AutoZone 2007 GMC Truck Envoy Denali 2WD 5.3L SFI OHV 8cyl | Repair Guides | Driveability & Emissions Controls | Electronic Engine Controls | Crankshaft Position (ckp) Sensor | AutoZone.com

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    GM Grand Am/Achieva/Calais/Skylark/Somerset 1985-98

    Crankshaft Position (CKP) Sensor

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    OPERATION



    The crankshaft sensor is sometimes called an engine position sensor, TDC sensor or cylinder sensor. These sensors can be located on the engine (usually near the crankshaft), near the flywheel or inside the distributor.

    Most systems use either a magnetic reluctance type sensor or a Hall effect sensor. These sensors can be differentiated by the number of wires leading to them and the wire function. Normally, magnectic reluctance sensors use two wires. Hall effect sensors use three wires. The first provides power to the sensor. The second is ground. The last wire is the signal back to the control module.

    Magnetic reluctance sensors are combined with a reluctors (toothed wheels). As the reluctor turns the high and low parts of the teeth on the reluctor cause the gap between the sensor and reluctor to change. This change in gap causes the magnetic field near the sensor to change. The control module reads this change in voltage to determine engine speed and crankshaft position. It is interesting to note that a magnetic reluctance sensor generates its own voltage during operation.

    A Hall effect sensor has a metal pulse ring and a pick-up assembly. The can be located either on the engine or inside the distributor. The signal is a digital on/off type signal. When the pulse ring travels through the pickup, a permanent magnet inside the pick-up creates a magnetism which induces voltage. The pulse ring has slots, or one large slot, in the ring which as they pass, the pick-up loses the magnetism and voltage is lost, thus the on/off signal.

    TESTING



    See Figure 1

    Click image to see an enlarged view

    Fig. Fig. 1: Attach suitable jumper wires between the CKP sensor and CKP sensor harness. A DC volt meter can then be attached to the necessary terminals to test the sensor as the engine is being cranked

    Typically, when a crankshaft position sensor DTC is set, checking the integrity of the wiring connecting the sensor (using a digital volt meter) to the PCM harness connector is the best way to determine if the sensor is faulty. If the wires all have continuity, and a DTC is set, it is probable that the sensor is faulty.

    Although a procedure is given here for testing of the crankshaft sensor itself, it is generic, and may not apply to every vehicle. Typically, the crankshaft position sensor harness connector wire leads are labeled. However, it is advisable to use this procedure in conjunction with the wiring diagrams in Chassis Electrical to identify the terminals on the crankshaft sensor before connecting test leads.

    1. Turn the ignition key OFF .
    2.  
    3. Unplug the sensor electrical harness and check the terminals for corrosion and damage.
    4.  
    5. Check the sensor wiring harness wires for continuity and repair as necessary.
    6.  
    7. Attach the sensor harness making sure it is firmly engaged.
    8.  
    9. Using a Digital Volt Ohm Meter (DVOM) set on the DC scale, backprobe the sensor signal terminal (terminal A) with the positive lead of the meter and backprobe the sensor ground terminal (terminal B) with the negative lead of the meter.
    10.  
    11. Have an assistant crank the engine and observe the meter.
    12.  
    13. You should have approximately a 5 volt reference signal pulse. If not the sensor may be defective.
    14.  

    REMOVAL & INSTALLATION



    2.3L Engine

    See Figure 2

    Click image to see an enlarged view

    Fig. Fig. 2: View of the Crankshaft Position (CKP) sensor location and mounting-1995 vehicle shown

    1. Disconnect the negative battery cable.
    2.  
    3. Detach the sensor harness connector at the sensor.
    4.  
    5. Unfasten the retaining bolt, then remove the sensor from the engine.
    6.  

    To install:
    1. Lubricate a new O-ring with clean engine oil, then position it on the sensor.
    2.  
    3. Position the sensor into the hole in the engine block.
    4.  
    5. Install the sensor retaining bolt. Tighten the bolt to 88 inch lbs. (10 Nm).
    6.  
    7. Engage the sensor harness connector.
    8.  
    9. Connect the negative battery cable.
    10.  

    2.4L Engine

    See Figure 3

    Click image to see an enlarged view

    Fig. Fig. 3: Crankshaft position sensor (1) is located next to the oil filter (2) on the 2.4L engine

    1. Disconnect the negative battery cable.
    2.  
    3. Raise the vehicle and support it with jackstands.
    4.  
    5. Unplug the sensor harness connector at the sensor.
    6.  
    7. Unfasten the retaining bolt, then remove the sensor from below the coil pack above the oil filter. Inspect the sensor O-ring for wear, cracks or leakage and replace if necessary.
    8.  

