That's a common size for handsfree sets for phones, so maybe a remote microphone?

 

The plug is not factory. Not for NAV either as the factory NAV plug is square and white...

 

What's weird is that it's a plug. I would've put in a jack. Any voltage placed on a plug is subject to shorting out and hurting something.

 

good point.

I vote, kill the cat and get curious.

 

It's probably audio, which doesn't have much voltage, and if it's simply a speaker or microphone, it wouldn't have any voltage until it's plugged into the device.

 

So youre going to have to take it all apart and find out where it goes to it looks like

 

Follow the rabbit down the hole Alice!

 

lots of phones use 2.5mm. my Moto Q does, as do many blackberries, and many many other models of phone.

I got a 2GB memory card with music in my Q, so I plug into my pioneer deck with a 3.5mm cable attached to a 2.5mm adapter. Maybe I should do what that guy did.

 

look on the registration, call the guy, and ask him... he might be able to tell you

 

maybe for a heated coffee mug?