BMW Cars 1999-06

Crankshaft Position Sensor

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Refer to Electronic Engine Controls in Section 4 for information on servicing the Crankshaft Position (CKP) Sensor.

Operation



The Crankshaft Position (CKP) sensor/engine speed sensor provides the Engine Control Module (ECM) unit with engine speed information. The sensor reads the information from a toothed wheel mounted on or integral with the crankshaft.

The S14 engines' speed sensor is mounted next to the cylinder identifying sensor on the bell housing and uses the teeth of the flywheel's ring gear for calculating the engine speed.

The M20, M42, M50 and S50 engines up to and including 1995 vehicles (OBD I) have the CKP sensor/speed sensor mounted on the front engine cover and reads a toothed wheel mounted to the crankshaft pulley.

On all 1996-98 models (OBD II compliant), the CKP sensor is mounted into the lower left rear portion of the engine block and reads a toothed wheel mounted to the end of the crankshaft assembly.

If the Engine Control Module (ECM) does not receive a signal from the Crankshaft Position (CKP) when the engine is cranked, the engine will not start.



Click image to see an enlarged view

Fig. The Crankshaft Position (CKP) sensor is located just below the starter motor and mounted into the engine block-M44 engine shown

The crankshaft sensor is a dynamic hall-effect sensor (mounted through a access hole in the engine block). A signal is sent to the DME the moment the crankshaft begins to rotate. The pulse wheel is mounted directly to the crankshaft.

The crankshaft sensor is a dynamic hall-effect sensor (mounted through a access hole in the engine block). A signal is sent to the DME the moment the crankshaft begins to rotate. The pulse wheel is mounted directly to the crankshaft.

The crankshaft sensor is a dynamic hall-effect sensor (mounted through a access hole in the engine block). A signal is sent to the DME the moment the crankshaft begins to rotate. The pulse wheel is mounted directly to the crankshaft.

The crankshaft sensor is a dynamic hall-effect sensor (mounted through a access hole in the engine block). A signal is sent to the DME the moment the crankshaft begins to rotate. The pulse wheel is mounted directly to the crankshaft.

The crankshaft sensor is a dynamic hall-effect sensor (mounted through a access hole in the engine block). A signal is sent to the DME the moment the crankshaft begins to rotate. The pulse wheel is mounted directly to the crankshaft.

The crankshaft sensor is a dynamic hall-effect sensor (mounted through a access hole in the engine block). A signal is sent to the DME the moment the crankshaft begins to rotate. The pulse wheel is mounted directly to the crankshaft.

The crankshaft sensor is a dynamic hall-effect sensor (mounted through a access hole in the engine block). A signal is sent to the DME the moment the crankshaft begins to rotate. The pulse wheel is mounted directly to the crankshaft.

The crankshaft sensor is a dynamic hall-effect sensor (mounted through a access hole in the engine block). A signal is sent to the DME the moment the crankshaft begins to rotate. The pulse wheel is mounted directly to the crankshaft.

The crankshaft sensor is a dynamic hall-effect sensor (mounted through a access hole in the engine block). A signal is sent to the DME the moment the crankshaft begins to rotate. The pulse wheel is mounted directly to the crankshaft.

The crankshaft sensor is a dynamic hall-effect sensor (mounted through a access hole in the engine block). A signal is sent to the DME the moment the crankshaft begins to rotate. The pulse wheel is mounted directly to the crankshaft.

The crankshaft sensor is a dynamic hall-effect sensor (mounted through a access hole in the engine block). A signal is sent to the DME the moment the crankshaft begins to rotate. The pulse wheel is mounted directly to the crankshaft.

The crankshaft sensor is a dynamic hall-effect sensor (mounted through a access hole in the engine block). A signal is sent to the DME the moment the crankshaft begins to rotate. The pulse wheel is mounted directly to the crankshaft.

The crankshaft sensor is a dynamic hall-effect sensor (mounted through a access hole in the engine block). A signal is sent to the DME the moment the crankshaft begins to rotate. The pulse wheel is mounted directly to the crankshaft.

