Siemens Bsm B3 Schematic
Disconnect the harness and measure the ohm value of the NTC sensor across Pin 7 and Pin 8. Compare the value to standard temperature-resistance charts.
This public link is valid for 7 days and shares a thread, including any personal information you added. This link or copies made by others cannot be deleted. If you share with third parties, their policies apply. Can’t copy the link right now. Try again later.
Often features a fuse (e.g., ) for the catalyst air pump on petrol engines.
Using the schematic, find the pin for the fuel pump and check if it receives 12V when cranking. 5. Replacing or Repairing the BSM B3
Measure voltage across Pin 1 (Terminal 30) and Pin 3 (Terminal 31). It must match battery voltage. siemens bsm b3 schematic
| Manufacturer | Primary Part Number | Additional/Alternative Codes | Supported Vehicle Examples (Check Specific Fitment) | | :--- | :--- | :--- | :--- | | | 9643498880 | T118470003, 6500Y3 | Citroën Berlingo, C2, C3, Pluriel, C5, Peugeot Partner | | Siemens | 9650618480 | 6500Y3, 6500Y1 | Citroën C5, Xsara, Xsara Picasso, Peugeot 307 | | Delphi | 9646405280 | 6500Y1, 6500Y3 | Citroën Xsara, C3, Peugeot 307 | | Delphi | 9643538080 | — | Multiple Citroën & Peugeot models |
The unit splits its logic into two clear halves:
The stamped on your module's plastic casing
: It acts as an interface between the passenger compartment (BSI) and engine components, housing multiple fuses and heavy-duty relays. Disconnect the harness and measure the ohm value
: It is generally interchangeable with higher versions like the B5, sharing the same pinout and core management system.
: Locate the failed relay pin group on the schematic path, desolder it, and install a matching automotive micro-relay (typically manufactured by Tyco or NEC).
If you have confirmed a BSM B3 failure and have an exact matching replacement unit, you can perform the swap yourself using basic tools. for a like-for-like BSM swap on these vehicles.
The schematic for a BSM B3 switch is straightforward, as it is an electromechanical device. However, the internal architecture is designed for high precision. This link or copies made by others cannot be deleted
The BSM B3 module consolidates multiple electrical functions into a single unit to simplify vehicle wiring. Key systems managed by this unit include: autotech24.eu
Houses various fuses designed to protect both engine-specific and general body electronics.
⚠️ Forum discussions reveal that while the physical shape may be the same, a BSM B3 from a different car may not function correctly in yours. For example, one user found their car would start after swapping in a Siemens unit, but the headlights and other systems would not work. This is often due to differences in how the vehicle communicates over its network (e.g., CAN vs. VAN protocols) and the specific configuration of options (like having fog lights or not). Therefore, matching the exact part number is mandatory, and some modules may require coding using a professional diagnostic tool.
The system architecture is split into two specialized physical zones:
When wiring the replacement system, retain the original -X terminal numbering scheme where possible to simplify future maintenance for the on-site engineering team.
