Liberty, Wrangler, 1997-2005

Camshaft Position Sensor

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Description & Operation



2.4L

The Camshaft Position Sensor (CMP) sensor contains a hall effect device referred to as a sync signal generator. A rotating target wheel (tone wheel) for the CMP is located behind the exhaust valve-camshaft drive gear. The target wheel is equipped with a cutout (notch) around 180 degrees of the wheel. The CMP detects this cutout every 180 degrees of camshaft gear rotation. Its signal is used in conjunction with the Crankshaft Position Sensor (CKP) to differentiate between fuel injection and spark events. It is also used to synchronize the fuel injectors with their respective cylinders.

When the leading edge of the target wheel cutout enters the tip of the CMP, the interruption of magnetic field causes the voltage to switch high, resulting in a sync signal of approximately 5 volts. When the trailing edge of the target wheel cutout leaves the tip of the CMP, the change of magnetic field causes the sync signal voltage to switch low to 0 volts.

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Fig.



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Fig.

2.5L Engines

On the 2.5L 4cylinder engine the Camshaft Position (CMP) sensor is located in the distributor.

The sensor contains a Hall effect device called a sync signal generator to generate a fuel sync signal. This sync signal generator detects a rotating pulse ring (shutter) on the distributor shaft. The pulse ring rotates 180 degrees through the sync signal generator. Its signal is used in conjunction with the Crankshaft Position (CKP) sensor to differentiate between fuel injection and spark events. It is also used to synchronize the fuel injectors with their respective cylinders.

When the leading edge of the pulse ring (shutter) enters the sync signal generator, the following occurs: The interruption of magnetic field causes the voltage to switch high resulting in a sync signal of approximately 5 volts. When the trailing edge of the pulse ring (shutter) leaves the sync signal generator, the following occurs: The change of the magnetic field causes the sync signal voltage to switch low to 0 volts.

Click image to see an enlarged view

Fig.

3.7L

The Camshaft Position Sensor (CMP) sensor contains a hall effect device referred to as a sync signal generator. A rotating target wheel (tone wheel) for the CMP is located at the front of the camshaft for the right cylinder head. This sync signal generator detects notches located on a tone wheel. As the tone wheel rotates, the notches pass through the sync signal generator. The signal from the CMP sensor is used in conjunction with the Crankshaft Position Sensor (CKP) to differentiate between fuel injection and spark events. It is also used to synchronize the fuel injectors with their respective cylinders.

When the leading edge of the target wheel notch enters the tip of the CMP, the interruption of magnetic field causes the voltage to switch high, resulting in a sync signal of approximately 5 volts. When the trailing edge of the target wheel notch leaves then tip of the CMP the change of the magnetic field causes the sync signal voltage to switch to 0 volts.

Click image to see an enlarged view

Fig.



Click image to see an enlarged view

Fig.

4.0L

The Camshaft Position Sensor (CMP) on the 4.0L 6cylinder engine is bolted to the top of the oil pump drive shaft assembly. The sensor and drive shaft assembly is located on the right side of the engine near the oil filter.

The CMP sensor contains a Hall effect device called a sync signal generator to generate a fuel sync signal. This sync signal generator detects a rotating pulse ring (shutter) on the oil pump drive shaft. The pulse ring rotates 180 degrees through the sync signal generator. Its signal is used in conjunction with the crankshaft position sensor to differentiate between fuel injection and spark events. It is also used to synchronize the fuel injectors with their respective cylinders.

When the leading edge of the pulse ring (shutter) enters the sync signal generator, the following occurs: The interruption of magnetic field causes the voltage to switch high resulting in a sync signal of approximately 5 volts.

When the trailing edge of the pulse ring (shutter) leaves the sync signal generator, the following occurs: The change of the magnetic field causes the sync signal voltage to switch low to 0 volts.

Click image to see an enlarged view

Fig.

