The sensor on the crankshaft measures the rotation speed of the crankshaft and with this data, the computer can determine engine timing sequences and apply this data with the camshaft position sensor to determine the correct injection of fuel and ignition timing. To check the sensor first unplug the wire harness plug, next hook up an ohmmeter to the sensor terminals A and B, the resistance should be checked between 520-580 ohms at 68°F (20°C); the sensor must be replaced in case the resistance is out of this range. Also, check air gap between crankshaft pulley and sensor, it must lie between 0.040-0.080 inches (1-2 mm), otherwise, check crankshaft pulley or change sensor. To remove and install, first disconnect the negative battery cable, and any accessory drive belts you may require removed in order to reach the sensor, and the engine oil dipstick tube may need to be removed. The next step is to remove the sensor attaching bolt and remove the sensor out of the engine, which must be installed in the opposite order of the removal.