Hello,

Occasionally, in the winter weather, the vacuum pump under the right side of the back seat runs for about 10 to 15 seconds after I unlock or lock the doors via key or internal door lock pin.

If this happens, the doors are very hard (hard to push pin or hard to turn key) to unlock or lock and only the door you are working with will do the lock or unlock action.

After the sound goes away, (the pump stop pumping), everything is normal again.

I am looking to install a keyless entry system on my car and want to make sure this problem is taken care of first.

Any suggestions on where to look?

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2006 BMW M5 "Heidi" @ 109,000 miles
2005 MBZ C55 AMG "Lorelai" @ 165,000 miles
1991 MBZ 300E "Benzachino II" @ 165,000 miles
1990 MBZ 500SL "Shoshanna" @ 118,000 miles

(On the hunt for a good used M103 engine as of 6/10/23, PM me if you have one to sell!)

either the pump runs but does not pump or you have a large leak in the system.there are two limit switches on that pump one for vacuum when locking and one for pressure when unlocking.

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David S Poole
European Performance
Dallas, TX
4696880422

"Fortune favors the prepared mind"
1987 Mercedes Benz 420SEL
1988 Mercedes Benz 300TE (With new evaporator)
2000 Mercedes Benz C280
http://www.w108.org/gallery/albums/A...1159.thumb.jpg