First thanks to M.B. Doc for the info.
It's rather simple, lift up the main arm rest, open the
slide cover and remove all junk!!!
Carefully lift out bottom liner and you will see the cable
slide. It is a pressure lock connection on the cables.
What I did was to open the rear vent all the way, then take
some pliers and push the rear cable towards the front while
holding the connector (just a 1/4" or so.
Now close the rear vent and you will feel some resistance
before it "clicks" closed. Gently, but firmly, keep closing vent
until you hear the click. You will see the rear cable slide slightly
in the connector. You are done!
Make sure that the cable slide (connector) moves freely and
the cable does not slip. If it does, you may have to compress
the cable conneector around the cable. Remember, with all MBZ
parts, DO NOT FORCE! Mocho means $$$!
BTW, some S500's have climate control in the back, so there may be
more stuff under the box, and I do not know how that system is
controlled.
BOBB