Iveco 65C15 brake lights come on at random with engine off?

Iveco 65C15 L E B my brake lights come on at random went engine is on or off,switch on peddle was faulty and has been replaced, relay was also replaced. I am told abs control module has something to do with brake light operation but where is it located? can someone halp because at the moment it ether flattens the battery over night or misleads anyone whos behind me on the road.