I think I have to replace the block heater on my 580k, I checked the cord and it seems OK but when you plug it in........nothing. It's located in the forward frost plug hole above the starter.
if it is an oem heater there is an allen head screw in the heater face, just loosen it up completely as there is a toggle on the other end that draws it tight. they can be a bit difficult to break loose but are sealed with an oring. mEl
It can be tough to remove .I had to use a body dent puller to get mine out of my 580 SE .Check the plug out first. This the only way to go as far as a block heater goes .It is direct beside the cylinders and in 15 minutes pluged in it should fire right up