# ESC won't calibrate

Source: https://forum.modalai.com/topic/778/esc-won-t-calibrate
Category: ESCs, Sensors and Accessories (https://forum.modalai.com/category/15/escs-sensors-and-accessories)
Tags: esc
Posted: 2022-03-02 00:10:07 UTC by Jimk_Aero
Replies: 2 · Views: 1336

## Jimk_Aero · 2022-03-02 00:10:07 UTC

Setting up a flight core on a 550 quad that was previously successfully flown with a pixhawk cube.  Everything is working fairly well, except one of my four motors won't spin.  I have used the Python tool several times in an effort to recalibrate that last ESC which I know worked previously, but now it won't.  Can you offer any ideas on how to proceed?  Thanks, Jim.

## Reply by modaltb (ModalAI staff) · 2022-03-02 00:57:04 UTC

Hi @Jimk_Aero ,

Have you confirmed that you can spin the motor 'manually'?

If you are comfortable using the MAVLink shell from QGroundControl, you could try to use the `pwm` command at the command line to try to spin the motor manually.

https://dev.px4.io/master/en/middleware/modules_command.html#pwm

If that doesn't work than I'd start to look at the wiring next.

## Reply by Jimk_Aero · 2022-03-02 19:30:39 UTC

Thanks for your suggestions.  I ran the pwm test command in the MavLink console and confirmed all motors except the suspect one so looks like I'm going to replace an ESC.  I do appreciate your guidance.