APM2.6 & uBlox GPS problem (power light off)

Hi All,

I am having trouble getting my uBlox GPS + Mag (Genuine 3DR) to connect to my APM2.6 (Genuine 3DR).

When connecting the Mag cable only the Power LED (red) is on (solid). When both cables connected (or just GPS) the Power LED turns off. Blue light never turns on in any case. I checked the conductivity of both cables and found ok. Checked each cable for cross connected wires and found none.

Voltage on I2C port is 3.3V and on GPS post is 5.03V. I tried powering the APM with just USB, just Power module and both.

On the test terminal I get “Compass initialisation failed!” and a stream of dot’s when testing gps.

If anyone could suggest some likely causes or fixes that would be greatly appreciated.


Hi Andrew,

There must be some short circuit or something wrong with the ublox GPS side, since it should turn on the PWR led in solid red when the GPS cable is connected. Even whey you have a solid red by connecting the mag to the APM it requires the internal 5V from the GPS side to work, otherwise you will get the compass initialization error.

I don’t suspect on the APM since you are getting the 5V in the GPS port and the 3.3V in the I2C port.

You should send an email to help@3drobotics.com for further assistance.