WTF! Please, Help.
 

So my dad was driving the pickup the other day, all was good and dandy. After he got done moving a bull he came home and proceeded to shut the pickup down. Still, all good. Well, he turned her off and heard a wierd noise comin from the engine bay, almost like the starter was still going. Well he got out, popped the hood up and looked around, wasn't the starter but the noise was originating from the brake cylinder area. Looked closer and discovered it was this-

He disconnected the plug from the bottom of the box, don't know the name of it, and it stopped making the grinding noise. But once it makes contact it makes the noise again. And it won't stop, even with the engine off and the batteries disconnected.
One side-effect of this is the ABS and BRAKE lights are on in the dash, so I'm guessing these are somehow connected. No codes are showing, via the key method, I'm lost guys, please help.

It's the ABS module, some people eliminate them and then you just won't have ABS. Or you can replace it, but I have heard they can be pricey. :c:

Thank you tiremann :c:
Any ideas as to why it went out? Or was it just it's time? Hell, it's got 594,xxx miles, maybe it was lol