I have my APM connected to the Mega IMU shield but I am struggling with the relay...
I switched the APM to CLI mode and entered the test mode, I then selected "relay" which switches the realy on and off every few seconds.
The relay on my shield is however not responding.... I measured the voltage on the relay coil and it only receives 0.06V when the coil is activated (and 0 when not) I traced this through the schematic and board to be connected to pin 47 and all seems fine with the tracks, measuring the interface pin on the APM board gives the same results
I did wonder if the coil input was shorted to ground somewhere but the resistance measures about 2.8K which would be about right for a relay coil...
Pulling my hair out here... any help would be appreciated.