at the VSS there should be three wires.
blk should be ground
Blk/yel should have 12volts on it with the key in run.
blu/wht is the signal that runs to the cluster and the ECU.

the signal runs from there to the 20pin brown connector under the blower fan under the dash. there are three wires in that connector that are connected together for other things. my guess would be that your problem is between there and the VSS itself.

**edit, check the ground at the thermostat housing. the O2 gets it's ground from there. might fix two problems at once.