If voltage is present at BSI but not at the light, the wire is broken somewhere between the dashboard and the boot.
The diagram reveals that the tail light shares a common ground (e.g., MC50 - chassis earth near the rear bumper). The brake light uses a separate wire but the same ground. Since the brake light works, . The problem is either: wiring diagram peugeot 308
Look up "Rear light cluster" or "Left rear lamp" in the diagram index. Find the component code (e.g., 5520 for left tail lamp). If voltage is present at BSI but not
The is the central fusion box and master computer. You cannot treat the BSI like a classic fuse box. If you probe the BSI incorrectly, you can destroy the unit, leading to a costly replacement and programming. Since the brake light works,