4.7L

The Camshaft Position Sensor (CMP) on the 4.7L V8 engine is bolted to the front/top of the right cylinder head.

The CMP sensor contains a Hall effect device called a sync signal generator to generate a fuel sync signal. This sync signal generator detects notches located on a tone wheel. The tone wheel is located at the front of the camshaft for the right cylinder head. As the tone wheel rotates, the notches pass through the sync signal generator. The pattern of the notches (viewed counter-clockwise from front of engine) is: 1 notch, 2 notches, 3 notches, 3 notches, 2 notches 1 notch, 3 notches and 1 notch. The signal from the CMP sensor is used in conjunction with the crankshaft position sensor to differentiate between fuel injection and spark events. It is also used to synchronize the fuel injectors with their respective cylinders.

Click image to see an enlarged view

Fig.

5.7L V8 Engines

The Camshaft Position Sensor (CMP) on the 5.7L V-8 engine is located below the generator on the timing chain / case cover on the right/front side of engine.

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Fig.

The CMP sensor is used in conjunction with the crankshaft position sensor to differentiate between fuel injection and spark events. It is also used to synchronize the fuel injectors with their respective cylinders. The sensor generates electrical pulses. These pulses (signals) are sent to the Powertrain Control Module (PCM). The PCM will then determine crankshaft position from both the camshaft position sensor and crankshaft position sensor.

The tone wheel is located at the front of the camshaft (2). As the tone wheel rotates, notches (3) pass through the sync signal generator.

When the cam gear is rotating, the sensor will detect the notches. Input voltage from the sensor to the PCM will then switch from a low (approximately 0.3 volts) to a high (approximately 5 volts). When the sensor detects a notch has passed, the input voltage switches back low to approximately 0.3 volts.

Removal & Installation



2.4L Engines

The Camshaft Position Sensor (CMP) on the 2.4L 4cylinder engine is bolted to the right-front side of the cylinder head. Sensor position (depth) is adjustable.

  1. Disconnect electrical connector at CMP sensor.
  2.  
  3. Remove 2 sensor mounting bolts.
  4.  
  5. Remove sensor from cylinder head by sliding towards rear of engine.
  6.  

To install:

  1. Remove plastic, upper timing belt cover (timing gear cover) by removing 3 bolts. Before attempting to remove cover, remove electrical connector from Engine Coolant Temperature (ECT) sensor. This will prevent damage to sensor.
  2.  
  3. Rotate (bump over) engine until camshaft timing gear and target wheel (tone wheel) are positioned and aligned to face of sensor.
    WARNING
    If gear and tone wheel are not properly positioned, damage to both sensor and target wheel will occur when attempting to start engine. Face of sensor MUST be behind target wheel while adjusting.

  4.  
  5. Position sensor to cylinder head and install 2 sensor mounting bolts finger tight.
  6.  
  7. Set air gap between rear of target wheel and face of sensor to .030. This can best be accomplished using an L-shaped, wire-type spark plug gapping gauge. A piece of .030 brass shim stock may also be used.
  8.  
  9. Gently push sensor forward until it contacts gapping gauge. Do not push hard on sensor. Tighten 2 sensor mounting bolts.
    WARNING
    After tightening sensor mounting bolts, recheck air gap and adjust as necessary. Retorque bolts.

  10.  
  11. Install upper timing belt cover and 3 bolts.
  12.  
  13. Connect electrical connector to ECT sensor.
  14.  
  15. Connect electrical connector to CMP sensor.
  16.  

2.5L

On 2.5L engines, the camshaft position sensor is located in the distributor. Distributor Removal & Installation is not necessary to remove camshaft position sensor.

  1. Disconnect negative battery cable at battery.
  2.  
  3. Remove distributor cap from distributor (two screws).
  4.  
  5. Disconnect camshaft position sensor wiring harness from main engine wiring harness.
  6.  
  7. Remove distributor rotor from distributor shaft.
  8.  
  9. Lift camshaft position sensor assembly from distributor housing.
  10.  

