Error 3 on a Trotter 685 and 900T Treadmill

Probable Cause

1. This could be an issue with the speed sensor or speed sensor cable if the belt moves slightly before the error occurs.
2. If the belt doesn’t move this could be an issue with the motor or motor controller.

Corrective Action

1. If the belt moved prior to the error, check the speed sensor gap and cable connection. Inspect cable for crimped or broken wires and ensure a good connection to the board. Speed sensor gap should be .015" - .040" (.0381 - .1016 cm). Speed sensor should provide a reading of 1K – 1.4K ohms. If the speed sensor provides proper ohms, can the speed sensor magnet pick up a 9/16" wrench? If not, replace the speed sensor.
2. If the belt doesn't move when the motor is commanded to start, confirm the drive motor is receiving power from the motor controller. If not, then the motor controller should be replaced. If the motor is receiving power and doesn't turn, the motor should be replaced.