When I bought the truck, I always wondered what this what, but I never could figure it out.

There is also a on / off switch next to it. Maybe it's something to do with towing? I'm not sure, but what I press on my breaks. It'll light up. The more I press on the brakes, the more lights show up.

 

that is an electric brake controller for trialers

 

Ah, okay. Thanks.

I never use trailers, so I don't think that thing really does me any good then but get in my way under there. ><

 

Yup. X2

 

At least you know its there if you ever have to tow a trailer!

 

My truck has one too. I disconnected it.