I left my car running and locked all 4 doors C280 2000. The trunk was open and still open. I hear the locking vacumm pump is in the trunk but do not know if possible open car. I unplug the battery cables and stop running the car NOW I do not have keys..? Any IDEAS

Should be in the trunk on the right side behind a cover (From what I gathered in a quick google search).

You'll want to disconnect the vacuum hose from the pump and then you'll have to blow in to get pressure or suck to pull vacuum to unlock the doors. If memory serves me you have to pressurize the system to unlock. You could use an air compressor with low PSI setting on the regulator to provide pressure if blowing in to the locks doesn't work.

This should unlock your doors providing the vacuum system is in good working order.

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'98 E300 Turbo "Juliette"
'85 Federal 300TD

To stop the car unplug the fuel pump fuse or relay. Some cars have this behind the right trunk trim cover. Fuel pump should be under the car just ahead of the right rear wheel.

As other have said, use the vac / pressure hoses to unlock the doors.

Thanks for the tip. The car is not running now, it stoped.
What I would like to know is how to unlock the doors from the trunk vacuum pump Please explain DO NOT HAVE air compressor The CAR is in the basement of a building

This is what you need to do if you can locate the vacuum in the trunk. I have not done it before but it should work based on the principle of the door system.

1) Locate the pump.
2) There is ONE vacuum hose attached to the pump
3) Remove the hose and blow into the hose as hard as you could.
4) All doors should unlock.

Alternately, if the pump is NOT in the trunk then you may be able to find the vacuum hose to the trunk or gas cover lock. Undo the hose and blow towards the other side, not to the trunk or gas cover lock.

Good luck.

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

NO COMPRESSOR, use your mouth or a bike pump, low pressure.

does the car have a sunroof? Maybe you can find the sunroof motor mechanism in the rear and turn the emergency knob. I know on the W126 it is on the Left side of the trunk near the antenna mast

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2001 E55

2001 E320 Sedan

2001 Subaru Legacy

2006 SLK280

2016 Subaru Outback 3.6

Its already been a whole day, if you haven't gotten your keys by now call a lock smith and be done with it.

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1990 190E 3.0L

Sorry but I never mentioned where I was located. I am in Caracas Venezuela and here the MB dealer does not have keys or USD to buy keys and told me it would be 30 days approx. to get a key from Germany. The lock smith here do not mess with luxury cars, they can ruin the job.
Since I used to live in USA, I normally call on US for advice, but not in this country where you may risk a lot...
One Benz private Shop sent a mechanic this morning and since the trunk was open, he located the locking vacuum pump and placed a hand low pressure air pump in one of the hose holes and pressed the air pump and the back door lock just opened and DONE... I also import from US parts ans accessories..

Thanks again for your suggestions...