Mitsubishi Pick-ups and Montero 1983-1995 Repair Guide

Camshaft Position Sensor

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OPERATION



See Figures 1 through 6

The Camshaft Position Sensor (CPS) is located integral to the distributor on 2.4L and 3.0L (12 valve) engines, and is located on the front-upper timing belt cover of 3.0L (24 valve) and 3.5L engines. The CPS detects the top dead center position of the No. 1 cylinder. It sends a signal to the ECM when this position is detected. The ECM uses this information to help it decide how to run the fuel injection sequence, among other functions. The power for the CPS is supplied from the MFI relay and is grounded to the vehicle body. The CPS, by intermitting the flow (to ground) of the 5 volts applied from the ECM, produces the pulse signals.

If there is a malfunction of the CPS, the sequential multiport fuel injection will not be correct. This will result in such problems as engine stalling, unstable idling, and poor acceleration.



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Fig. Fig. 1: The CPS, along with the crankshaft position sensor, is located inside of the distributor-2.4L engines



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Fig. Fig. 2: The CPS and CSPS harness connector is mounted on the firewall on Pick-up trucks equipped with the 2.4L engine



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Fig. Fig. 3: On 3.0L (12 valve) engines, the CPS and CSPS are located inside of the distributor



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Fig. Fig. 4: The CPS location under the upper left-hand timing belt cover-3.0L (24 valve) and 3.5L engines



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Fig. Fig. 5: The location of the CPS harness connector-3.0L (24 valve) engines



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Fig. Fig. 6: The location of the CPS harness connector-3.5L engines

HARNESS TESTING



2.4L Engines

See Figure 7

The 1993-95, rear-wheel drive 2.4L (California) Pick-ups have the same engine controls as the 3.0L engines. All other 2.4L engines are listed as 2.4L engines.

  1. Disconnect the CPS harness connector and turn the ignition ON . Measure the power supply voltage of CPS harness terminal 3 (to ground). The voltage should be the battery voltage (i.e. 10-12 volts). If this is not the case, repair or replace the harness between CPS terminal 3 and the ignition switch.
  2.  
  3. Turn the ignition switch OFF and check for continuity of the ground circuit, which is CPS harness terminal 2. If no continuity is found, repair or replace the harness from CPS terminal 2 to ground.
  4.  
  5. Turn the ignition switch back ON and check the voltage of the CPS harness terminal 4 (output circuit). The voltage should be between 4.8-5.2 volts, if it is not, repair the harness from CPS terminal 4 to ECM terminal 22.
  6.  
  7. If the harness passed all of the tests, it is good.
  8.  
  9. Plug all connectors back into their original components.
  10.  



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Fig. Fig. 7: The numbering of the terminals on the component (sensor) side of the CPS connector-2.4L engines

3.0L (12 Valve) Engines

See Figure 8

  1. Unplug the MFI relay harness connector and the distributor harness connector. While touching the ohmmeter probes to both ends of the harness, check for continuity between the CPS (distributor) harness terminal 3 and the MFI relay harness terminal 5. If no continuity is found, repair the harness between these two terminals.
  2.  
  3. Plug the MFI relay harness back in, and check for continuity in the ground circuit, that is terminal 4 of the CPS (distributor) harness to ground. If no continuity exists, repair the harness between CPS harness terminal 4 and the ground.
  4.  
  5. Unplug the ECM harness connector. Check for an open or short-circuit between the CPS harness terminal 1 and ECM harness terminal 22, and CPS harness terminal 2 and ECM harness terminal 21. If a short or open-circuit is found, repair the harness between the two terminals.
  6.  
  7. Turn the ignition switch ON . Check the output circuit voltage. This is CPS harness terminal 1 to ground. If the output voltage is not 4.8-5.2V, replace the ECM with a new unit.
  8.  
  9. Plug all connectors back into their original components.
  10.  



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Fig. Fig. 8: The numbering of the terminals on the component (sensor) side of the CPS connector-3.0L (12 valve) engines

3.0L (24 Valve) and 3.5L Engines

See Figure 9

  1. Unplug the MFI relay harness connector and the CPS harness connector. Insert the probes of the circuit tester into both ends of the harness. Check for continuity between the CPS harness terminal 3 and MFI relay terminal 3. If there is no continuity, repair the harness between these two terminals.
  2.  
  3. Plug the MFI relay connector back in. Check for continuity in the ground circuit, which is CPS terminal 1 to ground. If no continuity in the circuit, repair the harness between CPS harness terminal 1 to ground.
  4.  
  5. Unplug the ECM harness connector. Check the CPS harness terminal 2 and ECM terminal 68 for an open or short-circuit to ground. If there is a short or open-circuit, repair the harness between the two terminals.
  6.  
  7. Turn the ignition switch ON . Measure the applied voltage of CPS harness terminal 2 to ground. The voltage should be between 4.8-5.2 volts, if it is not, replace the ECM with a new unit. If the harness passed all of the tests, the harness is good.
  8.  
  9. Plug all connectors back into their original components.
  10.  



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Fig. Fig. 9: The numbering of the terminals on the component (sensor) side of the CPS connector-3.0L (24 valve) and 3.5L Engines

COMPONENT TESTING



Mitsubishi does not give testing procedures of the CPS itself with an ohmmeter. To test this component an oscilloscope is needed. Due to the high cost, and special skills needed to operate the tool, have the component diagnosed by a dealer or reputable service facility after you check the harness for any possible malfunctions. Take the vehicle to an automotive mechanic familiar with Mitsubishi vehicles to have the sensor properly checked out.

REMOVAL & INSTALLATION



On the 2.4L and 3.0L (12 valve) engines, the CPS is located inside the distributor. If the CPS is found to be faulty the entire distributor must be removed and either rebuilt or replaced. Refer to Engine & Engine Rebuilding for distributor removal and installation procedures.

On the 3.0L (24 valve) and 3.5L engines, the CPS is located under the front-upper timing belt cover. The sensor can be removed and replaced with a new one, however refer to Engine & Engine Rebuilding for the timing belt removal and installation procedures for preliminary accessory removal. Only remove the upper left-hand timing belt cover, though, and do not remove the timing belts, other timing belt covers or anything else that is not directly in the way. Unbolt the two mounting bolts and remove the sensor from the front of the engine head.

To install the new sensor, secure it in place with the bolts removed from the old sensor. Reinstall all of the components removed for access.

 
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