It you have the wire harnesses, can S5 turn signals, headlgihts, cruise, and wiper switches work without modification on an S4? My headlight and cruise swtiches are burnt out and i found a good deal on a S5 set.

 

To my knowledge the headlight and wiper switches are interchangable between s4 and s5. I am almost 100% sure that the cruise control switch isn't. You need to have the entire cruise system to be of the same series. No idea on the turn signals.