Instrument Cluster Gauges: Tachometer
WARNING: This page is about a different car, the 2005 Mercury Montego, 2005 Ford Freestyle, and 2005 Ford Five Hundred. However, it is still accessible from the selected car via links, so may be relevant.
The instrument cluster receives the tachometer data from the PCM over the communication network and commands the tachometer pointer between 0 and 7,000 rpm, according to the data.