the hum

[london_keeps]

When unlocking my 1995 E200 estate (W124), there is a hum from somewhere behind the right rear seats, which goes on for about 10 seconds. Similarly, when I lock up, there is another hum for similar length. What is it doing?
I am sure it is doing somethig clever and I have a few ideas but I thought I'd ask you guys for an answer.

Thank you very much.

london_keeps

 

[dstrong]

it is the vacuum pump for the central locking, seat lumbar support and lots more

 

[london_keeps]

thank you

ok. thank you.