Odd noise while driving - sounds like somebody called the cops
 

I hope someone can shed some light on this for me. I have been through the owner's manual 3 times, had my wife check in case I overlooked something, searched this site at length and googled - nothing yet.

The situation is this: in my 2004 CLK320 there is a randomly intermittent noise while driving, sounds like the cops have the siren on and I should pull over. I started looking around to pull over the first few times it happened this weekend. It is two discrete sounds, 1 second long each with a 1 second silence between, and starts low and ends high (like a police siren).

Cheers, Tom

How about a video?

Give us more info on where it sounds like it's coming from. A rear wheel? Front wheel? Engine compartment? If engine compartment, front or rear of engine? Only does it while moving? Etc.

Does it do it when it is hot out and your a/c is on, and you are not moving too fast? The cooling fan on these cars can sound like a siren at times.

Thanks for the replies. Unfortunately I have an embarrassing confession to make. It happened again today, and it turns out that it was my Tom Tom GPS.

It happened while I was holding it and making changes. The odd thing is it has never happened in the past several years, so my first inclination was something a bit off in my Mercedes. Yeah, shame on me, but I never would have guessed it, and the noise appeared to come from the dash. Now I need to find out why the GPS is making this noise, so off again to find the cause.

My apologies.

:smash:

Maybe it knows the speed limits and you are exceeding them? The NAV system on my wife's new Jeep GC actually shows the speed limits. It doesn't tie into the vehicle speed for any sort of alert, but it is nice to be able to check, especially when on an unfamiliar road and no signs in sight.

Hah - I'm pretty sure that newer TomToms with speed and traffic camera locations make this noise when you are approaching them. I believe it can be toggled via the settings menu. Something like services -> Speed Cameras -> Alert Settings if I recall correctly.

Yes, it's embarrassing to no end. The odd thing is it has never happened before, and it does show the speed limit with a red indication of when you exceed it. I started using an older model that gives an azimuth, so when I'm lost I can know just how lost I am. I'll check the settings and see what I can find out.

Thanks to all for the input.