ok so i happened to be handed a set of au central locking units from my mates garage clean out. is there a way i can test each unit to see if it works and so i can hopefully sell on? dont want to sell dodgy stuff if i can. dont have an au to bolt into to try them out or i would. any suggestions anyone?

They commonly break the plastic gear/shaft thingy inside. Just pull the cover off each one and inspect - it's a little fiddly to get it back together, but once you've done one, it's easy.

Alternatively you could just power each one up off a car battery - if it continually whirs it's stuffed.