98 civic ex, completely stock with high miles(the wifeys car). just waivered the check engine light for a oxygen sensor code. My speedometer is not working, but my tach is working with no problems. The speedometer works only half the time but usually more when i get it over 40 mph, then will reset itself occasionally(like when your alternator is going out and your gauges reset). My question is where are the grounds located so I can trace the problem. My next step is to take out the cluster and check the connections. Tell me what you guys think.

 

Check the VSS?

 

Before he asks... it's RIGHT on top of the transmission.