Why would speedometer stop working after changing throttle position sensor

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I had a bad TPS. Before changing I disconnected the negative battery cable to clear check engine light and left it off until the TPS was changed then reconnected and started vehicle. When I started the vehicle I noticed both the RPM and speedometer needles all the way over on the left side of the gauges. The RPM needle dropped back where it was supposed to be but the speedometer stayed at max speed.