WARNING: This page is about a different car, the 2013 Acura MDX, 2012 Acura MDX, 2011 Acura MDX, and 2010 Acura MDX. However, it is still accessible from the selected car via links, so may be relevant.
As the accelerator pedal position changes, the sensor varies the signal voltage to the PCM which then controls the throttle position.
Fig 1: Identifying Accelerator Pedal Position (APP) Sensor And Accelerator Pedal Module