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Old 03-12-2001, 02:11 PM
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MBenzNL MBenzNL is offline
Join Date: Jan 2001
Location: the Netherlands
Posts: 1,417
I recall posting an answer to this problem some minutes ago...

The rear headrests are partial electrical and partial vacuum controlled. The switch on the dash is connected with an electrical valve that allows the engines vacuum system to tear down the rear headrests. When you push the button, the valve is opened and the vacuum pods under the rear deck will take care of throwing down the head rests.
* Do the headrests fall down when you push the button a little longer? (this will indicate a vacuum leak in the system).
* Is there a blown fuse?
* Do you hear a (minor) clicking sound at the rear deck when you push the button? (you can hardly hear it when it does function properly).
Since both head rests don't fall down, I presume you have a problem with the electrical valve or vacuum hose from engine to electrical valve.

...just some thoughts...

The picture above shows the electrical valve on the rear deck of a C class (in front of the speaker). It is connected to one incoming vacuum hose and two outgoing vacuum hoses. Forget about the speakers in the picture...

1990 300SL-24
1993 C250D
with a minor 600+k kilometer
(the Netherlands)
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