CTS 2006-2007, CTS-V 2005-2007, DTS 2006-2007

Throttle Position Sensor

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Operation



The Throttle Actuator Control (TAC) system uses 2 Throttle Position (TP) sensors to monitor the throttle position. The TP sensors 1 and 2 are located within the throttle body assembly. Each sensor has the following circuits:



A 5-volt reference circuit
 
A low reference circuit
 
A signal circuit
 

Two processors are also used to monitor the TAC system data. Both processors are located within the Engine Control Module (ECM). Each signal circuit provides both processors with a signal voltage proportional to throttle plate movement. Both processors monitor each other's data to verify that the indicated TP calculation is correct.

Removal & Installation



2.8L & 3.6L Engines
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Turn the ignition OFF .
  4.  
  5. Remove the air cleaner intake duct.
  6.  
  7. Remove the throttle body electrical connector.
  8.  
  9. Unlock and reposition the wiring harness conduit.
  10.  
  11. Remove the throttle body bolts.
  12.  
  13. Remove the throttle body and gasket.
  14.  

To install:

  1. Carefully clean the throttle body mounting surfaces of any gasket and/or seal material.
  2.  
  3. Install the throttle body and NEW gasket.
  4.  
  5. Install the throttle body bolts and tighten to 89 inch lbs. (10 Nm).
  6.  
  7. Install the wiring harness conduit.
  8.  
  9. Install the throttle body electrical connector.
  10.  
  11. Install the air cleaner intake duct.
  12.  
  13. Perform the idle learn procedure as follows:
    1. Ensure that the following conditions are met: The vehicle is stopped, the accelerator pedal angle is less than 14.9 percent, the battery voltage is more than 10 volts, the Engine Coolant Temperature (ECT) is between 5-60°C (41-140°F) and the Intake Air Temperature (IAT) is more than 5-60°C (41-140°F).
    2.  
    3. Turn OFF the ignition for 30 seconds.
    4.  
    5. Turn ON the ignition, with the engine OFF for 1 minute.
    6.  
    7. Turn OFF the ignition.
    8.  
    9. Clear DTCs as necessary.
    10.  

  14.  

4.6L Engine
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the fuel injector sight shield.
  4.  
  5. Remove the air cleaner outlet duct.
  6.  
  7. Disconnect the Positive Crankcase Ventilation (PCV) fresh air tube quick connect fittings at the camshaft cover and the air cleaner outlet duct.
  8.  
  9. Remove the PCV fresh air tube.
  10.  
  11. Disconnect the engine harness electrical connector from the throttle actuator.
  12.  
  13. Remove the transaxle vent hose clip from the shift cable bracket.
  14.  
  15. Remove the transaxle shift cable clip from the shift cable bracket.
  16.  
  17. Remove the throttle body bolts.
  18.  
  19. Remove the shift cable bracket.
  20.  
  21. Remove the throttle body.
  22.  
  23. Remove and discard the throttle body seal.

    Click image to see an enlarged view

    Fig. View of 4.6L throttle body removal

  24.  

To install:

  1. Install a new throttle body seal.
  2.  
  3. Position the throttle body.
  4.  
  5. Position the shift cable bracket.
  6.  
  7. Install the throttle body bolts and tighten to 89 inch. lbs. (10 Nm).
  8.  
  9. Install the transaxle shift cable clip to the shift cable bracket.
  10.  
  11. Install the transaxle vent hose clip to the shift cable bracket.
  12.  
  13. Connect the engine harness electrical connector to the throttle actuator.
    NOTE
    Route the PCV fresh air tube under the vacuum brake booster hose and the Evaporative Emission (EVAP) purge valve.

  14.  
  15. Install the PCV fresh air tube.
  16.  
  17. Connect the PCV fresh air tube quick connect fittings at the camshaft cover and the air cleaner outlet duct.
  18.  
  19. Install the air cleaner outlet duct.
  20.  
  21. Install the fuel injector sight shield.
  22.  

