what is the thing inside the gauge cluster above the speedo?

[giantkiller]

The thing that looks like a fuse in green glass. Right above the speedo clipped into the housing. Has white wire with black stripe and black wire. I think it's no.9 on the wire diagram." reed switch"?
What is it? What does it do? Is it necessary?

[Arnie]

It is a reed switch. 
It is normaly open and closes when a magnet comes near. 

It is part of the auto-cancel indicator device. 
This allows the black-box controller to count how far you've traveled. 
That count AND time decides when the signals are cancelled.
Make sure it is properly seated. 
If it gets knocked out of position, your signals will not cancel.

[giantkiller]

Thanks Arnie. My uneducated guess was that's what it did. I'm cleaning up the unnecessary stuff in the gauges,since I'm using digital gauges. And just wanted to make sure