Ram B1500, B2500, B3500, 1999-2003

Throttle Position Sensor

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Operation



The Throttle Position (TP) sensor is a potentiometer that provides a signal to the ECM that is directly proportional to the throttle plate position. The TP sensor is mounted on the side of the throttle body and is connected to the throttle plate shaft. The TP 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, spark timing and EGR operation according to engine load at idle, part throttle, or full throttle. The TP sensor is not adjustable.

The Throttle Position (TP) sensor is a potentiometer that provides a signal to the ECM that is directly proportional to the throttle plate position. The TP sensor is mounted on the side of the throttle body and is connected to the throttle plate shaft. The TP 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, spark timing and EGR operation according to engine load at idle, part throttle, or full throttle. The TP sensor is not adjustable.

The Throttle Position sensor (TPS) is a potentiometer that provides a voltage signal to the PCM that is directly proportional to the throttle plate position. The sensor is mounted on the side of the throttle body and is connected to the throttle plate shaft. The TPS monitors throttle plate movement and position, and transmits an appropriate electrical signal to the PCM. These signals are used by the PCM to adjust the air/fuel mixture, spark timing and EGR operation according to engine load at idle, part throttle, or full throttle. The TPS is not adjustable.

The TPS receives a 5-volt reference signal and a ground circuit from the PCM. A return signal circuit is connected to a wiper that runs on a resistor internally on the sensor. The further the throttle is opened, the wiper moves along the resistor, at wide open throttle, the wiper essentially creates a loop between the reference signal and the signal return returning the full or nearly full 5 volt signal back to the PCM. At idle the signal return should be approximately 0.9 volts.



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Fig. TPS location on the throttle body-typical

Removal & Installation



  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner assembly.
  4.  
  5. Unplug the TPS connector.
  6.  
  7. Remove the two retaining bolts.
  8.  
  9. Remove the sensor from the throttle body.
  10.  

To install:

  1. Install the sensor on the throttle body.
  2.  
  3. Tighten the sensor bolts to 60 inch lbs. (7 Nm)
  4.  
  5. Open the throttle to WOT and back again several times to check for binding.
  6.  
  7. Plug in the connector.
  8.  
  9. Install the air cleaner assembly.
  10.  
  11. Connect the negative battery cable.
  12.  



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Fig. TPS mounting-typical



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Fig. Align the locating tangs on the TPS with the throttle shaft

Testing



  1. Remove the engine cover.
  2.  
  3. Remove the air cleaner assembly.
  4.  
  5. With the engine OFF and the ignition ON, check the voltage at the center terminal of the TP sensor by carefully backprobing the connector.
  6.  
  7. Voltage should be between 0.2 and 1.4 volts at idle, and less than 4.8v at Wide Open Throttle (WOT). If the TP sensor does not meet these specifications, replace it.
  8.  
  9. If no voltage is present, check the wiring harness for supply voltage (5.0v) and ground (0.3v or less), by referring to your corresponding wiring guide. If supply voltage and ground are present, but no output voltage from TP, replace the TP sensor. If supply voltage and ground do not meet specifications, make necessary repairs to the harness or ECM.
  10.  
  11. Replace the air cleaner assembly.
  12.  
  13. Replace the engine cover.

    Click image to see an enlarged view

    Fig.



    Click image to see an enlarged view

    Fig.



    Click image to see an enlarged view

    Fig.



    Click image to see an enlarged view

    Fig.

  14.  

  1. Remove the engine cover.
  2.  
  3. Remove the air cleaner assembly.
  4.  
  5. With the engine OFF and the ignition ON, check the voltage at the center terminal of the TP sensor by carefully backprobing the connector.
  6.  
  7. Voltage should be between 0.2 and 1.4 volts at idle, and less than 4.8v at Wide Open Throttle (WOT). If the TP sensor does not meet these specifications, replace it.
  8.  
  9. If no voltage is present, check the wiring harness for supply voltage (5.0v) and ground (0.3v or less), by referring to your corresponding wiring guide. If supply voltage and ground are present, but no output voltage from TP, replace the TP sensor. If supply voltage and ground do not meet specifications, make necessary repairs to the harness or ECM.
  10.  
  11. Replace the air cleaner assembly.
  12.  
  13. Replace the engine cover.

    Click image to see an enlarged view

    Fig.



    Click image to see an enlarged view

    Fig.



    Click image to see an enlarged view

    Fig.



    Click image to see an enlarged view

    Fig.

  14.  

  1. With the engine OFF and the ignition ON , check the voltage at the signal return circuit of the TP sensor by carefully backprobing the connector using a DVOM.
  2.  
  3. Voltage should be between 0.2 and 1.4 volts at idle.
  4.  
  5. Slowly move the throttle pulley to the wide open throttle (WOT) position and watch the voltage on the DVOM. The voltage should slowly rise to slightly less than 4.5v at Wide Open Throttle (WOT).
  6.  
  7. If no voltage is present, check the wiring harness for supply voltage (5.0v) and ground (0.3v or less), by referring to your corresponding wiring guide. If supply voltage and ground are present, but no output voltage from TPS, replace the TPS. If supply voltage and ground Do NOT meet specifications, make necessary repairs to the harness or PCM.
  8.  



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Fig. Identifying Throttle Position Sensor electrical connector terminals



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Fig. Throttle Position Sensor circuit schematic



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Fig. Using a voltmeter to check the TPS for signal voltage



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Fig. Using a voltmeter to check the TPS for reference (supply) voltage



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Fig. You can use the data display function of the Auto Xray®, or other scan tool, to get the TPS readings

 
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