gutting electrical -- what's under the battery box

So I decided to do something very bad. I decided to make something a bit more minimalist and am removing the pieces of electric that I don't understand or won't use. Most of the parts I know or understand straight away. There is one that is really confusing me, though.

Under the battery box, I had two components. One was the regulator/rectifier. The other is a smaller squared-off tube. It took a brown (regulated positive) wire and two others. Does anyone know what the other little device is under the battery? I chucked it in the bin and the bike still seems to perform all operations as expected.

Is it the unit that tests the warning lights on the instrument cluster?

Here is an image from another thread:

Hmm...I accidentally put this under Engine which it clearly isn't. Can a moderator move it to electrical for me, please?

Mid life crisis wrote: Is it the unit that tests the warning lights on the instrument cluster?

Good question. The instrument cluster was one of the gutted items. I am going down to what is necessary to start/run and basic lights. The only gage remaining is the speedo.

My next question was going to be "do all your warning lights come on when you first turn the key?". Obviously you can't answer this now!

I have added an image in my first post. Good luck with the clean up!

Now that there is a picture...yeah, I think that's the thing. It sure looks right. I think it was a brown, a blue, and a yellow going in. It was roughly that shape and was bolted onto the bottom of the battery box.

Part of the goal of the clean up is to open that battery box area entirely and move the battery itself under a custom-shaped seat. I have most of the parts cleaned out at this point so it is mostly tidying up wires, extending the battery cables, and shaping a seat/fabbing a battery box.

kjelderg wrote: ....
Under the battery box, I had two components. One was the regulator/rectifier. The other is a smaller squared-off tube. It took a brown (regulated positive) wire and two others. Does anyone know what the other little device is under the battery? I chucked it in the bin and the bike still seems to perform all operations as expected.

That is the fuel check switch. In the wiring diagram it's listed as the Warning Light Self Checker (in the w. diagram drawing it's near the 20A fuse). It may also serve as an outage indicator switch for the brake light. The thing is a handy device.