GM Lumina/Grand Prix/Cutlass Supreme/Regal 1988-1996

Camshaft Position (CMP) Sensor

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OPERATION



The ECM uses the camshaft signal to determine the position of the No. 1 cylinder piston during its power stroke. The signal is used by the ECM 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.

TESTING



See Figures 1, 2 and 3

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Fig. Fig. 1: Camshaft Position (CMP) and Crankshaft Position (CKP) sensor wiring diagram-3.1L (VIN M) engine



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Fig. Fig. 2: Camshaft Position (CMP) and Crankshaft Position (CKP) sensor wiring diagram 1995-96 3.4L engine



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Fig. Fig. 3: Camshaft Position (CMP) and Crankshaft Position (CKP) sensor wiring digrams - 1995-96 3.8L engine

  1. Disconnect the CMP sensor wiring harness and connect an LED test light between CMP harness terminal C and battery ground.
  2.  
  3. With the ignition ON and the engine OFF, verify that the test light illuminates.
  4.  
  5. If not as specified, repair or replace the fuse and/or wiring.
  6.  
  7. Carefully connect the test light between CMP harness terminal A and C and verify that the test light illuminates.
  8.  
  9. If not as specified, repair the CMP harness ground circuit (terminal A ).
  10.  
  11. Turn the ignition OFF and disconnect the test light.
  12.  
  13. Next, connect suitable jumper wires between the CMP sensor and CMP sensor harness. Connect a DC volt meter to the jumper wire corresponding to CMP terminal B and battery ground.
  14.  
  15. Start the engine and verify that the voltage signal is 5-7 volts.
  16.  
  17. If it is not as specified, the CMP sensor may be faulty.
  18.  

REMOVAL & INSTALLATION



3.1L and 3.8L Engines

See Figure 4 and 5



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Fig. Fig. 4: Camshaft Position (CMP) sensor mounting-1995 3.1L engine shown



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Fig. Fig. 5: Camshaft Position (CMP) sensor location-1995 3.8L engine shown

On the 3.1L and 3.8L engines, the CMP sensor is located on the timing cover, behind the water pump, near the camshaft sprocket.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the serpentine drive belt.
  4.  
  5. Remove the power steering pump, as outlined in Suspension & Steering of this repair guide.
  6.  
  7. Detach the sensor electrical connector.
  8.  
  9. Remove the CMP sensor mounting bolt, then remove the sensor from the engine.
  10.  
  11. Inspect the sensor O-ring seal and replace as required.
  12.  

To install:
  1. Position the CMP sensor and secure with the retaining bolt. Tighten the bolt to 8 ft. lbs. (10 Nm).
  2.  
  3. Attach the sensor electrical connector.
  4.  
  5. Install the power steering pump, as outlined in Suspension & Steering of this repair guide.
  6.  
  7. Install the serpentine drive belt.
  8.  
  9. Connect the negative battery cable.
  10.  

3.4L Engine

See Figure 6



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Fig. Fig. 6: On the 3.4L engine, the CMP sensor is located on the top of the cylinder head towards the #3 cylinder

  1. Disconnect the negative battery cable.
  2.  
  3. Detach the electrical connector from the sensor.
  4.  
  5. Unfasten the CMP sensor mounting bolt, then remove the sensor from the engine.
  6.  
  7. Inspect the O-ring seal and replace as required.
  8.  

To install:
  1. Position the CMP sensor and secure with the retaining bolt. Tighten the bolt to 8 ft. lbs. (10 Nm).
  2.  
  3. Attach the sensor electrical connector.
  4.  
  5. Connect the negative battery cable.
  6.  

 
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