Description
Overview
Siemens BSM B4 engine fuse and relay box for Citroën and Peugeot vehicles. This is a used unit bearing part code 9650618380 (including 9650618380-00, T118470004, PSA 6500.Y3 / 6500.Y1). It serves as a direct replacement when the original BSM fails, preserving factory compatibility when the BSM type and part numbers match; no vehicle coding is normally required.
Function And Common Faults
The BSM (Boîtier de Servitude Moteur) distributes and switches high-current circuits in the engine bay. Typical circuits controlled include the fuel pump, cooling fans, wipers, horn and exterior lighting. On older PSA models the BSM is a frequent failure point. Common symptoms of a faulty unit are unexpected fan activation, fuel pump outages preventing engine start, non-functioning wipers or lights, and repeated fuse failures. Replacing the faulty BSM with a matching unit usually restores proper operation.
Compatibility
Compatible models include Citroën C2, C3, C5, C8, Berlingo, Xsara, Xsara Picasso and Peugeot 206, 307, 406, Partner. Note that PSA used several BSM variants depending on equipment level; always compare the BSM B4 marking and the exact part numbers before ordering. Incorrect variants can differ in fuse ratings or relay population.
Installation And Replacement Tips
The BSM B4 is located in the engine bay near the battery. Before starting work disconnect the negative battery terminal. Release the fuse holders, unplug the colour-coded multi-pin connectors and unclip the unit from its bracket. Fit the replacement by reversing the steps: secure the unit in the holder, firmly attach all connectors and reinstall fuses according to the lid chart. The BSM is not paired to a VIN or immobiliser on these PSA models, so no coding is required when the correct type and part numbers match.
Condition And Notes
As a used part, cosmetic issues such as damaged plastic mounting tabs may be present; these usually do not affect electrical function when the unit is correctly installed in the fuse box holder. Ensure that the internal fuse fields and relay positions correspond to the BSM B4 specification before installation.
Technical Information
- Manufacturer: Siemens
- Model: BSM B4 (Engine Fuse And Relay Box, mounted near battery)
- Product Codes: 9650618380, 9650618380-00, T118470004, T118470004 L
- Other Numbers: PSA 6500.Y3, 6500.Y1
Important: Always compare the BSM B4 type and all codes stamped on the label (9650618380 / 9650618380-00 / T118470004 / 6500.Y3 / 6500.Y1) with your original unit. If you are uncertain, use the part number from your old BSM and a PSA VIN parts decoder to confirm the correct variant.
