The camshaft position sensor (CMP) is mounted inside of the distributor housing, and is part of the distributor assembly. It consists of a rotor plate, a photo diode, and light emitting diodes (LEDs). The rotor plate has 360 slits which generate a 1° signal, and 6 slits which generate a 120° signal. As the distributor rotates, signals are generated as the rotor plate passes between the photo diode and the LEDs. The signals are sent to the PCM to indicate engine speed and piston position. The PCM uses the information to control the fuel injection, ignition timing, and other functions.
Removal & Installation
The camshaft position sensor is part of the distributor assembly, and must be replaced as a unit. Please refer to Engine Electrical, Distributor Ignition System, Distributor, Removal and Installation for the procedure.
- Remove the distributor from the engine. Leave the distributor wiring harness connected.
- Using a voltmeter set to the DC range, connect the negative lead of a voltmeter lead to the negative battery terminal.
- Insert the positive lead probe into the back of the distributor connector in pin 2.
- With the ignition switch on and the engine OFF , rotate the distributor by hand and observe the voltmeter reading. The reading should fluctuate between 0 and 5 volts.
- Disconnect the positive voltmeter lead from pin 2 and connect it to pin 3 of the connector.
- Rotate the distributor by hand and observe the voltmeter reading. The reading should fluctuate between 0 and 5 volts.
If the voltage is not within specifications, the sensor may be faulty..