Finding start BHAV

I'm working on a request-inspired project. I want to create a custom sprinkler that you have to manually turn on, and that actually increases crop quality (because really, since when do plants care if it's a sprinkler or a person watering them?). As usual finding the code is easy enough, but there's a lot in this project I haven't dealt with before so it's a slow process.

I'm having trouble locating where the sprinkler object is calling in the global BHAVs so that it starts watering. There are only 4 BHAVs in the sprinkler (play animation, add to water bill, and two about placement of the object). Since it's automatic there is no pie menu function to look at, and the things listed in object functions aren't leading me anywhere. Any advice on where I should be looking to find where it's calling the global things so I can start unravelling how it works?