New Pixhawk 4 Motor issues

Hello everyone,

I’ve been flying with a 3DR PX4 since 2013, and everything worked great. About a year ago I made the mistake of switching to a DJI Naza M, and recently bought a new Pixhawk 4. When I took the helicopter apart two weeks ago, it was a fully functional flying hex. Now that the heli is rebuilt I have been having trouble with one single ESC/motor.

When I power up the helicopter, motors 1-5 beep every 2 seconds, nothing from motor 6. Then after the Pixhawk boots, motors 1-5 make their 4 beeps (4S battery) and then indicate they are ready to go. At this point, motor six starts the beep every 2 seconds, and keeps beeping. I can arm and run up 1-5, but 6 keeps beeping.

I’ve been running these motors and ESCs for roughly 3 years now, without a single issue. I know the 2 second beep means the throttle is out of range, but why would motors 1-5 be within range, and not 6? I have done the ESC calibration, both in QGroundControl and manually. I also wonder why there is such a delay in the booting sequence for motor 6, but 1-5 all boot together? I have also manually set PWM_MIN and PWM_MAX to 900 and 2100 respectively, just in case it was barely off, but that didn’t change anything.

Any ideas you guys might have would be appreciated. Is there a way to see the boot process in real time? A log file that shows the boot process that could maybe shed some light on the delay? With all new wiring, including power and signal, I can’t imagine it’s a bad signal wire. Is there a way to test the signal wire from the PM07 board? I know I could do a resistance test on the wire itself, but like I said, it’s all new wiring and I don’t think it would be a broken wire.

  • Pixhawk 4
  • PM07 V2.2
  • Multistar motors
  • Turnigy Plush 30A ESCs


What version of PX4 are you using?

I actually figured it out, sort of.

Turns out I pinched a wire when assembling, and it was cut. So I got the motor working. Now however, when I try and arm I get the fail safe throttle error message. I try and adjust my pwm_min and pwm_max, and then I get an out of range message. I keep playing with it, I will get it eventually and post here what I find.


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