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Q: Power lock stop working, on 1994 Mercedes-Benz S320

power locks don't work. all doors don't unlock even the main switch, including doors/trunk closing assist. I check switches & fuses are good.
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I have a 99 its 320 and I had the exact same problem as you. While troubleshooting I found that my vacuum pump which is located under the rear seat on the passenger side, has quit working. I tested the pump and it is no good and must be replaced. I since then have replace the pump and everything is back to normal working condition. I hope this helps you and good luck
I had exactly the same problem relative to my 1999 S320. In my case, the vacuum closing of the trunk and rear doors was not working. Solution was to replace the defective vacuum pump located in the truck floor. Now all is working as it should. You should know that there are two vacuum pumps - one under the rear seats and one under the trunk floor.
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