column switch cluster processes the button signal and sends the request signal as a message to the LIN bus.

  Depending on the series, the steering column switch cluster is connected through two local interconnect network buses to one of the following control units:

  • Front Electronic Module (FEM), e.g. F30
  • Junction Box Electronics (JBE), e.g. F25
  • Body Domain Controller (BDC), e.g. F15

The following graphic shows an example steering column switch cluster (front) on an F01. The version of the steering-column switch cluster depends on the options fitted.

Fig 1: Steering Column Lever, Turn Indicator/High-Beam Switch

Courtesy of BMW OF NORTH AMERICA, INC.