I have ArduPlane 3.3 set up on my wing, using elevon mixing. Everything works as expected. Because I am interested in adding yaw control to the wing, I am investigating using split elevons. The problem is that I cannot get the Aux pins to drive a servo.

Setting RC*_FUNCTION to some nonzero value that makes sense (16 or 17 for split elevons, rudder, ground steering, etc), and writing the configuration to the board yields no response. I am powering my elevon servos with an independent UBEC, connecting only the signal pin from the servo to the board (JP1 is not connected). When I am testing the Aux output, I am moving the servo signal pin on the "Output" rail to the appropriate Aux pin. So, this is not a servo power issue, or a bad connection in the signal wire.

Although unused, the voltage between the + and - on the Aux rail is 3.3v. Unfortunately, I do not have a scope to look at the output of the Aux signal pin.

Do I need to do something else besides change RC*_FUNCTION? Is there a "Turn on Aux Output" switch?

I have seen others commenting that the split elevon code does not always work. But, before I can troubleshoot that, I need to get some sort of response from the Aux rail (using split elevons, rudder, or something). 

Thanks!

[As a sidenote, the split elevon if/then section in Attitude passes a float to the Aux output, whereas elsewhere, the Aux output is passed an integer. Removing the implicit casting does not affect the non-operation of the Aux rail in the context of split elevons.]