I tapped the wire first with no effect. Then I cut the wire, which made things worse (dead speedo).I have since reconnected the wire & the speedo is working again, although the calibration may be off. As a last ditch effort, I'm gonna try the diagnostic routine in my Ford service manual CD.

98 Contour LX V6 MTX svt exhaust, E1 rims, Cougar shift knob,PIAA fogs, Silverstars, KKM pedals 85 F150