i know this is an old post and i should of fixed it by now but i haven't had a problem with this problem until recently

so my I cleaned all the fuses and such in the fall and it was fine again

then just randomly ooking through the Mercedes Benz E-Class Owners Bible I came upon what might be troubling my car

seems that relay in position H is what's causing all the problems

it controls the Turn Signal, Heated Rear Window, Hazard Lights, and the Wiper Motor....wow all the things that don't work from time to time

good thing is that FastLane has it for like $80 part # P2020-32725

so recap of what to change (if looking at ur engine bay)

if u go to ur Main Relay Panel (behind the Main Fuse Panel) the relay in question is the middle front one (closest to the front) also its one of the biggest one in the middle row