I think Voight is supposed to nail that black guy he's always getting money and info from, who is a big dealer. He uses the money to finance his little fix up projects--kids he's saving. Either that or there is some other big time crook he's supposed to be nailing for them, and so far hasn't.
He did a lot of awful things last season when he was only on Chicago Fire as a villian--all in the name of "protecting" his son....but he really hurt firefighters and their nearest and dearest, or scared the daylights of them. Presumably they can hold some of that over him still. He was really awful last year, so it is hard for me to warm up to this new kinder gentler Voight. Too bad as without that memory I wouldn't much care what he did in the past.
I do love that they keep mentioning the Molly's bar (from Chicago Fire), but after all Antonio's sister is a co owner, so of course they'd give it business.