Mazda Trucks 1994-1998 Repair Guide

Camshaft Position (CMP) Sensor

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OPERATION



See Figures 1 and 2

The CMP sensor provides the camshaft position information, called the CMP signal, which is used by the Powertrain Control Module (PCM) for fuel synchronization.

The following vehicles do not utilize a CMP sensor:



1994 B Series Pick-up equipped with 2.3L engine and automatic transmission.
 
1994 B Series Pick-up equipped with 4.0L engine.
 
All 1994-95 MPV models.
 
Navajo models.
 

1994 2.3L engines equipped with a manual transmission, all 1995-97 2.3L and 1998 2.5L engines utilize a CMP sensor that is located on the oil pump cover assembly, on the left-hand lower side of the engine block.

On the 1994 3.0L engine in the B Series Pick-up and 1996-98 MPV, the CMP sensor is an integral component of the distributor assembly, and it is a Hall effect magnetic switch.

On 1995-98 3.0L (B Series Pick-up) and 4.0L engines, the CMP sensor is mounted on an auxiliary shaft drive assembly, located towards the rear of the block. it is also a single hall effect magnetic switch and it is activated by a single vane, and is driven by the camshaft.



Click image to see an enlarged view

Fig. Fig. 1: Camshaft Position (CMP) sensor used on the 2.3L/2.5L engine



Click image to see an enlarged view

Fig. Fig. 2: Typical auxiliary drive mounted Camshaft Position (CMP) sensor used on 3.0L (B Series Pick-up) and 4.0L engines

TESTING



B Series Pick-up Models
THREE WIRE SENSORS

See Figure 3

  1. With the ignition OFF , disconnect the CMP sensor. With the ignition ON and the engine OFF , measure the voltage between sensor harness connector VPWR and PWR GND terminals (refer to the accompanying illustration). If the reading is greater than 10.5 volts, the power circuit to the sensor is okay.
  2.  
  3. With the ignition OFF , install break-out box between the CMP sensor and the PCM. Using a Digital Volt-Ohmmeter (DVOM) set to the voltage function (scale set to monitor less than 5 volts), measure voltage between break-out box terminals 24 and 40 with the engine running at varying RPM. If the voltage reading varies more than 0.1 volt, the sensor is okay.
  4.  



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Fig. Fig. 3: CMP sensor wire harness connections for the 3-wire sensor

TWO WIRE SENSORS

See Figure 4

  1. With the ignition OFF , install a break-out box between the CMP sensor and PCM.
  2.  
  3. Using a Digital Volt-Ohmmeter (DVOM) set to the voltage function (scale set to monitor less than 5 volts), measure the voltage between break-out box terminals 24 and 46 with the engine running at varying RPM. If the voltage reading varies more than 0.1 volt AC, the sensor is okay.
  4.  



Click image to see an enlarged view

Fig. Fig. 4: CMP sensor wire harness connections for the 2-wire sensor

MPV Models

See Figures 5 and 6

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the distributor assembly.
  4.  
  5. Unplug the fuel injector connector.
  6.  
  7. Connect ONLY the distributor 6-pin connector. Do NOT connect the 3-pin connector.
  8.  
  9. Turn the ignition switch to the ON position.
  10.  



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Fig. Fig. 5: Rotate the distributor drive and check the output signal



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Fig. Fig. 6: Output signal specification

  1. Turn the distributor drive by hand and check the output signal.
  2.  
  3. If not as specified, inspect the following:

    Harness continuity between PCM terminal 4G and distributor 6-pin connector terminal D
     
    Harness continuity between PCM terminal 4A and distributor 6-pin connector terminal A
     
    Harness continuity between main relay terminal D and distributor 6-pin connector terminal B
     
    Inspect and measure for battery positive voltage at distributor 6-pin connector terminal B
     

  4.  
  5. If there is incorrect terminal voltage or harness continuity, replace the distributor assembly.
  6.  

REMOVAL & INSTALLATION



2.3L and 2.5L Engines (Except 1994 2.3L Engine With Automatic Transmission)

According to the manufacturer, the A/C system, if equipped, must be discharged for this procedure. Have your A/C system refrigerant reclaimed by an MVAC certified repair shop. However, there may be enough flex or slack in the A/C lines to allow you to support the compressor off to the side without disconnecting the lines.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the accessory drive belt.
  4.  
  5. Remove the four bolts securing the A/C compressor to the mounting bracket and set aside.
  6.  
  7. Remove the three compressor/power steering bracket retaining bolts.
  8.  
  9. Pull the bracket, with the power steering pump attached, away from the engine and position it aside.
  10.  
  11. Disconnect the engine control sensor wiring from the camshaft position sensor.
  12.  
  13. Remove the two CMP mounting bolts and then pull the sensor from the oil pump.
  14.  