    To install:
    1. Lubricate the O-ring with clean engine oil, then place it on the sensor.
    2.  
    3. Install the sensor and tighten the retaining bolt to and 88 inch lbs. (10 Nm).
    4.  
    5. Attach the sensor harness connector.
    6.  
    7. If removed, install the steering linkage shield.
    8.  
    9. Lower the vehicle.
    10.  
    11. Connect the negative battery cable.
    12.  

    2.5L Engine

    See Figure 4



    Click image to see an enlarged view

    Fig. Fig. 4: Exploded view of the DIS assembly and related components-1987-91 2.5L engine

    1985-86 2.5L engines are equipped with HEI ignition and do not use a crankshaft position sensor.

    1. Disconnect the negative battery cable.
    2.  
    3. Remove the DIS assembly.
    4.  
    5. Remove the sensor retaining screws, then remove the sensor from DIS assembly.
    6.  
    7. Inspect the sensor O-ring for wear, cracks or leakage and replace if necessary.
    8.  

    To install:
    1. Lubricate the crankshaft sensor O-ring with clean engine oil, then install the O-ring on the sensor.
    2.  
    3. Fit the sensor to the DIS assembly, then secure using the retaining screws. Tighten the screws to 20 inch lbs. (2.3 Nm).
    4.  
    5. Install the DIS assembly to the engine.
    6.  
    7. Connect the negative battery cable.
    8.  

    3.0L Engine

    See Figures 5 and 6



    Click image to see an enlarged view

    Fig. Fig. 5: View of the combination sensor which is used on the 3.0L engine



    Click image to see an enlarged view

    Fig. Fig. 6: Combination (crank) sensor mounting-1988 3.0L engine shown

    The combination sensor is only found on the 3.0L engine.

    1. Disconnect the negative battery cable.
    2.  
    3. Remove the right side lower engine compartment filler pane and the right lower wheel house-to-engine compartment bolt.
    4.  
    5. Detach the combination sensor harness connector.
    6.  
    7. Using a 28mm socket and pull handle, rotate the harmonic balancer until any window in the interrupter is aligned with the combination sensor.
    8.  
    9. Loosen the pinch bolt on the sensor pedestal until the sensor is free to slide in the pedestal.
    10.  
    11. While manipulating the sensor within the pedestal, carefully remove the sensor and pedestal as a unit.
    12.  

    To install:
    1. If a new sensor is being installed, loosen the pinch bolt on the new sensor pedestal until the sensor is free to slide in the pedestal.
    2.  
    3. Make sure that the window in the interrupter is still properly positioned, then install the sensor and pedestal as a unit. Be sure that the interrupter ring is aligned with the proper slot.
    4.  
    5. Install the pedestal-to-engine mounting bolts, then tighten them to 22 ft. lbs. (30 Nm).
    6.  
    7. Fasten the lower wheel house-to-engine compartment bolt, then install the right lower filler panel.
    8.  
    9. Connect the negative battery cable.
    10.  

    3.1L Engine
    24X (CKP) Sensor

    See Figure 7

    Click image to see an enlarged view

    Fig. Fig. 7: View of the 24X CKP sensor; this sensor is used on the 3.1L engine only

    1. Disconnect the negative battery cable.
    2.  
    3. Remove the serpentine belt from the crankshaft pulley (harmonic balancer).
    4.  
    5. Raise and safely support the vehicle using jackstands.
    6.  
    7. Unfasten the crankshaft harmonic balancer retaining bolt, then, using special tool J-24420-B or equivalent, remove the balancer.
    8.  
    9. Disengage the sensor electrical connector.
    10.  
    11. Unfasten the sensor retaining bolts, then remove the sensor from the vehicle.
    12.  

    To install:
    1. Install the sensor, then secure using the retaining bolts. Tighten the bolts to 8 ft. lbs. (10 Nm).
    2.  
    3. Engage the sensor electrical connector.
    4.  
    5. Position the balancer on the crankshaft using special tool J-29113 or equivalent. Apply thread sealer 1052080 or equivalent to the retaining bolt threads, then install the bolt and tighten it to 110 ft. lbs. (150 Nm).
    6.  
    7. Carefully lower the vehicle.
    8.  
    9. Install the serpentine belt on the crankshaft pulley.
    10.  
    11. Connect the negative battery cable.
    12.  

