Nissan Sentra/Pulsar/NX 1982-1996 Repair Guide

Idle Speed Control (ISC) Valve

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OPERATION



The ISC valve is used on E16i engine to maintain idle speed during all phases of engine operation. The valve contains rotary solenoid valve which is controlled by the ECM. The ECM uses on/off pulses to control the position of the shutter on the valve. By energizing the valve longer, more air will bypass the throttle plates, thus the engine speed will increase.

TESTING



See Figures 1, 2, 3, 4 and 5



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Fig. Fig. 1: Connect an ohmmeter across the ISC valve terminals, as shown



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Fig. Fig. 2: Apply battery voltage from terminal B to terminal C and the shutter valve should be fully closed-E16i engine



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Fig. Fig. 3: Apply battery voltage from terminal B to terminal A and the shutter valve should be fully opened-E16i engine



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Fig. Fig. 4: With no voltage applied, inspect the shutter valve clearance-E16i engine



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Fig. Fig. 5: ISC valve mounting bolt identification

  1. Turn the ignition switch to the OFF position.
  2.  
  3. Disconnect the ISC valve electrical connector.
  4.  
  5. Connect an ohmmeter between terminals B and C . The reading should be 8.5-9.5 ohms.

    If the reading was within specifications, proceed to the next step.
     
    If the reading was not within specifications, replace the ISC valve assembly.
     

  6.  

  1. Connect an ohmmeter between terminals B and A . The reading should be 9.5-10.5 ohms.

    If the reading was within specifications, proceed to the next step.
     
    If the reading was not within specifications, replace the ISC valve assembly.
     

  2.  

  1. Connect battery positive voltage to terminal B and ground terminal A . With battery voltage applied, observe the shutter valve position. The valve should be fully closed.

    If the shutter valve was fully closed, proceed to the next step.
     
    If the shutter valve was not completely closed, replace the ISC valve assembly.
     

  2.  

  1. Connect battery positive voltage to terminal B and ground terminal C . With battery voltage applied, observe the shutter valve position. The valve should be fully open.

    If the shutter valve was fully opened, proceed to the next step.
     
    If the shutter valve was not completely open, replace the ISC valve assembly.
     

  2.  

  1. Disconnect the battery from the ISC valve. With no voltage applied to the ISC valve, there should be a 0-0.08 in. (0-2mm) opening clearance between the shutter valve and the housing.

    If the measurement was within specifications, proceed to the next step.
     
    If the measurement was not within specifications, replace the ISC valve assembly.
     

  2.  

  1. Visually inspect the rotary shutter for clogging, sticking or binding. Clean shutter or replace if necessary.
  2.  

REMOVAL & INSTALLATION



  1. Disconnect the electrical connector from the ISC valve assembly.
  2.  
  3. Remove the mounting bolts in the reverse order of the tightening sequence.
  4.  
  5. Remove the valve assembly from the side of the throttle body housing.
  6.  

To install:
  1. Position the ISC valve to the side of the throttle body housing.
  2.  
  3. Tighten the mounting bolts in the following sequence: A-B-C to 36 inch lbs. (4.5 Nm).
  4.  
  5. Connect the electrical connector to the ISC valve.
  6.  

 
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