Electrical Reference
BMW
Common wire colors, fuse box locations, and relay tap points for BMW motorcycles. Always verify with a multimeter before making connections.
Common Wire Colors
These are typical colors across recent BMW models. Colors can vary between model years — always verify with a multimeter.
| Color | Function |
|---|---|
| BN | Ground (chassis) |
| R | Battery positive (always hot) |
| GN/BK | Ignition accessory |
Fuse Box
BMW uses CAN bus extensively — avoid splicing into CAN wires. Fuse box location varies by model. R1250GS: under the seat. F-series: behind the side panel. Use only the auxiliary power socket or dedicated accessory connector.
Relay Tap Points
- ✓BMW strongly recommends using the factory accessory plug or auxiliary power socket for 12V
- ✓Avoid tapping signal wires — BMW CAN bus controls most functions
- ✓For horn/light relay taps, consult the model-specific wiring diagram
- ✓Key switch: use the accessory power circuit that switches with ignition
Notes
- •BMW CAN bus systems make direct wire tapping risky — use accessory connectors
- •GS and RT models have good mounting space and accessory support
- •Consider using BMW's factory accessory plug for clean power connection
- •Relay wiring may be more complex on BMWs — consult a BMW specialist if unsure