Speedometer Malfunction: Description
WARNING: This page is about a different car, the 2008 Toyota Yaris. However, it is still accessible from the selected car via links, so may be relevant.
w/o ABS:
The combination meter assembly controls the speedometer in accordance with vehicle speed signals from the speedometer sensor.
w/ ABS:
The combination meter assembly controls the speedometer in accordance with vehicle speed signals from the brake actuator through the CAN communication system.