Back brakes

[stuart scott]

Can i purchase something simple to plug in to my s4 to wind in the pistons so i can change the pads?

 

[NHN]

There are diag tools out there or you could jack up, steady the front wheels so no movement, remove rear wheels, turn ignition on, turn of epb, remove power to rear calipers or battery of, so they can't wind in, that's of course the cheap way & not without possible caveats.

It's upto you & your budget.