5.7L Engine
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the fuel injector sight shield.
  4.  
  5. Raise and support the vehicle.
  6.  
  7. Partially drain the cooling system in order to allow the hoses at the throttle body to be removed.
  8.  
  9. Lower the vehicle.
  10.  
  11. Loosen the air cleaner outlet duct clamps.
  12.  
  13. Remove the air cleaner outlet duct.
  14.  
  15. Disconnect the air control valve electrical connector.
  16.  
  17. Disconnect the Throttle Position (TP) sensor electrical connector.
  18.  
  19. Disconnect the crankcase ventilation hose from the throttle body.
  20.  
  21. Disconnect the coolant hoses from the throttle body.
  22.  
  23. Remove the throttle body attaching bolts.
  24.  
  25. Remove the throttle body and the gasket.
  26.  
  27. Discard the throttle body gasket.
  28.  
  29. Inspect the crankcase ventilation hose and the tube. Replace any damaged components.
  30.  

To install:

  1. Install a new throttle body gasket.
  2.  
  3. Connect the coolant hoses to the throttle body.
  4.  
  5. Install the throttle body assembly.
  6.  
  7. Install the throttle body attaching bolts and tighten to 106 inch lbs. (12 Nm).
  8.  
  9. Connect the TP sensor electrical connector.
  10.  
  11. Connect the crankcase ventilation hose to the throttle body.
  12.  
  13. Connect the air control valve electrical connector.
  14.  
  15. Install the air cleaner outlet duct and clamps.
  16.  
  17. Connect the intake air temperature sensor electrical connector.
  18.  
  19. Refill the cooling system.
  20.  
  21. Check for complete throttle opening and closing positions by operating the accelerator pedal. Monitor the throttle angles, using a scan tool. The accelerator pedal should operate freely without binding between full closed throttle and wide open throttle.
  22.  
  23. Start the engine.
  24.  
  25. Check for coolant leaks.
  26.  
  27. Install the fuel injector sight shield.
  28.  

6.0L Engine
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the engine sight shield.
  4.  
  5. Remove the air cleaner outlet duct.
  6.  
  7. Disconnect the throttle body electrical connector.
  8.  
  9. Remove the throttle body attaching bolts.
  10.  
  11. Remove the throttle body and the gasket.
    NOTE
    Do not reuse the throttle body gasket. Install a new gasket during assembly.

  12.  
  13. Discard the throttle body gasket.

    Click image to see an enlarged view

    Fig. Throttle body (508) gasket (509) and mounting bolt (538)

  14.  

To install:

  1. Install a new throttle body gasket.
  2.  
  3. Install the throttle body assembly.
  4.  
  5. Install the throttle body attaching bolts and tighten to 106 inch lbs. (12 Nm).
  6.  
  7. Connect the throttle body electrical connector.
  8.  
  9. Install the air cleaner outlet duct.
  10.  
  11. Check for complete throttle opening and closing positions by operating the accelerator pedal. Monitor the throttle angles, using a scan tool. The accelerator pedal should operate freely without binding between full closed throttle and wide open throttle.
  12.  
  13. Install the engine sight shield.
  14.  

Testing



2.8L & 3.6L Engines
  1. Turn OFF the ignition.
  2.  
  3. Disconnect the throttle body harness connector.
  4.  
  5. Turn ON the ignition, with the engine OFF.
  6.  
  7. Set up a DMM to test amperage on the 400 mA scale.
  8.  
  9. Measure the amperage from the 5-volt reference circuit of the Throttle Position (TP) sensor to the Engine Control Module (ECM) housing. Reading should be 50 mA.
  10.  
  11. If the amperage is more than the specified value, test for an intermittent and for a poor connection at the throttle body assembly.
  12.  
  13. If the reading was as specified. Test the 5-volt reference circuit of the TP sensor and all shared 5-volt reference circuits for one of the following conditions:
    NOTE
    The 5-volt reference circuits are internally connected within the controller. Other sensors that share the 5-volt reference circuit may also have DTCs set. Disconnecting a sensor on the shared 5-volt reference circuit may isolate a shorted sensor. Review the electrical schematic and diagnose the shared circuits and sensors



    An open
     
    A short to ground
     
    A high resistance
     



    Click image to see an enlarged view

    Fig. Throttle body assembly harness connector 2.8L & 3.6L

  14.  

