# Whirring noise after shut-down



## 3LOU5 (Jun 14, 2002)

The past few days, I have noticed a little whirring sound emanating from the front after I shut off the motor. The noise lasts between 3 to 5 (no pun intended) seconds after I turn the key to the off position (yes, I timed it). I've never noticed that before, and was wondering if anybody here has experienced it as well.

:dunno:

And if anyone has or knows about this sound, could you please direct me to a thread or link? 

Thanks in advance.


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## The HACK (Dec 19, 2001)

3LOU5 said:


> *The past few days, I have noticed a little whirring sound emanating from the front after I shut off the motor. The noise lasts between 3 to 5 (no pun intended) seconds after I turn the key to the off position (yes, I timed it). I've never noticed that before, and was wondering if anybody here has experienced it as well.
> 
> :dunno:
> 
> ...


It's the ABS pre-charge pump discharging. See if you can notice the same noise when you first turn your key over to position II as well...That's the ABS pre-charge pump CHARGING.

The pump stores some brake fluid from the reservoir so that it can actuate the brakes without affecting the pedal or the master brake cylinder's imput.

Next time, keep the engine running, leave the hood up, have a buddy stand by the brake reservoir and see if it fills back up when you shut off the engine, and see if the "sound" eminates from underneath the reservoir.


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## 3LOU5 (Jun 14, 2002)

Thanks for the prompt reply, Hack !

I'll try and see if indeed that is the case. If it IS the ABS pre-charge pump, do you think it is going bad? I just don't remember the sound being so noticeable since I bought the car last summer.

I suppose a trip to the dealer is in order if the sound gets longer and louder.

:eeps:


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## visor (Sep 7, 2002)

It has to do with the air vent flaps moving/resetting positions.

See your manual page 187 under "Self diagnostics"

_Even after you shut off the engine, the overall functional status of your vehicle is monitored. For example, all of the flaps of the heating and ventilation system travel to the nearest limit posi-tion. This ensures that the defrost func-tion 
is always available even if a malfunction in the air conditioner 
system/automatic climate control should occur while the vehicle is 
parked overnight, for instance.

A calibration cycle runs every tenth time the engine is shut off. During this cycle, the actuator motors of all the heating and ventilation flaps travel to their limit stops in both directions. The limit posi-tions and the return travel paths are checked in this manner in order to ensure that appropriate adjustments for the operating elements can be made at any time._


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## 3LOU5 (Jun 14, 2002)

visor said:


> *It has to do with the air vent flaps moving/resetting positions.
> 
> See your manual page 187 under "Self diagnostics"
> 
> ...


Thanks for the reply, but I do not believe it is the actuator motors of the flaps because it is happening EVERY time I shut down.


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## visor (Sep 7, 2002)

Turn off the climate control, and then try turning the key to off position and see if you still hear the noise.


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## BWTX540i (Mar 19, 2002)

I hear the same sound, but it is when I am driving and come to a stop. A few seconds after I come to a complete stop, I hear the sound. It sounds as if it is coming from the driver side of the car, somewhere just under the dash.


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