Regulates incoming voltage to power internal logic and peripheral devices.
The ( Boîtier de Servitude Moteur ) acts as the gateway between the engine bay electronics and the interior cabin's BSI ( Boîtier de Servitude Habitacle ).
: Populated by non-serviceable components, including heavy-duty printed relays soldered directly to the board and high-current "Maxi-fuses" positioned on the block underside. siemens bsm b3 schematic
Relays (often soldered), Maxi-fuses, and standard blade fuses Typical Failure Points
The (Boîtier de Servitude Moteur) is an engine bay fuse box and electronic control module found primarily in PSA Group vehicles, including Peugeot and Citroën . This unit acts as a gateway between the engine compartment’s high-power components and the cabin's primary computer, the BSI (Boîtier de Servitude Intelligent). Understanding the Siemens BSM B3 schematic , internal component layout, and common failure points is critical for automotive diagnostics and electronic repair. System Overview & Architecture Regulates incoming voltage to power internal logic and
Often features a fuse (e.g., ) for the catalyst air pump on petrol engines.
Control inputs for sensors, coils, and injectors. System Overview & Architecture Often features a fuse (e
Siemens BSM B3 is an engine compartment fuse and relay box (Boîtier de Servitude Moteur) primarily used in PSA Group vehicles like the Peugeot 206 Citroën C3
The stamped on your module's plastic casing
The schematic of a BSM B3 controller is divided into four primary functional zones:
The BSM B3 is known for being difficult to repair because the connectors are often soldered directly through the plastic housing into the PCB. Faulty units typically cause intermittent electrical failures in lighting, dashboard warnings, or engine starting issues. While the BSM B3 is often considered "plug and play" with the more complete B5 module due to identical pinouts, some vehicle configurations may require the specific B3 original logic to function correctly.