Central locking Mercedes 190e

I have a1989 190e mercedes 2litre that i found had the vacume pump for the centre locking missing,i replaced this and still the centre locking does not work.When i activate the door locks the vac pump buzzes for about
30seconds but the centre locking does not operate.Has anyone got any suggestions including how to test to find a solution to getting the centre locking to work again?many thanks
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There is leak somewhere in the system. You need a hand vacuum pump to check.
Go to google to find the posting from me on 5/24/05. Subject was "Re: '86 190E - Need Central locking system Diagram or Flow Chart"
cococola wrote:

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Thank you,can anybody explain how i check the pressures on my central locking and how i elliminate the problem that is causing my locks not to work on centre locking.I did get the flow chart (thank you wan-ning tan)I just need talking through the diagnosise and is there any other things that i can check? many thanks.
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Somethings I can think about: 1. Make sure the pump does output BOTH vacuum and pressure. Turn the key on front door lock to test that. 2. Follow the vacuum diagram. Check all tubing. Is there any one disconnected or broken? Don't remove the tube to inspect. You can easily pull out the tube but putting back requires a lot of removing (seat, carpet, etc). 3. ALL tubes and vacuum elements in the system should hold vacuum (use your hand vacuum pump) for at least a minute, meaning the vacuum reading should not drop fast. The best place to test is at the Tee or fork. Just make sure which tube goes to where. 4. All elements should lock when vacuum is applied. If not, element is bad. A branch can be isolated to test. Disconnect at the Tee/fork then use caps to block. 5. Remember to retest everytime something is replaced. There may be multiple failures.
Good luck
cococola wrote:

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