    3X (7X) (CKP) Sensor

    See Figure 8



    Click image to see an enlarged view

    Fig. Fig. 8: View of the 3X CKP sensor location and mounting; this sensor is used on the 3.1L engine only

    1. Disconnect the negative battery cable.
    2.  
    3. Remove the starter motor.
    4.  
    5. Detach the sensor harness connector at the module.
    6.  
    7. Unfasten the sensor-to-block retaining bolt, then remove the sensor from the engine.
    8.  
    9. Inspect the sensor O-ring for wear, cracks or leakage and replace if necessary.
    10.  

    To install:
    1. Lubricate the sensor O-ring with clean engine oil, then position it on the sensor.
    2.  
    3. Place the sensor into the hole in the engine block, then install the sensor-to-block bolt. Tighten the retaining bolt to 71 inch lbs. (8 Nm).
    4.  
    5. Attach the sensor harness connector at the module.
    6.  
    7. Install the starter motor. Refer to Engine & Engine Overhaul of this information for details regarding this procedure.
    8.  
    9. Connect the negative battery cable.
    10.  

    3.3L Engine

    See Figures 9, 10 and 11



    Click image to see an enlarged view

    Fig. Fig. 9: View of the harmonic balancer (crankshaft pulley) and location of the interrupter rings-3.3L engine



    Click image to see an enlarged view

    Fig. Fig. 10: Crankshaft Position (CKP) sensor/Dual crank sensor mounting-3.3L engine



    Click image to see an enlarged view

    Fig. Fig. 11: Use a special tool to check the clearance of the harmonic balancer vanes

    1. Disconnect the negative battery cable.
    2.  
    3. Remove the serpentine belt from the crankshaft pulley (harmonic balancer).
    4.  
    5. Raise and safely support support the vehicle.
    6.  
    7. Remove the right front wheel and tire assembly, then remove the inner fender access cover.
    8.  
    9. Using a 28mm socket, disconnect the crankshaft harmonic balancer retaining bolt.
    10.  
    11. Using tool J-38197 or equivalent, remove the harmonic balancer.
    12.  
    13. Disengage the sensor electrical connector.
    14.  
    15. For vehicles through 1992, remove the sensor and pedestal from the engine block face, then separate the sensor from the pedestal.
    16.  
    17. For 1993-94 vehicles, remove the CKP sensor shield. Do NOT use a prybar. Remove the studs and sensor from the block face.
    18.  

    To install:
    1. For vehicles through 1992:
      1. Loosely install the crankshaft sensor to the pedestal.
      2.  
      3. Using tool J-37089 or equivalent, position the sensor with the pedestal attached, on the crankshaft.
      4.  
      5. Install the pedestal-to-block retaining bolts. Tighten and torque to 14-28 ft. lbs. (20-40 Nm).
      6.  
      7. Tighten the pedestal pinch bolt 26-44 inch lbs. (3-5 Nm), then remove tool J-37089 or equivalent.
      8.  

    2.  
    3. For 1993-94 vehicles:
      1. Install the crankshaft position sensor.
      2.  
      3. Install the studs to hold the sensor to the block face, then tighten to 6-9 ft. lbs. (8.5-12 Nm).
      4.  
      5. Install the CKP sensor shield.
      6.  

    4.  
    5. Place tool J-37089 or equivalent, on the harmonic balancer and turn. If any of the harmonic balancer vanes touch the tool, replace the balancer assembly.
    6.  

    A clearance of 0.025 in. (0.635mm) is required on either side of the interrupter ring. Be certain to obtain the correct clearance. Failure to do so will damage the sensor. A misadjusted sensor or bent interrupter ring could cause rubbing of the sensor, resulting in potential driveability problems, such as rough idle, poor performance, or a no start condition.

    1. Install the balancer on the crankshaft. Install the balancer retaining bolt. For vehicles through 1992, tighten the retaining bolt to 200-239 ft. lbs. (270-325 Nm). For 1993-94 vehicles, tighten the retaining bolt to 110 ft. lbs. (149 Nm) plus an additional 76° turn.
    2.  
    3. Install the inner fender shield.
    4.  
    5. Install the right front wheel and tire assembly.
    6.  
    7. Carefully lower the vehicle.
    8.  
    9. Install the serpentine belt.
    10.  
    11. Connect the negative battery cable.
    12.  

     
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