Siemens Bsm B3: Schematic

This connector handles the digital multiplex communication and low-power trigger signals returning to the dashboard.

The tier level (B2, B3, B4, B5) dictates factory-installed internal relays. A BSM B3 unit features integrated relays for front fog lights (which B2 units often lack) but excludes specific auxiliary relays found in B4 and B5 tiers (such as secondary air injection pumps). siemens bsm b3 schematic

Hidden at the bottom or sides of the unit, these supply high-current systems like the radiator fan, ABS block, and cabin climate blowers. and cabin climate blowers.