Solving the Mystery Wires

Here’s a fact nobody warns you about before you buy geared motors with built-in encoders: the wire colors are not standardized. Six wires come out of each motor bundle, and the harness colors follow no convention you can look up — they’re whatever the factory had on hand that day.

Two of those six wires are the actual motor power pair. The other four feed the encoder, which reports wheel rotation but doesn’t move anything itself. Wire the encoder pins to a motor driver and nothing happens — or worse, something happens inconsistently, which is a much more confusing failure mode.

The fix was low-tech: a multimeter, continuity mode, and a direct test — touch a candidate pair straight to the battery for a fraction of a second and see if the shaft twitches. A few pairs looked electrically plausible (low resistance, connected to each other) without actually being the winding. Only one pair made the wheel spin.

Once both motors’ power pairs were identified and labeled, the wiring into the driver board’s screw terminals was straightforward. Verified with a full battery-powered spin test before trusting it: both wheels turned, on command, for the first time.