To replace the windshield wiper arm on a 2005 Pontiac Grand Prix you will need a flat head screw driver. The first step is to position the wiper blades in the up position. Next open the hood and locate the pins that hold the wipers in place, use the screw driver and take the screws out then take off the wiper blades. Next put the new wiper blades on making sure they are the right ones for the vehicle. Screw them back into place. Finally close the hood and turn the wipers on to make sure they work accurately.