Nissan Sentra/Pulsar/NX 1982-1996 Repair Guide

Throttle Position Sensor (TPS) and Throttle Position (TP) Switch Assembly

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OPERATION



See Figure 1



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Fig. Fig. 1: Typical throttle position sensor circuit and operation

All engines use a throttle position sensor to detect changes in the throttle plate angle. An additional switch assembly, to detect idle and full throttle conditions, may also be used. The TPS identifies the position of the throttle plate by transforming the throttle valve position into output voltage and feeding the voltage signal to the control unit. In addition, the TPS detects the opening or closing speed of the throttle valve and feeds the rate of voltage change to the ECM.

Some engines incorporate a throttle switch or switches into the TPS. The TP closed throttle switch closes when the throttle valve is positioned at idle and opens when it is in any other position. The TP wide-open throttle switch closes when the throttle pedal is fully depressed and opens when it is in any other position.

TESTING



Throttle Position Sensor
ALL 1987-90 ENGINES

See Figures 2, 3 and 4



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Fig. Fig. 2: Throttle position sensor test points-GA16i and CA18DE engines



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Fig. Fig. 3: Common throttle position and closed throttle (idle) switch circuit and operation-1987-90 vehicles



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Fig. Fig. 4: Throttle position sensor and ECM terminal identification-E16i engine

  1. Disconnect the TP sensor wire harness connector.
  2.  
  3. Connect a voltmeter between the TP sensor terminal F and a known good engine ground.
  4.  
  5. Turn the ignition switch to the ON position.

    If meter reads 5.0 volts, proceed to the next step.
     
    If meter does not read 5.0 volts, check TP sensor power supply circuitry.
     

  6.  

  1. Reconnect the TP sensor electrical connector.
  2.  
  3. Connect voltmeter between ECM terminal 19 and a known good engine ground.
  4.  
  5. Measure the voltage while opening and closing the throttle. The readings should be approximately 0.4 volts with the throttle at rest and 4.0 volts with the throttle plates fully opened. The sensor voltage should be rise and fall smoothly (linear), with no sharp changes in voltage.
  6.  
  7. If the sensor does not perform as specified, first attempt to adjust the sensor. If unable to adjust, replace the sensor and retest.
  8.  

GA16DE ENGINE

See Figures 5 and 6



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Fig. Fig. 5: Throttle position sensor terminal identification-1991-94 GA16DE engine



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Fig. Fig. 6: Throttle position sensor terminal identification-1995-96GA16DEengine

  1. Disconnect the TP sensor wire harness connector.
  2.  
  3. Connect an ohmmeter between the following TP sensor terminals:

    1991-94 engines-terminals A and B .
     
    1995-96 engines-terminals 2 and 3 .
     

  4.  

  1. Measure the resistance between the TP sensor terminals while opening and closing the throttle plates. The readings should be as follows:

    With the throttle at rest, (idle position), the resistance should be approximately 0.5 kilo-ohms.
     
    With the throttle at wide-open position, (pedal depressed fully), the resistance should be approximately 4.0 kilo-ohms.
     
    With the throttle between idle and full throttle, the resistance should be between 0.5-4.0 kilo-ohms.
     

  2.  
  3. If the sensor does not perform as specified, attempt to adjust the sensor. If unable to adjust, replace the sensor and retest.
  4.  

SR20DE ENGINE

See Figures 7 and 8



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Fig. Fig. 7: Throttle position sensor terminal identification-1991-94 SR20DE engine



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Fig. Fig. 8: Throttle position sensor terminal identification-1995-96 SR20DE engine

  1. Disconnect the TP sensor wire harness connector.
  2.  
  3. Connect an ohmmeter between TP sensor terminals A and B on 1991-94 vehicles, or terminals 2 and 3 for 1995-96 vehicles.
  4.  
  5. Measure the resistance between the TP sensor terminals while opening and closing the throttle plates. The readings should be as follows:

    With the throttle at rest, (idle position), the resistance should be approximately 1 kilo-ohms.
     
    With the throttle at wide-open position, (pedal depressed fully), the resistance should be approximately 10 kilo-ohms.
     
    With the throttle between idle and full throttle, the resistance should be between 1-10 kilo-ohms.
     

