General information

Microphone and connection of the microphone 

Depending on the vehicle equipment, the vehicle equipment is connected to different control modules. The microphone signals are then transferred across the MOST bus to the other control modules.

If only a ULF-SBX-H interface box High is installed, the vehicle microphone is connected to the ULF-SBX-H. The electrical power supply and diagnosis of the vehicle microphone are handled by the ULF-SBX-H.

Fig 1: Microphone - Circuit Diagram

Courtesy of BMW OF NORTH AMERICA, INC.

If there is a parallel installation of Telematic Control Unit (TCU) and ULF-SBX-H in the vehicle, the vehicle microphone is connected to the TCU. All telephone functions are implemented via the TCU. The ULF-SBX-H provides the voice recognition system as well as other functions (depending on vehicle equipment). Diagnosis of the vehicle microphone is implemented within the framework diagnosis of the TCU.

Fig 2: TCU - Circuit Diagram

Courtesy of BMW OF NORTH AMERICA, INC.

If a Car Communication Computer (CCC) is fitted in the vehicle, voice control is not provided by the ULF-SBX-H. In this case, use the diagnosis for the CCC in the event of problems with the voice recognition system. If fitted, the ULF-SBX-H only provides the functions for the audio player or telephony depending on the equipment version.

Fig 3: CCC - Circuit Diagram

Courtesy of BMW OF NORTH AMERICA, INC.