What is this for? - from control box

[Can_38]

New to me boat with a 40hp force has an empty connection coming from the control box, what is it for?

http://i855.photobucket.com/albums/ab115/Can-38/48707e768739862bef9a157753e45af6_zpsc93b5a06.jpg

http://i855.photobucket.com/albums/ab115/Can-38/2ae16178a396c6ad80138170c16e09ce_zpsd8f629c9.jpg

Thanks

 

[Can_38]

Re: What is this for? - from control box

The control box is a mercury that is why I originally posted in the Mercury section.

 

[wired247]

Re: What is this for? - from control box

Thats the plug in connector for your tach