This is a Y-adapter for the sensor cable connection to sensored brushless motors commonly found in electric radio controlled (RC) cars. It serves two purposes. The first is for use the FDR Checker (which measures the mechanical drive ratio of these cars), but it can also be used standalone to check the health of the sensors in a brushless motor. There are three LEDs which indicate when the sensor is triggered by the magnetic field of the rotor. In a healthy motor (or sensor assembly) the LEDs will light in sequence as the rotor is turned. If all or none of the LEDs light, then there is a fault in either the motor or the cable connecting it to the ESC (electronic speed control).

With many modern motor designs, debris and moisture can make their way into the internals of the motor and have been known to affect sensor assembly performance. Physical damage to the sensors can also arise. Failing sensors can result in lower motor performance, particularly from a standing start.

As mentioned above, this was originally developed to support the usage of the FDR Checker, but has subsequently proved useful in diagnosing sensor issues without using the checker.

This is a simple, lightweight addition to your pit box, helping you troubleshoot issues on race day or back on the bench.

Note that you'll need an extra sensor cable to wire it all up - this cable is not included.