The crankshaft sensor is a dynamic hall-effect sensor (mounted through a access hole in the engine block). A signal is sent to the DME the moment the crankshaft begins to rotate. The pulse wheel is mounted directly to the crankshaft.

The crankshaft sensor is a dynamic hall-effect sensor (mounted through a access hole in the engine block). A signal is sent to the DME the moment the crankshaft begins to rotate. The pulse wheel is mounted directly to the crankshaft.

The crankshaft sensor is a dynamic hall-effect sensor (mounted through a access hole in the engine block). A signal is sent to the DME the moment the crankshaft begins to rotate. The pulse wheel is mounted directly to the crankshaft.

Removal & Installation



  1. Turn the ignition switch OFF .
  2.  
  3. On late model M42 engines and M44 engines, remove the upper intake manifold to access the CKP sensor connector.
  4.  
  5. Detach the CKP sensor connector.
  6.  
  7. Unscrew the bolt holding the sender to the engine. Withdraw the sender from the engine.
  8.  
  9. Unclip the electrical leads as necessary from the lead guide and remove sender from the vehicle.
  10.  

To install:

  1. On rear engine block mounted sensors, install a new O-ring when installing the sensor.
  2.  
  3. Install the sensor onto the engine making sure the sensor is properly seated. Tighten the mounting bolts to 4.5-5.5 ft. lbs. (6-8 Nm).
  4.  
  5. On front mounted sensors, check the air gap and adjust to 0.030-0.050 inches (0.7-1.3mm)
  6.  
  7. Replace the lead in the lead guide as necessary and plug in the connector. Make sure that the lead will not rub on the drive belt.
  8.  
  9. If the upper intake manifold was removed, reinstall the manifold as outlined in Section 3.
  10.  

Testing



Use a BMW service tester, the OBD I blink code or on OBD II vehicles, use a suitable Data Scan Tool (DST) to check for faults and/or if capable, to read the values of the components. If this diagnostic equipment is not available, proceed as follows.


WARNING
When checking component values (volts or ohms) a suitable digital volt/ohmmeter must be used otherwise the circuit and/or component may be damaged.

M20 & S14 Engines

The engine speed sensor provides the DME unit with engine speed information. The sensor reads the information from a tooth wheel mounted on the crankshaft hub except on the S14 engine. It can also be called the crankshaft sensor.

The S14 engines speed sensor is mounted next to the cylinder identifying sensor and is removed in the same manner as the cylinder identifying sensor. The sensor on the S14 engine connects to a plug mounted in a group of 3 plugs on the engine compartment rear wall, next to the engine harness connector and diagnostic socket. It is the connector on the right side.

  1. Turn the ignition switch to the OFF position.
  2.  
  3. Trace the sensor lead back to the connector and disconnect.
  4.  
  5. Check the resistance between terminals 1 and 2. The resistance should be 490-590 ohms.
  6.  

M42, M44, M50, S50, M52, S52 Engines
Engine Block Mounted Sensors

On engine block mounted Crankshaft Position (CKP) sensors, the sensor is located just below the starter motor.

  1. On late model M42 engines and M44 engines, remove the upper intake manifold as outlined in Section 3 to access the sensor connector.
  2.  
  3. Detach the CKP sensor connector.
  4.  
  5. Use a digital ohmmeter and measure the resistance between the two outer terminals of the sensor.
  6.  
  7. The measured resistance should be 1,150-1,400 ohms
  8.  



Click image to see an enlarged view

Fig. Using a suitable scan tool really does help save time. To access the crankshaft and camshaft sensors connectors on late M42 engines and all M44 engines, you must remove the upper intake manifold

Front Mounted Sensors

On front mounted Crankshaft Position (CKP) sensors:

  1. Detach the CKP sensor connector.
  2.  
  3. Use a digital ohmmeter and measure the resistance between the two outer terminals of the sensor.
  4.  
  5. The measured resistance should be 1,150-1,400 ohms
  6.  

 
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