To install:

  1. On 2.5L engines, the camshaft position sensor is located in the distributor.
  2.  
  3. Install camshaft position sensor to distributor. Align sensor into notch on distributor housing.
  4.  
  5. Connect wiring harness.
  6.  
  7. Install rotor.
  8.  
  9. Install distributor cap. Tighten mounting screws.
  10.  

3.7L

The Camshaft Position Sensor (CMP) on this engine is bolted to the front/top of the right cylinder head.

  1. Disconnect electrical connector at CMP sensor.
  2.  
  3. Remove sensor mounting bolt.
  4.  
  5. Carefully remove sensor from cylinder head in a rocking and twisting action. Twisting sensor eases Removal & Installation.
  6.  
  7. Check condition of sensor O-ring.
  8.  

To install:

  1. Clean out machined hole in cylinder head.
  2.  
  3. Apply a small amount of engine oil to sensor O-ring.
  4.  
  5. Install sensor into cylinder head with a slight rocking and twisting action.
    WARNING
    Before tightening sensor mounting bolt, be sure sensor is completely flush to cylinder head. If sensor is not flush, damage to sensor mounting tang may result.

  6.  
  7. Install mounting bolt and tighten.
  8.  
  9. Connect electrical connector to sensor.
  10.  

The Camshaft Position Sensor (CMP) on this engine is bolted to the front/top of the right cylinder head.

  1. Clean out machined hole in cylinder head.
  2.  
  3. Apply a small amount of engine oil to sensor O-ring.
  4.  
  5. Install sensor into cylinder head with a slight rocking and twisting action.
    WARNING
    Before tightening sensor mounting bolt, be sure sensor is completely flush to cylinder head. If sensor is not flush, damage to sensor mounting tang may result.

  6.  
  7. Install mounting bolt and tighten.
  8.  
  9. Connect electrical connector to sensor.
  10.  

4.0L Engine

The Camshaft Position Sensor (CMP) on the 4.0L 6cylinder engine is bolted to the top of the oil pump drive shaft assembly. The sensor and drive shaft assembly is located on the right side of the engine near the oil filter. The rotational position of oil pump drive determines fuel synchronization only. It does not determine ignition timing.


WARNING
Do NOT attempt to rotate the oil pump drive to modify ignition timing.

  1. Two different procedures are used for Removal & Installation. The first procedure will detail Removal & Installation of the sensor only. The second procedure will detail Removal & Installation of the sensor and oil pump drive shaft assembly. The second procedure is to be used if the engine has been disassembled.
  2.  
  3. An internal oil seal is used in the drive shaft housing that prevents engine oil at the bottom of the sensor. The seal is not serviceable.
  4.  

Sensor Only

  1. Disconnect electrical connector at CMP sensor.
  2.  
  3. Remove 2 sensor mounting bolts.
  4.  
  5. Remove sensor from oil pump drive.
  6.  

Oil Pump Drive & Sensor


WARNING
If the CMP and oil pump drive are to be removed and installed, do NOT allow engine crankshaft or camshaft to rotate. CMP sensor relationship will be lost.

  1. Disconnect electrical connector at CMP sensor.
  2.  
  3. Remove 2 sensor mounting bolts
  4.  
  5. Remove sensor from oil pump drive.
  6.  
  7. Before proceeding to next step, mark and note rotational position of oil pump drive in relationship to engine block. After installation:, the CMP sensor should face rear of engine 0.
  8.  
  9. Remove hold-down bolt and clamp.
  10.  
  11. While pulling assembly from engine, note direction and position of pulse ring. After Removal & Installation, look down into top of oil pump and note direction and position of slot at top of oil pump gear.
  12.  
  13. Remove and discard old oil pump drive-to-engine block gasket.
  14.  

To install:

Sensor Only

The Camshaft Position Sensor (CMP) on the 4.0L 6cylinder engine is bolted to the top of the oil pump drive shaft assembly. The sensor and drive shaft assembly is located on the right side of the engine near the oil filter.

