MonteCarlo 2000

Camshaft Position Sensor

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Operation



Specific to:

Buick Century 1997-2000

Buick Regal 1997-2000

Chevrolet Lumina 1997-2000

Chevrolet Monte Carlo 1997-2000

Oldsmobile Cutlass Supreme 1997

Oldsmobile Intrigue 1998-2000

Pontiac Grand Prix 1997-2000

The PCM uses the Camshaft Position (CMP) sensor signal to determine the position of the No. 1 cylinder piston during its power stroke. The signal is used by the PCM to calculate fuel injection mode of operation. If the cam signal is lost while the engine is running, the fuel injection system will shift to a calculated fuel injected mode based on the last fuel injection pulse, and the engine will continue to run.

On the 3.1L and 3.4L (VIN E) engine, the Camshaft Position (CMP) sensor is located on the timing chain cover behind the water pump near the camshaft sprocket. As the camshaft sprocket turns, a magnet in it activates the Hall-Effect switch in the CMP sensor. When the Hall-Effect switch is activated, it grounds the signal line to the PCM, pulling the CMP sensor circuit's applied voltage low. This is interpreted as a CAM signal. The cam signal is created as piston #1 is on the intake stroke. If the correct CAM signal is not received by the PCM, a DTC will be set.

On the 3.4L (VIN X) engine, the Camshaft Position (CMP) sensor is mounted to the left bank camshaft carrier, towards #6 cylinder. A 3-wire harness connector plugs into the sensor, connecting it to the Powertrain Control Module (PCM). The PCM applies a signal voltage to the sensor. The left bank exhaust camshaft has a tooth machined into the casting. The camshaft position sensor is separated from the exhaust camshaft by an air gap. As the exhaust camshaft rotates, the machined tooth aligns with the sensor. The signal voltage to the sensor is pulled low. The PCM interprets the change in signal voltage as an indication of camshaft position. The CAM signal is created as piston #1 is on the intake stroke. If the correct CAM signal is not received by the PCM, a DTC will set.

On the 3.5L (VIN H) engine, the Camshaft Position (CMP) sensor is located at the rear of the forward camshaft carrier, near the engine lift ring bracket. The sensor signal, when combined with the Crankshaft Position sensor signal, enables the PCM to determine exactly which cylinder is on a firing stroke. The PCM can then properly synchronize the ignition system, fuel injectors and knock control. The camshaft position sensor has a power, ground and signal circuit. The PCM supplies 12 volts to the sensor. The PCM also supplies the ground path, or sensor return circuit, from the sensor. These power and ground circuits are also connected to the crankshaft position sensor. If a problem is detected in the camshaft position circuit, a DTC will set.

On 3.8L engine, the Camshaft Position (CMP) sensor is mounted on the engine timing chain front cover. The camshaft position sensor sends a cam signal to the PCM which uses it as a sync pulse to trigger the injectors in the proper sequence. The CAM signal is passed through the ignition control module. The PCM uses the CAM signal to indicate the position of the #1 piston during its power stroke, allowing the PCM to calculate true Sequential Fuel Injection. If the PCM detects an incorrect CAM signal, a DTC will set.

Removal & Installation



3.1L & 3.4L (VIN E) Engines

Specific to:

Buick Century 1997-2000

Buick Regal 1997-2000

Chevrolet Lumina 1997-2000

Chevrolet Monte Carlo 1997-2000

Oldsmobile Cutlass Supreme 1997

Oldsmobile Intrigue 1998-2000

Pontiac Grand Prix 1997-2000



Click image to see an enlarged view

Fig. Camshaft Position (CMP) sensor removal-3.1L and 3.4L (VIN E) engines

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the serpentine drive belt, as outlined in Section 1 of this manual.
  4.  
  5. Remove the power steering pump assembly and set aside with the lines attached.
  6.  
  7. Detach the CMP sensor electrical connector.
  8.  
  9. Unfasten the retainer bolt, then remove the CMP sensor.
  10.  
  11. Installation is the reverse of the removal procedure.
  12.  

3.4L (VIN X) Engine

Specific to:

Buick Century 1997-2000

Buick Regal 1997-2000

Chevrolet Lumina 1997-2000

Chevrolet Monte Carlo 1997-2000

Oldsmobile Cutlass Supreme 1997

Oldsmobile Intrigue 1998-2000

  1. Disconnect the negative battery cable.
  2.  
  3. Detach the electrical connector from the camshaft position sensor.
  4.  
  5. Remove the sensor retainer bolt and carefully pull the sensor from the camshaft carrier. An O-ring seal may hold the sensor in place. Use care not to lose the O-ring.
  6.  



