Inconsistent startups

I’m new to all of this.

I’m setting up a Pixhawk with APMPlane 3.0.3, Ublox GPS, 3DR power module + 3S lipo, servo rail powered from ESC BEC. I’m using a traditional JR PWM radio via the 3DR PPM encoder.

I get different (big) LED indications for different startups. On “good” starts I have servo control from the radio and can connect Mission Planner OK.

On “bad” starts I have servo control from the radio but cannot connect MP, it times out.

A good start led sequence is: White, Yellow flash, Red/Blue flash. Yellow double flash, Yellow single flash, solid Blue then single low tone.

On a bad start the led sequence is: White, Yellow flash, Red/Blue flash, solid Red.

I may do two or three bad starts before I get a good start. I’ve also noticed that the Pixhawk leds are much brighter and that startup seems to take longer when powered from the PM. They are dimmer and the startup is faster when powered from USB. Plugging in the USB after a power up from PM also makes the leds dim.

I can’t find any reference to what the Red led is indicating (or to what the single low tone means).

So, is this normal behavior or should I be checking something in my setups?



I’ve not been able to isolate any particular cause of this (it’s a 3DR Pixhawk, by the way). What I do see is that if the start up ends with a solid red led then I have manual control mode only from the radio, no auto modes will engage.

I’ve just switched to my new Taranis and X8R radio combo but still see the same start symptoms.


Hi Dave.

I am also experiencing this issue. It first happened to me two days ago while swapping packs. A power cycle got it to boot properly. It happened twice yesterday.

I have not changed any hardware since I upgraded to 3.0.3 a few weeks ago.

I don’t think the change of radio would cause a failed boot.

  • Muhammad.