He squints up at Ianto as he talks, trying to discern what this answer actually means. He... does want to use the bathroom first, maybe? But only if John deactivates anything in it?

"Alright," he says, finishes hauling off his boots -- sets them aside as he pads in. For a moment the entire place goes dark, and John curses softly under his breath. "No, no, lights are fine keep the --" The lights snap back on, and John is illuminated squinting around the small bathroom. "Yeah," he says vaguely, and begins things to make sure he's not turned off anything keeping them or the water from freezing. "I think that's it...? Maybe? I dunno, there's not exactly a big control panel that tells me what I've turned off here."

This is where displays come in handy when you're a technopath and just guessing at what you're doing.