I have a 02 f-250 5.4L XLT lariat . I have a part in the engine compartment i can't find any part #, or in any diagrams. I am curious what it does. It is a long black tube looking device that appears to have a vacume hose attached to rear going under engine. It is in the front driver's side above the wheel well. It makes a sound you can hear in cab of truck when overdrive kicks in. Any help would be appreciated.

 

Pics would really help...........

 

Here is what I could find.



it is the part in red box<br/>