  1. Install sensor to oil pump drive.
  2.  
  3. Install 2 sensor mounting bolts and tighten to 2 Nm (15 inch lbs.) torque.
  4.  
  5. Connect electrical connector to CMP sensor.
  6.  

Oil Pump Drive & Sensor

  1. Clean oil pump drive mounting hole area of engine block.
  2.  
  3. Install new oil pump drive-to-engine block gasket.
  4.  
  5. Temporarily install a toothpick or similar tool through access hole at side of oil pump drive housing. Align toothpick into mating hole on pulse ring.
  6.  
  7. Install oil pump drive into engine while aligning into slot on oil pump. Rotate oil pump drive back to its original position and install hold-down clamp and bolt. Finger-tighten bolt. Do NOT do a final tightening of bolt at this time.
  8.  
  9. If engine crankshaft or camshaft has been rotated, such as during engine tear-down, CMP sensor relationship must be reestablished.
  10.  
  11. Remove ignition coil rail assembly.
  12.  
  13. Remove cylinder number 1 spark plug.
  14.  
  15. Hold a finger over the open spark plug hole. Rotate engine at vibration dampener bolt until compression (pressure) is felt.
  16.  
  17. Slowly continue to rotate engine.
    NOTE
    Do this until timing index mark on vibration damper pulley aligns with top dead center (TDC) mark (0 degree) on timing degree scale. Always rotate engine in direction of normal rotation. Do NOT rotate engine backward to align timing marks.

  18.  
  19. Install oil pump drive into engine while aligning into slot on oil pump. If pump drive will not drop down flush to engine block, the oil pump slot is not aligned. Remove oil pump drive and align slot in oil pump to shaft at bottom of drive. Install into engine. Rotate oil pump drive back to its original position and install hold-down clamp and bolt. Finger-tighten the bolt. Do NOT do a final tightening of bolt at this time.
  20.  
  21. Remove toothpick from housing.
  22.  
  23. Install sensor to oil pump drive. After installation:, the CMP sensor should face rear of engine: 0.
  24.  
  25. Install 2 sensor mounting bolts and tighten to 2 Nm (15 inch lbs.) torque. Connect electrical connector to CMP sensor.
  26.  
  27. If removed, install spark plug and ignition coil rail.
  28.  
  29. To verify correct rotational position of oil pump drive, the DRB scan tool must be used.
    CAUTION
    When performing the following test, the engine will be running. Be careful not to stand in line with the fan blades or fan belt. Do NOT wear loose clothing.

  30.  
  31. Connect the scan tool to data link connector. The data link connector is located in passenger compartment, below and to left of steering column.
  32.  
  33. Gain access to SET SYNC screen on the scan tool.
  34.  
  35. Follow the directions on the scan tool screen and start engine. Bring to operating temperature (engine must be in closed loop mode).
  36.  
  37. With engine running at idle speed, the words IN RANGE should appear on the scan tool screen along with 0. This indicates correct position of oil pump drive.
  38.  
  39. If a plus (+) or a minus (-) is displayed next to degree number, and/or the degree displayed is not zero, loosen, but do NOT remove hold-down clamp bolt. Rotate oil pump drive until IN RANGE appears on screen. Continue to rotate oil pump drive until achieving as close to 0 as possible.
    NOTE
    The degree scale on SET SYNC screen of the scan tool is referring to fuel synchronization only. It is not referring to ignition timing. Because of this, do NOT attempt to adjust ignition timing using this method. Rotating oil pump drive will have no effect on ignition timing. All ignition timing values are controlled by powertrain control module (PCM).

  40.  
  41. Tighten hold-down clamp bolt to 23 Nm (17 ft. lbs.) torque.

    Click image to see an enlarged view

    Fig.



    Click image to see an enlarged view

    Fig.

  42.  

 
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