This is part of the anti spill system. This was feature for the AU market. I don't think the US loaders came with it. 
Basically, as you raise the loader, it won't let you drop whatever it's in the bucket, on top of you and the tractor. It uses a set of cams and linkages on the loader that actuate a limit switch that then turns those solenoids on or off to stop the loader from moving.
View attachment 4327164
And the page from the parts catalogue: 
https://partscatalog.deere.com/jdrc/sidebyside/equipment/299/referrer/navigation/pgId/2563808