Conditions for Setting the DTC
WARNING: This page is about a different car, the 2007 GMC Sierra and 2007 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
DTC P0703 sets when the vehicle accelerates 10 times with the brake switch in the ON position, or decelerates 10 times with the brake switch in the OFF position.