4.6L & 6.0L Engines
  1. Ignition OFF, disconnect the harness connector at the throttle body. Allow sufficient time for the ECM to completely power down.
  2.  
  3. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit terminal C and ground.
  4.  
  5. If greater than 5 ohms, test the low reference circuit for an open/high resistance. . If the circuit tests normal, replace the ECM.
  6.  
  7. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminals E and ground.
  8.  
  9. If less than 4.8 volts, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
  10.  
  11. If greater than 5.2 volts, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  12.  
  13. Verify the scan tool TP sensor 1 voltage is less than 0.1 volt.
  14.  
  15. If greater than 0.1 volt, test the signal circuit terminal D for a short to voltage. If the circuit tests normal, replace the ECM.
  16.  
  17. Verify the scan tool TP sensor 2 voltage is greater than 4.8 volts.
  18.  
  19. If less than 4.8 volts, test the signal circuit terminal F for a short to ground. If the circuit tests normal, replace the ECM
  20.  
  21. Install a 3A fused jumper wire between the signal circuit terminal D and the 5-volt reference circuit terminal E of the TP sensor 1, verify the TP sensor 1 voltage is greater than 4.8 volts.
  22.  
  23. If less than 4.8 volts, test the TP sensor 1 signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
  24.  
  25. Ignition ON, verify that a test lamp does not illuminate between the TP sensor 2 signal circuit terminal F and ground.
  26.  
  27. If the test lamp illuminates, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  28.  
  29. Install a 3A fused jumper wire between the signal circuit terminal F and the low reference circuit terminal C of the TP sensor 2. Verify that the TP sensor 2 voltage is less than 0.1 volt.
  30.  
  31. If greater than 0.1 volt, test TP sensor 2 signal circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  32.  
  33. Ignition OFF, disconnect the harness connector at the ECM.
  34.  
  35. Test for less than 5 ohms of resistance on all TP sensor circuits between the following terminals:

    The ECM C2 signal circuit terminal 64 to TP terminal D
     
    The ECM C2 signal circuit terminal 66 to TP terminal F
     
    The ECM C2 5-volt reference circuit terminal 44 to TP terminal E
     

  36.  
  37. If greater than 5 ohms, repair the affected circuit for an open/high resistance.
  38.  
  39. Test for infinite resistance between TP sensor 1 signal circuit terminal D and TP sensor 2 signal circuit terminal F.
  40.  
  41. If less than infinite resistance, repair the short between TP sensor 1 signal circuit and TP sensor 2 signal circuits.
  42.  
  43. If all circuits test normal, replace the throttle body.

    Click image to see an enlarged view

    Fig. Throttle body assembly harness connector 4.6L & 6.0L

  44.  

5.7L Engine
  1. Inspect the TAC module connectors for signs of water intrusion. When water intrusion occurs, multiple DTCs could be set with no DTC circuit or component conditions found during diagnostic testing.
  2.  
  3. When the TAC module detects a condition within the TAC system, more than one TAC system related DTC may set. This is due to the many redundant tests that run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting the components during testing may set additional DTCs. Keep this in mind when reviewing the Capture info
  4.  
  5. Test all control module voltage supply circuits. Many vehicles have multiple circuits supplying voltage to a control module. Other components in the system may have separate voltage supply circuits that may also need to be tested. Inspect connections at the module/component connectors, fuses, and any intermediate connections between the voltage source and the module/component. A test lamp or a DMM may indicate that voltage is present, but neither tests the ability of the circuit to carry sufficient current. Ensure that the circuit can carry the current necessary to operate the component.
  6.  

 
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