Pixhawk relay to control nav lights

Trying to get Pixhawk to control a relay. Using channel 8 on radio. Relay power in is connected to battery. Relay power out is connected to a light. The signal cable from relay is plugged into aux out 5 on Pixhawk. This cable has black, red, and signal. The switch on the transmitter does not turn the light on. Does Pixhawk need only the signal wire? Have we missed some other settings? In config/tuning we have first relay pin set to Pixhawk aux 5. We have ch8 opt set to relay on/off.

after day two of messing around with this, here is what we have:

1.) Official 3DR email support says “all we have is what the wiki says”. Not helpful
2.) I now powered the servo rail with 5v bec. Now I can get the relay to turn on. Will NOT turn off. Looks like a one shot deal. Turn on once, stay on until you pull the plug

Seems pretty silly to me. Why call it aux out? Why call it a relay? If there is no other info available other than a wiki that just says “this is a relay pin”, its a bit disappointing. Pixhawk was supposed to be a bit more sophisticated than that.

Channel 8 on the radio is scrolling between 900 and 2000 for on off. In the off position (900), the relay is off. Turn on and the radio goes to 2000 and turns on the relay. Flick the switch back to off (900) and the relay says on.

Don’t get your underwear in a ball. I assure you it does work and rather nicely at that.

Here is a video of a 12v LED strip being turned on with an N-Channel MOSFET as the relay on pin 5.

Here is a picture of the Pixhawk. The bottom pin is the relay pin that switches between 0 and 3.3v. It however is not able to source a lot of power so you may need to power a relay device to use it. In my case a MOSFET.

Also you need to set what relay pin you want to use with what channel. I used channel 8. Follow this page to set that up.

I did not use the servo rail at all as I needed more than 5v.