I hear a buzz noise when I accelerate beyond 20km/h and that buzz noise lasts for some 2-3 seconds. The thing is that that buzz noise had a faster tempo before but now it seems as it is struggling. So, when I start the car and I pass 20km/h the buzz noise starts, it lasts for some 2-3 seconds and it's gone and it's not heard until I turn off the car. It was the same when the car is turned off. When I push the car and when it goes faster than 20km/h I hear that buzz noise. My question is what operation does the car perform when I pass the speed of 20km/h?
I'm pretty sure that it's got nothing to do with climate motor flaps, because the car produces this buzz noise also when it's off and when I push it to that speed with the ignition on. I suspect that it has something to do with something that's in the cockpit in front of the driver.
The car is E34 535i.
The Buzz comes with the electrics on. It's a normal thing, that buzz was present always. I just don't know what operation does the car perform with that buzz. It's a similar sound to a sound when you open a CD/DVD ROM or when you eject a CD or DVD from an audio device and that sound comes from the cockpit, from the speedometer to be precise. So, in that moment the electronics performs some kind of an operation. I'm only trying to find out which operation is it performing?