what about diy check engine codes?

im throwing a vehicle speed sensor and i just bought one from a junk yard and still no speed?
i took out the dash and unplugged the gauge cluster and checked the wires but still nothing.. i was working for awhile but its back and now it wont move...
help?
i took out the dash and unplugged the gauge cluster and checked the wires but still nothing.. i was working for awhile but its back and now it wont move...
help?
