Mazda Trucks 1987-1993 Repair Guide

Camshaft Position (CMP) Sensor

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OPERATION



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

TESTING



Navajo
THREE WIRE SENSORS

See Figure 1

  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.  



Click image to see an enlarged view

Fig. Fig. 1: CMP sensor wire harness connections for the 3-wire sensor

TWO WIRE SENSORS

See Figure 2

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

Pick-up and MPV Models

See Figures 3 and 4

  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.  



Click image to see an enlarged view

Fig. Fig. 3: Rotate the distributor drive and check the output signal



Click image to see an enlarged view

Fig. Fig. 4: 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



Pick-up and MPV Models

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

Navajo

See Figures 5 and 6

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.  

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. 5: Attach the CMP synchro positioning tool to the housing



      Click image to see an enlarged view

      Fig. Fig. 6: CMP sensor positioning

    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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