Sienna 1998-1999

Throttle Position Sensor

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Operation



Specific to:

Toyota Sienna 1998-2005

The Throttle Position Sensor (TPS) is a Linear Potentiometer that monitors the throttle position. The TPS operates within a 5 volt DC reference range, and provides a linear input signal to the Powertrain Control Module (PCM). The PCM uses data from the TPS to calculate Air-Fuel mixture, ignition timing, fuel injector pulse width, and transmission/transaxle gear position.

Removal & Installation



Specific to:

Toyota Sienna 1998-2003

  1. Before servicing the vehicle, refer to the precautions.
  2.  
  3. Drain engine coolant .
  4.  
  5. Remove V-bank cover.
    1. Using a 5 mm hexagon wrench, remove the 3 cap nuts.
    2.  
    3. Loosen the V-bank cover fastener counterclockwise.
    4.  
    5. Remove the V-bank cover.
    6.  

  6.  
  7. Remove air cleaner hose with resonator.
    1. Disconnect the PCV hose.
    2.  
    3. Disconnect the vacuum hose (from the VSV for the active engine control mount).
    4.  
    5. Loosen the 3 hose clamps, and remove the air cleaner hose with the resonator.
    6.  

  8.  
  9. Disconnect accelerator cable and throttle cable.
  10.  
  11. Remove throttle body.
    1. Remove the bolt holding the throttle body to the throttle body bracket.
    2.  
    3. Disconnect the throttle position sensor connector.
    4.  
    5. Disconnect the IAC valve connector.
    6.  
    7. Disconnect the wire clamp.
    8.  
    9. Disconnect the water bypass hose (from the intake manifold).
    10.  
    11. Disconnect the water bypass hose (from the water inlet housing).
    12.  
    13. Disconnect the air assist hose.
    14.  
    15. Disconnect the fuel vapor feed hose (from the emission control valve set).
    16.  
    17. Disconnect the vacuum hose (from the No. 1 ACIS VSV).
    18.  
    19. Disconnect the vacuum hose (from the vacuum tank for the ACIS).
    20.  
    21. Remove the 3 nuts, throttle body and gasket.

      Click image to see an enlarged view

      Fig. Removing the throttle body

    22.  

  12.  

To install:

  1. Installation is the reverse of removal.
  2.  
  3. Install a new gasket on the air intake chamber.
  4.  
  5. Tighten bolts/nuts to specification as follows:

    Throttle body bracket: 14 ft. lbs. (20 Nm)
     
    Throttle body: 22 ft. lbs. (29 Nm)
     

  6.  

Testing



Specific to:

Toyota Sienna 1998-2005


NOTE
Refer to the Electrical Wiring Diagram for component and connector locations, connector views, and circuit-specific information.

Connection & Wiring Diagnosis

Specific to:

Toyota Sienna 1998-2005

Refer to the Electrical Wiring Diagram for component and connector locations, connector views, and circuit-specific information.

Many intermittent open or short circuits may be caused by wiring harness and connector movement due to vibration, engine torque, bumps and rough pavement, etc.

  1. Test the wiring harness and connectors by performing the following tests:

    Move the related connectors and wiring while monitoring the appropriate scan tool data.
     
    Move the related connectors and wiring with the component commanded ON and OFF. Using a suitable the scan tool, observe the component operation.
     
    With the engine running, move the related connectors and wiring while monitoring component operation.
     
    If harness or connector movement affects the data displayed, the component and system operation, or the engine operation, inspect and repair the harness or connections as necessary.
     

  2.  
  3. Test the connector terminal pins and/or wiring by performing the following tests:

    Inspect for incorrect mating of the connector halves, or terminals not fully seated in the connector body.
     
    Inspect for improperly formed or damaged terminals and test for incorrect terminal tension.
     
    Inspect for poor terminal to wire connections including terminals crimped over insulation. This requires removing the terminal from the connector body.
     
    Inspect for corrosion or water intrusion. Pierced or damaged insulation can allow moisture to enter the wiring. The conductor can corrode inside the insulation with little visible evidence. Look for swollen and/or brittle sections of wire in the suspect circuits.
     
    Inspect for wires that are broken inside the insulation by gently pulling on suspect sections of wiring.
     

  4.  

Related Diagnostic Trouble Codes

Specific to:

Toyota Sienna 1998-2005



Click image to see an enlarged view

Fig. Related Diagnostic Trouble Codes

Throttle Position Sensor

Specific to:

Toyota Sienna 1998-2005

A properly operating TPS should display a linear -sweep- of the entire throttle range, and should not exhibit any voltage drop or signal break. If the feedback signal is not within the specified range, additional diagnosis is required in order to determine the proper function of the TPS, or if a fault exists in any related sub-systems.

Click image to see an enlarged view

Fig. Throttle Position Sensor Range Chart

Throttle Position Sensor Strategy

Specific to:

Toyota Sienna 1998-2005

The TPS provides a linear input signal to the Powertrain Control Module (PCM), which is used to monitor the throttle position. The TPS monitors the entire range of throttle opening from 0.5 volts DC (0%) 4.5 volts DC (100%). In modern drive-by-wire throttle control systems, the TPS provides data to the PCM in order to calculate the desired throttle position, in addition to Air-Fuel mixture, ignition timing, fuel injector pulse width, and transmission/transaxle gear position.

The TPS utilizes positive coefficient logic: as the accelerator position is increased, the voltage is increased.

 
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