Possible Causes

WARNING: This page is about a different car, the 2006 Mercury Grand Marquis and 2006 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

A belt tension sensor circuit fault can be caused by:

wiring, terminals or connectors.
an open circuit.
a circuit short to voltage.
a circuit short to ground.
a faulted belt tension sensor.
a faulted OCS ECU.