Chrysler Neon 1995-1999 Repair Guide

Throttle Position Sensor

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OPERATION



See Figure 1

The Throttle Position Sensor (TPS) is mounted to the side of the throttle body and connects to the throttle blade shaft. The TPS is a variable resistor that provides the PCM with an input signal (voltage). The signal represents throttle blade position. As the position of the throttle blade changes, the resistance of the TPS changes.



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Fig. Fig. 1: Throttle Position Sensor (TPS) location-1995 vehicles

The PCM supplies about 5 volts of DC current to the TPS. The TPS output voltage (input signal to the PCM) represents throttle blade position. For 1995 vehicles, the TPS output voltage to the PCM varies from about 0.5 volt at idle to a maximum of 3.7 volts at wide open throttle. For 1996-99 vehicles, the TPS output voltage to the PCM varies from about 0.6-1.03 volts at idle to a maximum of 3.1-4.0 volts at wide open throttle.

Along with inputs from other sensors, the PCM uses the TPS input to determine current engine operating conditions. The PCM also adjusts fuel injector pulse width and ignition timing based on these inputs.

TESTING



1995 Vehicles

See Figures 2, 3, 4 and 5

The TPS can be tested using a digital ohmmeter. The center terminal of the sensor is the output terminal.

  1. Visually check the connector, making sure it is attached properly and all of the terminals are straight, tight and free of corrosion.
  2.  
  3. Turn the ignition switch to the ON position.
  4.  
  5. Attach a digital ohmmeter and check the output voltage at the center terminal wire of the sensor connector.
  6.  



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Fig. Fig. 2: Check the output voltage at the TPS connector

  1. For a general sensor check.
    1. Turn the ignition key to the ON position with the engine OFF .
    2.  
    3. Attach a digital ohmmeter to the TPS as shown in the accompanying figure.
    4.  
    5. Measure the resistance with the throttle closed, with the throttle about half way open and at wide open throttle.

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      Fig. Fig. 3: Attach a DVOM to the TPS and measure the resistance with the throttle plate closed



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      Fig. Fig. 4: Then, measure the resistance with the throttle plate partially open. Note these values are only a guide line and not absolute



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      Fig. Fig. 5: Finally, measure the resistance at WOT. The resistance should increase smoothly as the throttle is opened

    6.  
    7. The resistance should increase smoothly as the throttle plate is opened,
    8.  

  2.  
  3. Check the output voltage at idle and at Wide Open Throttle (WOT). At idle, the TPS output voltage should be about 0.5 volts. At WOT, the output voltage should about 3.7 volts. The output voltage should gradually increase as the throttle plate moves slowly from idle to WOT.
  4.  
  5. Before replacing the TPS, check for spread terminals and also inspect the PCM connections.
  6.  

1996-99 Vehicles

See Figures 6 and 7

In order to perform a complete test of the TPS and related circuits, you must use a DRB® or equivalent scan tool, and following the manufacturers directions. To check the Throttle Position Sensor (TPS) only, proceed with the following test.

  1. The TPS can be tested using a digital ohmmeter. The center terminal of the sensor is the output terminal. One of the other terminals is a 5 volt supply and the remaining terminal is ground.
  2.  



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Fig. Fig. 6: Throttle Position Sensor (TPS) terminal identification-1996-97 vehicles



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Fig. Fig. 7: Throttle Position Sensor (TPS) terminal identification-1999 vehicles

  1. Connect the DVOM between the center and sensor ground terminals.
  2.  
  3. With the ignition switch in the ON position, check the output voltage at the center terminal wire of the connector. Check the output voltage at idle and at Wide Open Throttle (WOT).
  4.  
  5. For 1996 vehicles, at idle, the TPS output voltage should be about 0.9-1.03 volts. At WOT, the output voltage should be about 3.1-4.0 volts. The output voltage should gradually increase as the throttle plate moves slowly from idle to WOT.
  6.  
  7. For 1997-99 vehicles, at idle, the TPS output voltage should be about 0.9-1.20 volts. At WOT, the output voltage should be about 3.1-4.4 volts. The output voltage should gradually increase as the throttle plate moves slowly from idle to WOT.
  8.  

REMOVAL & INSTALLATION



See Figures 1, 8, 9 and 10

  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the EVAP purge hose from the throttle body.
  4.  
  5. Detach the electrical connector from the IAC motor and the TPS.
  6.  
  7. Remove the throttle body from the vehicle, as outlined in Fuel System of this guide.
  8.  
  9. Unfasten the mounting screws, then remove the TPS from the throttle body.
  10.  



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Fig. Fig. 8: View of the TPS and related components-1999 SOHC engine shown



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Fig. Fig. 9: Location of the TPS and IAC motor on 1996-99 DOHC engines. Note that they share a wiring harness

To install:
  1. The throttle shaft end of the throttle body slides into a socket in the TPS. The socket has 2 tabs inside it. The throttle shaft rests against the tabs. When indexed correctly the TPS can rotate clockwise a few degrees to line up the mounting screw holes with the screw holes in the throttle body. The TPS has slight tension when rotated into position. If it is difficult to rotate the TPS into position, install the sensor with the throttle shaft on the other side of the tabs in the socket.
  2.  



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Fig. Fig. 10: The throttle shaft slides into a socket on the TPS

  1. Install the sensor mounting screws and tighten to 17 inch lbs. (2 Nm).
  2.  
  3. After installing the TPS, the throttle plate should be closed. If the throttle plate is open, install the sensor on the other side of the tabs in the socket.
  4.  
  5. Install the throttle body, as outlined in Fuel System .
  6.  
  7. Attach the electrical connectors to the IAC motor and TPS.
  8.  
  9. Connect the EVAP purge hose to the throttle body nipple.
  10.  
  11. Connect the negative battery cable.
  12.  

 
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