The crankshaft position sensor on the 2003 Ford F-350 diesel is located behind the crankshaft pulley. It senses the rotation of the crankshaft and sends the information via a voltage signal to the computer. The computer uses the information to provide the proper air-to-fuel mixture for optimum running and fuel mileage. The crankshaft sensor is a black, plastic sensor with a wiring harness connector and a metal bracket.
Park the vehicle and turn off its ignition. Open and secure the truck's hood. Locate the accessory drive belt tensioner pulley in the engine compartment. Fit the appropriate socket onto the accessory drive belt tensioner pulley. Rotate the pulley toward the engine, then lift the belt off the crankshaft pulley. Leave the belt on the other pulleys.
Locate the crankshaft pulley. Remove the crankshaft pulley bolts, using the appropriate socket. Remove the crankshaft pulley.
Unplug the crankshaft sensor, using your fingers. Remove the retaining bolt on the metal bracket, using the appropriate socket, and pull the sensor out of the engine.
Insert the new sensor into the engine and firmly tighten the retaining bolt. Plug in the wiring harness connector, ensuring that the plug snaps into place. Reinstall the crankshaft pulley and firmly tighten the bolts. Rotate the accessory drive belt tensioner toward the engine and slide the belt onto the crankshaft pulley. Allow the tensioner to fall gently back into place.
