Ram B1500, B2500, B3500, 1999-2003

Crankshaft Position Sensor

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Operation



The CKP sensor, located on the back of the engine, runs off the flywheel/driveplate and provides the ECM with crankshaft position and engine speed. The sensor is a Hall effect type that senses the passing of teeth on a flywheel/driveplate, because the teeth disrupt the magnetic field of the sensor. This disruption creates a pulse generation, which is monitored by the ECM.

On the 3.9L engine, the flywheel/driveplate has three sets of double notches and three sets of single notches. On the 5.2L and the 5.9L, the flywheel/driveplate has eight single notches spaced every 45 degrees. The ECM uses these pulses to properly set the ignition timing. With out these signals, the vehicles will crank but not start.

Click image to see an enlarged view

Fig.



Click image to see an enlarged view

Fig.

The CKP sensor, located on the back of the engine, runs off the flywheel/driveplate and provides the ECM with crankshaft position and engine speed. The sensor is a Hall effect type that senses the passing of teeth on a flywheel/driveplate, because the teeth disrupt the magnetic field of the sensor. This disruption creates a pulse generation, which is monitored by the ECM.

On the 3.9L engine, the flywheel/driveplate has three sets of double notches and three sets of single notches. On the 5.2L and the 5.9L, the flywheel/driveplate has eight single notches spaced every 45 degrees. The ECM uses these pulses to properly set the ignition timing. With out these signals, the vehicles will crank but not start.

Click image to see an enlarged view

Fig.



Click image to see an enlarged view

Fig.

The crankshaft position sensor generates pulses and sends them to the PCM. The PCM interprets this input signal to determine the crankshaft position (and engine speed). With this and other information, the engine controller determines injector sequence and ignition timing. The sensor is a hall-effect device combined with an internal magnet. It is sensitive to steel within a certain distance from it.

On the 4-cylinder engine, the crankshaft position sensor is mounted to the transmission bell housing. On the V6 and V8 engines, the crankshaft position sensor is bolted to the cylinder block near the rear of the right cylinder head. On the V10 engine, the crankshaft position sensor is located on the right-lower side of the cylinder block, just above the oil pan rail



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Fig. Crankshaft position sensor location-typical



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Fig. Crankshaft position sensor-8.0L engine



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Fig. Operation of the crankshaft position sensor-typical

Removal & Installation



Except V-10 Engine
  1. Remove the air cleaner assembly if necessary for access to the sensor.
  2.  
  3. Disconnect the pigtail harness from the sensor.
  4.  
  5. Remove the nut holding the sensor wire clip to the fuel rail mounting stud.
  6.  
  7. Remove the sensor mounting hardware, then the sensor.
  8.  
  9. Remove the clip from the sensor wire harness.
  10.  

To install:

  1. Install the sensor flush against the opening.
  2.  
  3. Install and tighten the bolts or nuts, as applicable.
  4.  
  5. Install the electrical connector.
  6.  
  7. Install the clip on the sensor wire harness.
  8.  
  9. Install the clip over the fuel rail mounting stud. Install the clip mounting nut.
  10.  

V10 Engine
  1. Raise and safely support the vehicle.
  2.  
  3. Unplug the sensor harness connector from the engine harness.
  4.  
  5. Remove the sensor mounting bolt.
  6.  
  7. Carefully pry the sensor from the timing chain case/cover in a rocking action with two small prytools.
  8.  
  9. Remove the sensor. Check the condition of the sensor O-ring.
  10.  

To install:

  1. Apply a small amount of fresh engine oil to the sensor O-ring.
  2.  
  3. Using a slight rocking action, install the sensor into the timing case/cover until the paper spacer just contacts the gear. Do NOT twist the sensor or you may tear the O-ring.
  4.  
  5. Install the mounting bolt, tightening it to 70 inch lbs. (8 Nm).
  6.  
  7. Connect the sensor wiring.
  8.  



Click image to see an enlarged view

Fig. CKP sensor's wiring: (1) GY/BK (sensor signal), (2) BK/LB (sensor ground), (3) OR (5v supply)

Testing




WARNING
Testing the wiring harness with the ECM still connected can cause serious damage to the processor. ALWAYS disconnect the ECM before Testing the wiring harness., unless instructed otherwise.

