Knowledge base
Controller
Possible causes
- Internal controller fault (power stage, supply)
- Over-current or short on the motor/phase side
- Firmware/configuration error
Safe test steps
- Burnt smell, discoloration, water traces on the controller.
- Rule out motor, Hall, throttle and brake signal before replacing the controller.
Workshop reference values
- No general documented measurement value – manufacturer service documentation required.
Repair approach
- Fit a controller of the same voltage/current class and compatible protocol.
Tools needed
- Digital multimeter (CAT III, fused inputs)
- Basic hand tools, insulated screwdrivers
- Manufacturer dealer diagnostic tool/software (if available)
Safety
- Do not reconnect a controller suspected of a short to the battery.
Related verified fault codes
| Code | Meaning | Component | Reliability |
|---|---|---|---|
| Bafang 35 | 15 V detection circuit fault | Controller | Per manufacturer documentation |
| Bafang 37 | WDT (watchdog) circuit fault | Controller | Per manufacturer documentation |
| KT (Kunteng) 06 | Motor or controller short-circuit abnormality (KT-LCD3 manual) | Controller | Widely published – may differ by model/firmware |
| Xiaomi 28 | Controller power stage (high-side MOSFET) fault | Controller | Widely published – may differ by model/firmware |
| Xiaomi 29 | Controller power stage (low-side MOSFET) fault | Controller | Widely published – may differ by model/firmware |
| Segway-Ninebot 28 | Controller power stage (high-side MOSFET) fault | Controller | Widely published – may differ by model/firmware |
| Segway-Ninebot 29 | Controller power stage (low-side MOSFET) fault | Controller | Widely published – may differ by model/firmware |