The function of the Camshaft Position (CMP) sensor is to let the ECM know whether the camshaft is on the first or second revolution of an engine cycle, allowing the engine to know which of the pistons are approaching TDC and, in combination with the crankshaft position sensor, to know which cylinder needs to be ignited. The CMP sensor consists of a trigger rotor which rotates at the same speed as the camshaft and a Hall effect switch, the ECM supplies 5 volts to the Hall effect sensor which grounds when the rotor passes the switch, this will send out a zero voltage signal and the sensor is shielded and will send the 5 volt signal to the ECM. To test the CMP sensor, first unplug the sensor and remove the negative battery cable. Measure the voltage at terminal 3 with a voltmeter when the ignition is ON, it should be the same as the battery voltage. Next, check on the signal return at terminal 2, which should be around 5 volts. For the ground circuit, measure the resistance from terminal 1, which should be 0 ohms. If continuity is out or not there, repair the circuit and if continuity is fine, replace the CMP sensor. For removal, detach the negative battery cable, remove the air inlet hose, unplug the sensor connector and remove the retaining screws to remove the sensor. To install, place back the sensor, tighten the bolts, reconnect the sensor, reinstall the air inlet hose and reconnect the negative battery cable.