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DC/DC converter

Due to the considerably more frequent occurrence of starting operations, the electrical load that occurs often leads to voltage dips in the vehicle electrical system. To ensure a consistent voltage supply to specific electrical components that are especially sensitive to voltage variations, a DC-DC converter is installed on vehicles with MSA. The DC/DC converter supplies both "Terminal 30" relays with a constant voltage that even remains consistent during engine starts.

Fig 1: Identifying DC/DC Converter And Plug Connection
G09841217Courtesy of BMW OF NORTH AMERICA, INC.
Item Explanation
1 E-box
2 DC/DC converter
3 Plug connection

The DC/DC converter is fitted in the electronics box in the engine compartment.

The electronics use the input voltage and terminal 50 measuring cables to determine whether or not the voltage supply of the output is supplied via the bypass or via the DC/DC converter. In bypass mode, the vehicle voltage is not supplied via the DC/DC converter, but is transferred directly to the outputs. In the booster phase, the vehicle voltage is adapted.