Hello Amigos,
My brother in law needs your help. He just took his CLK320 out of winter storage only to learn that he has very low pedal pressure and rear brakes aren't working (no friction whatsoever). Not sure if this has anything to do with the issue, but the ESP light is on and he lost his battery charge over the winter. Battery is fully charged now.

Any advice?

 

This could be several things. One could be bad calipers. The other issue could be faults in the ABS/ESP control module. I'd pull codes first to see if there's an ESP fault.