Accelerator Pedal Position (APP) Sensor
WARNING: This page is about a different car, the 2008 Ford Pickup, 2008 Ford F550 Super Duty, 2008 Ford F450 Super Duty, and 2008 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
The Accelerator Pedal Position (APP) sensor is mounted on the accelerator pedal on diesel applications. The APP detects the position of the accelerator pedal and inputs this information as a voltage signal to the PCM. The PCM uses APP sensor information in determining line pressure, shift scheduling and Torque Converter Clutch (TCC) operation. Failure of this sensor will cause the transmission to operate at high line pressure to avoid damage to the transmission. This high line pressure causes harsh upshifts and harsh engagements.