Click image to see an enlarged view

Fig. Camshaft Position (CMP) sensor removal-3.4L (VIN X) engine

To install:

  1. Installation is the reverse of the removal procedure.
  2.  
  3. Before installing a replacement camshaft sensor, lubricate the new O-ring with clean engine oil. Tighten the bolt to just 88 inch lbs. (10 Nm). Do not over-tighten.
  4.  
  5. Connect the negative battery cable.
  6.  

3.5L (VIN H) Engine

Specific to:

Buick Century 1997-2000

Buick Regal 1997-2000

Chevrolet Lumina 1997-2000

Chevrolet Monte Carlo 1997-2000

Oldsmobile Cutlass Supreme 1997

Oldsmobile Intrigue 1998-2000

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the two coolant recovery tank mounting nuts and lift out the tank to gain access to the camshaft position sensor.
  4.  
  5. Detach the electrical connector from the camshaft position sensor.
  6.  



Click image to see an enlarged view

Fig. Camshaft Position Sensor removal-3.5L VIN H Engine

  1. Remove the retaining screw. Remove the sensor by pulling on the sensor connector. Do not pry on the bracket. Do not rotate (twist) the sensor or damage the mounting bracket, if the sensor is to be reused.
  2.  

To install:

  1. Installation is the reverse of the removal process, observing the following points:
    1. Make sure the sensor bore is completely free of any foreign material (old O-ring, dirt, burrs, etc.).
    2.  
    3. Make sure that the flange of the sensor bore is not damaged.
    4.  
    5. Clean all mounting surfaces before reinstalling any components.
    6.  
    7. If the sensor is being reused, check for damage. Inspect the face of the sensor (bottom of the brass housing) for damage.
    8.  
    9. Never install a sensor that has been dropped.
    10.  
    11. Lubricate the O-ring with clean engine oil.
    12.  

  2.  
  3. Install the camshaft position sensor and fully seat into its bore. Install the retaining screw and torque to just 80 inch lbs. (9 Nm). Do not over-tighten. Verify the electrical connector is secure.
  4.  
  5. Install the coolant recovery tank, then connect the negative battery cable.
  6.  

3.8L Engines

Specific to:

Buick Century 1997-2000

Buick Regal 1997-2000

Chevrolet Lumina 1997-2000

Chevrolet Monte Carlo 1997-2000

Oldsmobile Cutlass Supreme 1997

Oldsmobile Intrigue 1998-2000

Pontiac Grand Prix 1997-2000

  1. Disconnect the negative battery cable.
  2.  
  3. Detach the electrical connector from the camshaft position sensor.
  4.  



Click image to see an enlarged view

Fig. Camshaft Position Sensor removal-3.8L Engines

  1. Remove the retaining screw and separate the sensor from the front cover.
  2.  

To install:

  1. Installation is the reverse of the removal process.
  2.  
  3. Tighten the bolt to just 44 inch lbs. (5 Nm). Do not over-tighten. Verify the electrical connector is secure.
  4.  
  5. Connect the negative battery cable.
  6.  

Testing



Specific to:

Buick Century 1997-2000

Buick Regal 1997-2000

Chevrolet Lumina 1997-2000

Chevrolet Monte Carlo 1997-2000

Oldsmobile Cutlass Supreme 1997

Oldsmobile Intrigue 1998-2000

Pontiac Grand Prix 1997-2000

Perform the following checks before getting into more complicated diagnosis and repair.



Some faults in the CMP circuit can be the result of secondary ignition components leaking high voltage into the ignition module. Check for incorrect harness routing too near secondary ignition components. Examine the ignition coils for signs of coil arcing to the wiring harness or to the ICM. Check the coils for cracks, carbon tracking or other signs of damage. Check the secondary wiring (spark plug wires) for arcing to the wiring harness.
 
An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation.
 
Inspect for a faulty coil.
 
Inspect for poor connections. Check the PCM harness and connectors for improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connection.
 
Look for a damaged harness or damaged wiring going to the CMP sensor, especially if heavy work has recently been done where the connector could have been damaged.
 


NOTE
The best method to test this sensor is with the use of an oscilloscope.

  1. Visually check the connector, making sure it is connected properly and all of the terminals are straight, tight and free of corrosion.
  2.  
  3. With the ignition in the ON position, check the sensor voltage using an oscilloscope. When the starter is briefly operated, a square wave pattern, alternating from 0-12 volts should be seen at terminal A. If the voltage is within specification, the sensor is functional.
  4.  

 
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