What does that black box do in the rear bumper

[johno]

Well today while taking the t case and transmission off. I noticed there was a cut line it was rubber into hardline that then ran to the back with the brake lines. What does this line do looks like it hooks up to a black box in the back wondering what this does

[Unforgiven]

Is it next to the frame rail by the driver side rear tire? If so it's probably your evap canister, used for emissions.

[tscompusa]

its in the rear of the evos? interested. its in the engine compartment on a dsm 4g63. or do cars have one in the front and rear?