  1. Remove the engine cover.
  2.  
  3. Using the DRB-II scan tool or equivalent, plug into diagnostic connector and erase DTCs.
  4.  
  5. Turn ignition OFF and then ON again.
  6.  
  7. Crank engine until starts or for 10 seconds, whichever first. Monitor Crank Signal on scan tool. If Crank Signal is detected, CKP sensor is OK, if No Crank Signal is detected, proceed with diagnostics.
  8.  
  9. Inspect wiring and connectors and repair as necessary and retest. If the wiring and connectors are OK, proceed to the next step.
  10.  
  11. With the ignition OFF, unplug the CKP sensor signal. Using a voltmeter, check the supply voltage using supplied schematics.
  12.  
  13. On 1995 and earlier vehicles, it should be 7.0v or more; if not, repair circuit and retest. If voltage is OK, proceed to next step.
  14.  
  15. On 1996-98 vehicles, it should be 4.5v or more; if not, repair circuit and retest. If voltage is OK, proceed to the next step.
  16.  
  17. Using the scan tool, erase DTCs in the ECM, then turn the ignition OFF and install a jumper wire on the CKP signal circuit. Turn the ignition ON.
  18.  
  19. While observing the display on scan tool, tap the other end of the jumper wire to the sensor ground. If the scan tool shows No Cam Sync, replace the CKP sensor. If the scan tool shows a Cam Sync, proceed to next step.
  20.  
  21. With the ignition OFF, using an ohmmeter probe the ground signal on the CKP sensor connector, measure the resistance between the connector and ground. If it is less than 5.0 ohms, proceed to the next step; if it is more than 5.0v, repair the circuit and retest.
  22.  
  23. Disconnect the negative battery cable.
  24.  
  25. Disconnect the ECM wiring harness. Inspect for any damaged pins or connector terminals and repair and retest if necessary.
  26.  
  27. Using an ohmmeter, test the CKP signal circuit between CKP connector and ECM connector for resistance. If it is less than 5.0 ohms, proceed to next step, if it is more than 5.0 ohms, repair the circuit and retest.
  28.  
  29. Plug in the CKP sensor connector.
  30.  
  31. Using an ohmmeter, measure the resistance between the CKP signal circuit and CKP ground at the ECM connector. If resistance is less than 5ohms, repair the short in the CKP signal wire. If the resistance is more than 5 ohms, replace the CKP sensor.

    Click image to see an enlarged view

    Fig.

  32.  


WARNING
Testing the wiring harness with the ECM still connected can cause serious damage to the processor. ALWAYS disconnect the ECM before Testing the wiring harness., unless instructed otherwise.

  1. Remove the engine cover.
  2.  
  3. Using the DRB-II scan tool or equivalent, plug into diagnostic connector and erase DTCs.
  4.  
  5. Turn ignition OFF and then ON again.
  6.  
  7. Crank engine until starts or for 10 seconds, whichever first. Monitor Crank Signal on scan tool. If Crank Signal is detected, CKP sensor is OK, if No Crank Signal is detected, proceed with diagnostics.
  8.  
  9. Inspect wiring and connectors and repair as necessary and retest. If the wiring and connectors are OK, proceed to the next step.
  10.  
  11. With the ignition OFF, unplug the CKP sensor signal. Using a voltmeter, check the supply voltage using supplied schematics.
  12.  
  13. On 1995 and earlier vehicles, it should be 7.0v or more; if not, repair circuit and retest. If voltage is OK, proceed to next step.
  14.  
  15. On 1996-98 vehicles, it should be 4.5v or more; if not, repair circuit and retest. If voltage is OK, proceed to the next step.
  16.  
  17. Using the scan tool, erase DTCs in the ECM, then turn the ignition OFF and install a jumper wire on the CKP signal circuit. Turn the ignition ON.
  18.  
  19. While observing the display on scan tool, tap the other end of the jumper wire to the sensor ground. If the scan tool shows No Cam Sync, replace the CKP sensor. If the scan tool shows a Cam Sync, proceed to next step.
  20.  
  21. With the ignition OFF, using an ohmmeter probe the ground signal on the CKP sensor connector, measure the resistance between the connector and ground. If it is less than 5.0 ohms, proceed to the next step; if it is more than 5.0v, repair the circuit and retest.
  22.  
  23. Disconnect the negative battery cable.
  24.  
  25. Disconnect the ECM wiring harness. Inspect for any damaged pins or connector terminals and repair and retest if necessary.
  26.  
  27. Using an ohmmeter, test the CKP signal circuit between CKP connector and ECM connector for resistance. If it is less than 5.0 ohms, proceed to next step, if it is more than 5.0 ohms, repair the circuit and retest.
  28.  
  29. Plug in the CKP sensor connector.
  30.  
  31. Using an ohmmeter, measure the resistance between the CKP signal circuit and CKP ground at the ECM connector. If resistance is less than 5ohms, repair the short in the CKP signal wire. If the resistance is more than 5 ohms, replace the CKP sensor.

    Click image to see an enlarged view

    Fig.

  32.  

On the 2.5L engine, the Crankshaft Position (CMK) sensor is located near the outer edge of the flywheel (or starter ring gear). On other models it is fitted to the right side of the engine block.

The only test you can perform without a DRBII scan tool, or equivalent, is a basic check of the sensor only.

  1. Disconnect the sensor harness connector from the main wire harness connector.
  2.  
  3. Place an ohmmeter across terminals 1 and 2 (see the illustration). The meter reading should be open (infinite resistance). If a low resistance is read, replace the camshaft position sensor.
  4.  

 
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