Electrical (servo?) noise from rear of car

[JUV]

This is a really weird one, and since it's been happening since we got the car in September with no apparent ill effects its probably not worth worrying about for a second, but I just wondered if anyone could satisfy my curiosity on this one.

The car is a 2002, 1.2S Polo, with most of the extras (e/w, aircon, door lights, handy drawers under the seats etc) if that makes any difference. When it's parked up and the engine is switched off, and ignition off, there's a very soft but noticeable noise which repeats from the back of the car - it puts me in mind of some kind of servo - just repeatedly humming for a second or so, then off, then humming again, and off and so on for at least a minute or two. Last time I checked, I think with the keys still in it just seemed to carry on continually, but when I took out the keys (I was still in the car with the doors shut) it stopped after a few moments.

It's barely noticeable and I can easily believe that whatever it is is working exactly as designed - but I just can't work out for the life of me what it actually is, and what its doing! Anyone got a clue?

[K.I.T.T.]

My car give's me a soft hum now and again, but I think it's when I turn the ignition on rather than off...I believe it's just the fuel pump priming itself.

Ash

EDIT: mine doesn't go for a minute or two (didn't read that bit). Couple of seconds tops. Mine's a 1.4 TDi, so it's quite different from yours, but thought I'd give you my experience anyway.

[chewy]

Its the fuel pump. If you turn the ignition on but don't start eh car after a few seconds you will hear a click. Thats the pump resetting itself

[JUV]

Ah, okay, that explains I guess. Does seem a little overactive, but I guess it knows what it's doing! Thanks all.

[RITCHAT]

Only thing at the back that is likely to hum is the fuel pump, some are a bit noiser than others. only time I get any noise is on switching the key to start , this is when the system is priming itself before the engine starts a kind of swirling type of noise on the diesel anyway. nothing to worry about

[K.I.T.T.]

Only thing at the back that is likely to hum is the fuel pump, some are a bit noiser than others. only time I get any noise is on switching the key to start , this is when the system is priming itself before the engine starts a kind of swirling type of noise on the diesel anyway. nothing to worry about

Yeah, I get that too when I turn the ignition on. Kind of a swoosh draining noise...hard to explain

Ash