Connect a 5V supply (USB power bank or lab supply) — Red to Hall power wire, Black to Hall ground wire. Do NOT use 12V — you will destroy the hall sensors.

Probe Hall Power (+5V red wire) and Hall Ground (black wire). You must read 4.8V–5.2V. If you read 0V — the controller is not supplying power to halls. If you read 12V — wiring is wrong.

With 5V applied, probe each Hall signal wire (Yellow, Green, Blue) one at a time with your multimeter in DC voltage mode. Spin the wheel slowly by hand and watch the reading.

If Hall A (Yellow) is stuck — that sensor is dead. Same for B (Green) or C (Blue). A motor with one failed hall sensor will typically run but with severe stuttering, erratic speed, or burning smell from incorrect commutation.

For hub motors: remove axle nuts and split the motor by removing the side cover bolts (typically 6–8 M5 bolts). The hall sensor PCB is mounted on a small board inside the stator.

Standard replacement: SS41 or SS49 Hall effect sensor. Desolder the failed sensor. Install new sensor in same orientation — flat face toward rotor magnets, same polarity. Solder on PCB pads. Test before reassembling.

After reassembly, the phase-hall combination may need to be re-identified. There are 6 phase wire combinations × 6 hall wire combinations = 36 possible combos. Use your controller's auto-detect function or test manually at low throttle until smooth forward rotation is confirmed.

Remove wheel from dropouts. Disconnect all phase and hall wires at connectors — do not pull on the wires themselves. Label each connector with tape if colour coding is unclear.

Deflate and remove tire, tube, and rim tape. The motor cover bolts are typically under the spokes — you need clear access to the bolt circle on the side cover.

Most hub motors have 6–8 bolts (M4 or M5) in a circle on the non-drive side cover. Remove all bolts and keep them — they are all the same length typically. Set the motor flat on a clean surface.

The rotor (outer shell with spokes) is held to the stator by the bearings. Gently pry the cover off using plastic trim tools — NOT screwdrivers (they scratch and can damage the stator). The magnets are very strong — the cover will snap back if released.

The hall sensor board is a small PCB mounted on the stator end, facing the rotor magnets. It will have 5 wires running out through the axle (red, black, yellow, green, blue). Mark its position with a permanent marker before removal — the angular position matters.

Typically held with 2 small screws or epoxy. If glued, carefully cut the epoxy with a thin blade. Desolder the 3 hall sensor ICs from the PCB. Note the orientation — flat face of sensor must face the magnets.

Solder new SS41 (or equivalent) sensors in same positions. Reinstall board in exact same angular position. Reassemble cover. Re-spoke if rim was removed. Reconnect all wires and perform phase-hall combination test before full power test.