The only parts recommended by Ford Motor Company for Ford, Lincoln, and Mercury vehicles. Motorcraft Potentiometer is a three-terminal resistor with a sliding contact that forms an adjustable voltage divider. If only two terminals are used, one end and the wiper, it acts as a variable resistor or rheostat. In Ford cars and trucks, a Potentiometer is connected to the vehicle s accelerator pedal and sends an electrical signal to the Engine Control Module (ECM) to control engine speed response. Motorcraft Potentiometers are manufactured to exacting Ford OE specifications and quality standards.