  6.  
  7. If the sensor does not perform as specified, attempt to adjust the sensor. If unable to adjust, replace the sensor and retest.
  8.  

Closed Throttle (Idle) Switch
E15ET ENGINE

See Figure 9



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Fig. Fig. 9: Idle switch testing-E15ET engine

  1. Disconnect the idle switch harness connector.
  2.  
  3. Check for continuity between switch terminals 18 and 25 .
  4.  
  5. Continuity should be present with the throttle plate fully closed. When the gas pedal is depressed, continuity should disappear. If switch fails to perform as specified, replace the idle switch.
  6.  

ALL 1987-90 ENGINES

See Figure 10



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Fig. Fig. 10: Idle switch testing-1987-90 engines

All GA16i engines use an idle switch, but these engines do not use a wide-open throttle switch.

  1. Disconnect the idle switch harness connector.
  2.  
  3. Check for continuity between switch terminals A and B .
  4.  
  5. Continuity should be present with the throttle plate fully closed. When the gas pedal is depressed, continuity should disappear. If switch fails to perform as specified, replace the idle switch.
  6.  

SR20DE ENGINE WITH AUTOMATIC TRANSAXLE

See Figures 11 and 12



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Fig. Fig. 11: Closed throttle switch testing-1991-94 SR20DE engine



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Fig. Fig. 12: Closed throttle switch testing-1995-96 SR20DE engine

  1. Disconnect the closed TP switch harness connector.
  2.  
  3. Check for continuity between the switch terminals:

    1991-94 vehicles-1 and 2
     
    1995-96 vehicles-2 and 3
     

  4.  
  5. Continuity should be present with the throttle plate fully closed. When the gas pedal is depressed, continuity should disappear. If switch fails to perform as specified, replace the switch.
  6.  

Wide-Open Throttle Switch
SR20DE ENGINE WITH AUTOMATIC TRANSAXLE

See Figures 13 and 14



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Fig. Fig. 13: Wide-open switch testing-1991-94 SR20DE engine



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Fig. Fig. 14: Wide-open switch testing-1995-96 SR20DE engine

  1. Disconnect the closed TP switch harness connector.
  2.  
  3. Check for continuity between the switch terminals:

    1991-94 vehicles-2 and 3
     
    1995-96 vehicles-1 and 2
     

  4.  
  5. No continuity should be present with the throttle plate closed. When the gas pedal is fully depressed, continuity should exist. If switch fails to perform as specified, replace the switch.
  6.  

REMOVAL & INSTALLATION



  1. Disconnect the wiring connector at the Throttle Position Sensor (TP).
  2.  
  3. Remove the two mounting screws and the sensor.
  4.  

To install:
  1. Install the sensor on the throttle body but leave the mounting screws loose enough to rotate the sensor.
  2.  
  3. Connect the wiring connector.
  4.  
  5. Adjust the sensor and tighten the screws.
  6.  

ADJUSTMENT



Except GA16DE and SR20DE Engines
  1. Start the engine and allow it to reach normal operating temperature.
  2.  
  3. Disconnect the throttle valve switch harness connector and throttle sensor harness connector.
  4.  
  5. Check the idle speed and if necessary, adjust to specification following proper procedures.
  6.  
  7. Manually open the throttle valve until the engine speed reaches 2000 rpm. Lower the engine speed slowly and note the rpm at which the idle contact turns from OFF to ON. It should be approximately 300 plus or minus 150 rpm over whatever engine speed was recorded in the previous step. If not as specified, adjust by loosening the throttle valve switch securing screws and turning the throttle valve switch.
  8.  
  9. Reconnect the throttle valve switch harness connector and throttle sensor harness connector.
  10.  

GA16DE and SR20DE Engines
  1. Install the TP sensor body in the throttle body. If the retaining bolts are tightened, loosen them enough for the sensor to move.
  2.  
  3. Rotate the TP sensor body until the output voltage is 0.45-0.55 volts on 1991-94 engines or 0.35-0.65 volts on 1995-96 engines.
  4.  
  5. Tighten the mounting bolts.
  6.  
  7. Disconnect the TP sensor harness briefly, then reconnect the harness.
  8.  

 
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