Nissan 240SX/Altima 1993-1998 Repair Guide

Throttle Position Sensor

Print

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

TESTING



See Figures 1, 2, 3 and 4



Click image to see an enlarged view

Fig. Fig. 1: Testing the TP sensor voltage with the throttle closed shows a 0.2 volt reading. This is well within specification



Click image to see an enlarged view

Fig. Fig. 2: This automatic transaxle equipped vehicle uses a wide open throttle switch in the TP sensor. With the throttle wide open, continuity should not exist, as indicated by the 0.L ohms reading



Click image to see an enlarged view

Fig. Fig. 3: Throttle position sensor without idle and wide open throttle switches-manual transaxle/transmission equipped models



Click image to see an enlarged view

Fig. Fig. 4: Throttle position sensor with idle and wide open throttle switches-automatic transaxle/transmission equipped models

Potentiometer
  1. Disconnect the electrical harness from the sensor.
  2.  
  3. Check resistance between the connector terminals.
  4.  
  5. Resistance for 1996-98 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
     

  6.  
  7. Resistance for 1995 model year vehicles should be as follows:

    Throttle closed-approximately 1 kilohm
     
    Throttle partially open-1-10 kilohms
     
    Throttle fully open-approximately 10 kilohms
     

  8.  
  9. Resistance for 1993-94 model year vehicles should be as follows:

    Throttle closed-approximately 2 kilohms
     
    Throttle partially open-2-10 kilohms
     
    Throttle fully open-approximately 10 kilohms
     

  10.  
  11. 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.
  12.  

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
  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 5



Click image to see an enlarged view

Fig. Fig. 5: The throttle position sensor is located on the side of the throttle body

The throttle position sensor is mounted on the throttle body.

  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.  

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 Transmission/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.
  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 transmission/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 Transmission/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 transmission/transaxle in the N position.
  18.  
  19. Reconnect the TP sensor with the engine running.
  20.  

 
label.common.footer.alt.autozoneLogo