The speedometer in my 2004 2.2L EcoTec stopped working yesterday.

I had just finished changing the thermostat (stupidest.placement.ever), hooked the exhaust manifold back up, and took it for a drive. It was then that I noticed the speedometer wasn't working.

Could this have been caused by me knocking something loose when I was fiddling around with the thermostat/manifold? If so, where is the cable so I can check to make sure it is hooked up correctly? Thanks.