Nissan Maxima 1993-1998 Repair Guide

Throttle Position Sensor

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OPERATION



The Throttle Position (TP) sensor is a potentiometer. It is mounted on the side of the throttle body and is connected to the throttle plate shaft. The sensor monitors throttle plate movement and position, and transmits an appropriate electrical signal to the ECM. These signals are used by the ECM to adjust the air/fuel mixture and spark timing according to engine load. The TP sensor is adjustable on some models.

Automatic transaxle TP sensors contain position switches. These switches provide a signal to the ECM when the engine is at idle and wide open throttle.

TESTING



Potentiometer

See Figures 1, 2, 3, 4 and 5



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Fig. Fig. 1: Checking throttle position resistance-1993-94 models



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Fig. Fig. 2: To check for throttle position sensor function, unplug the lower connector and attach the ohmmeter leads to the sensor



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Fig. Fig. 3: With the throttle closed, the resistance should be around 1 kilohm (VE30DE)



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Fig. Fig. 4: As you open the throttle with your hand to the fully open position, resistance should increase



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Fig. Fig. 5: Checking throttle position resistance-1995-98 models

  1. Disconnect the electrical harness from the sensor.
  2.  
  3. Check resistance between the connector terminals.
    1. Resistance for 1993-94 model year vehicles should be as follows:

      Throttle closed-approximately 1 kilohm
       
      Throttle partially open-1-9 kilohms
       
      Throttle fully open-approximately 9 kilohms
       

    2.  

    1. Resistance for 1995-98 model year vehicles should be as follows:

      Throttle closed-approximately 0.5 kilohms
       
      Throttle partially open-0.5-4.0 kilohms
       
      Throttle fully open-approximately 4.0 kilohms
       

    2.  

  4.  

  1. Slowly rotate the throttle shaft and monitor the ohmmeter for a continuous, steady change in resistance. Any sudden jumps, or irregularities in resistance (such as jumping back and forth), indicates a malfunctioning sensor.
  2.  

Do not perform this test on the electrical harness connector terminals, but rather on the terminals of the sensor itself.

  1. If resistance is not within specification, the sensor may be faulty.
  2.  
  3. If resistance is within specification, check the circuits back to the ECM.
  4.  
  5. Connect the electrical harness to the sensor.
  6.  

Position Switches

See Figure 6



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Fig. Fig. 6: Checking the throttle position switch for continuity-1993-94 models

  1. Disconnect the electrical harness from the sensor.
  2.  
  3. Check continuity between the connector terminals.
  4.  
  5. When the throttle is placed in the appropriate position (idle or wide open throttle), continuity should exist.
  6.  
  7. When the throttle is not in the idle or wide open throttle position, continuity should not exist.
  8.  

The position switches are an integral part of the TP sensor and cannot be replaced separately. If faulty, the TP sensor must be replaced as an assembly.

  1. If continuity is not as specified, the sensor is faulty.
  2.  

REMOVAL & INSTALLATION



See Figure 7

  1. Label and disconnect the electrical harness from the sensor.
  2.  
  3. Remove the sensor mounting screws.
  4.  
  5. Remove the sensor from the throttle body.
  6.  



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Fig. Fig. 7: Mark the position of the sensor before removal (throttle body removed for clarity)

To install:
  1. Install the sensor on the throttle body and hand-tighten the screws.
  2.  
  3. Connect the electrical harness to the sensor.
  4.  
  5. Adjust the sensor and tighten the mounting screws securely.
  6.  

ADJUSTMENT



The TP sensor is adjustable on some models. To determine if your model is adjustable, simply look for adjustment slots where the mounting bolts go through the sensor. If slots exist, the sensor is adjustable. If slots do not exist, the sensor is not adjustable.

Inspect the sensor carefully, as large washers may cover the adjustment slots.

Automatic Transaxle Models
  1. Start the engine and allow it to reach operating temperature.
  2.  
  3. Disconnect the TP sensor and closed throttle position switch electrical harness.
  4.  
  5. Check continuity between the closed throttle position switch connector terminals 5 and 6 (1993-94 models check terminals B and C).
  6.  
  7. Raise the engine speed to 2000 rpm, then gradually lower it.
  8.  
  9. Continuity should exist (the closed throttle position switch should close at approximately 1000 rpm with the transaxle in N .
  10.  
  11. If continuity is not as specified, loosen the TP sensor mounting bolts and slowly rotate the sensor.
  12.  
  13. Tighten the mounting bolts securely and recheck continuity.
  14.  

Manual Transaxle Models
  1. Turn the ignition switch ON , but do not start the engine.
  2.  
  3. Backprobe the connector and check voltage between the center terminal and ground.
  4.  
  5. With the throttle closed, voltage should be 0.3-0.7 volts.
  6.  
  7. If voltage is not within specification, loosen the TP sensor mounting bolts and slowly rotate the sensor.
  8.  
  9. Tighten the mounting bolts securely and recheck the voltage.
  10.  
  11. Start the engine and allow it to reach operating temperature.
  12.  
  13. Turn the ignition switch OFF and wait at least 5 seconds.
  14.  
  15. Disconnect the TP sensor electrical harness.
  16.  
  17. Start the engine and wait at least 5 seconds with the transaxle in the N position.
  18.  
  19. Reconnect the TP sensor with the engine running.
  20.  

 
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