To install:
  1. Install the CMP sensor to the oil pump and tighten the two mounting screws to 45-61 inch lbs. (5-7 Nm).
  2.  
  3. Reconnect the engine control sensor wiring to the sensor.
  4.  
  5. Position the bracket, with the power steering pump attached, to the engine.
  6.  
  7. Install the three compressor/power steering bracket retaining bolts and tighten securely.
  8.  
  9. Install the A/C compressor to the mounting bracket and tighten the four mounting bolts.
  10.  
  11. Install the accessory drive belt.
  12.  
  13. Connect the negative battery cable. Start the engine and check for leaks.
  14.  

1994 B Series Pick-up Equipped With the 3.0L Engine and All 1996-98 MPV Models

Refer to Engine Electrical in this guide for distributor removal and installation.

1995-98 3.0L and 4.0L Engines

See Figures 7, 8, and 9

If the camshaft position sensor housing does not contain a plastic locator cover tool, a special service tool such as T89P-12200-A, or equivalent, must be obtained prior to installation. Failure to follow this procedure may result in improper stator alignment. This will result in the fuel system being out of time with the engine, possibly causing engine damage.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the ignition coil, radio capacitor and ignition coil bracket.
  4.  
  5. Disengage the wiring harness connector from the CMP sensor.
  6.  

Prior to removing the camshaft position sensor, set the No. 1 cylinder to 10° After Top Dead Center (ATDC) of the compression stroke. Note the position of the sensor electrical connection. When installing the sensor, the connection must be in the exact same position.

  1. Position the No. 1 cylinder at 10° ATDC, then matchmark the CMP sensor terminal connector position with the engine assembly.
  2.  
  3. Remove the camshaft position sensor retaining screws and sensor.
  4.  
  5. Remove the retaining bolt and hold-down clamp.
  6.  

The oil pump intermediate shaft should be removed with the camshaft sensor housing.

  1. Remove the CMP sensor housing from the front engine cover.
  2.  



Click image to see an enlarged view

Fig. Fig. 7: Exploded view of the Camshaft Position (CMP) sensor mounting for the 3.0L engine-4.0L engine is similar

To install:
  1. If the plastic locator cover is not attached to the replacement camshaft position sensor, attach a synchro positioning tool, such as Ford Tool T89P-12200-A or equivalent. To do so, perform the following:
    1. Engage the sensor housing vane into the radial slot of the tool.
    2.  
    3. Rotate the tool on the camshaft sensor housing until the tool boss engages the notch in the sensor housing.The cover tool should be square and in contact with the entire top surface of the camshaft position sensor housing.

      Click image to see an enlarged view

      Fig. Fig. 8: Attach the CMP synchro positioning tool to the housing



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      Fig. Fig. 9: CMP sensor positioning for the 3.0L (75) and 4.0L (60) engines

    4.  

  2.  
  3. Transfer the oil pump intermediate shaft from the old camshaft position sensor housing to the replacement sensor housing.
  4.  
  5. Install the camshaft sensor housing so that the drive gear engagement occurs when the arrow on the locator tool is pointed approximately 30° counterclockwise (the sensor terminal connector should be aligned with its matchmarks) from the face of the cylinder block.
  6.  
  7. Install the hold-down clamp and bolt, then tighten the bolt to 15-22 ft. lbs. (20-30 Nm).
  8.  
  9. Remove the synchro positioning tool.
  10.  


CAUTION
If the sensor connector is positioned correctly, DO NOT reposition the connector by rotating the sensor housing. This will result in the fuel system being out of time with the engine. This could possibly cause engine damage. Remove the sensor housing and repeat the installation procedure beginning with step one.

  1. Install the sensor and retaining screws, tighten the screws to 22-31 inch lbs. (2-4 Nm).
  2.  
  3. Attach the engine control sensor wiring connector to the sensor.
  4.  
  5. Install the ignition coil bracket, radio ignition capacitor and ignition coil.
  6.  
  7. Connect the negative battery cable.
  8.  

 
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