Malibu, Malibu MAXX 2006-2008

Throttle Position Sensor

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Operation



The throttle actuator control (TAC) system uses two 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



2.2L (L61) Engine

WARNING
Do not use solvent of any type when cleaning the gasket surfaces on the intake manifold and the throttle body assembly, as damage to the gasket surfaces and throttle body assembly may result. Use care in cleaning the gasket surfaces on the intake manifold and the throttle body assembly, as sharp tools may damage the gasket surfaces.

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the air cleaner resonator.
  4.  
  5. Disconnect the engine wiring harness electrical connector from the Electronic Throttle Control (ETC).
  6.  
  7. Remove the throttle body bolts.
  8.  
  9. Remove the throttle body from the intake manifold.

    Click image to see an enlarged view

    Fig. 2.2L (L61) Throttle body assembly

  10.  

To install:

  1. Inspect the throttle body gasket and replace if necessary.
  2.  
  3. Position the throttle body to the intake manifold.
  4.  
  5. Install the throttle body bolts and tighten to 89 inch. lbs. (10 Nm).
  6.  
  7. Connect the engine wiring harness electrical connector to the ETC.
  8.  
  9. Install the air cleaner resonator.
  10.  

3.5L (LZ4) & 3.9L (LZ9) Engines

WARNING
Do not use solvent of any type when cleaning the gasket surfaces on the intake manifold and the throttle body assembly, as damage to the gasket surfaces and throttle body assembly may result. Use care in cleaning the gasket surfaces on the intake manifold and the throttle body assembly, as sharp tools may damage the gasket surfaces.

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the intake manifold cover.
  4.  
  5. Remove the air cleaner outlet duct.
  6.  
  7. Disconnect the engine wiring harness electrical connector from the Electronic Throttle Control (ETC).
  8.  
  9. Remove the heater inlet and outlet pipe nuts.
  10.  
  11. Remove the heater inlet and outlet pipe bracket from the throttle body studs. Reposition the pipes.

    Click image to see an enlarged view

    Fig. Heater pipes removed

  12.  
  13. Remove the throttle body bolts and nuts.
  14.  
  15. Remove the throttle body.
  16.  
  17. Remove and discard the throttle body gasket.
  18.  

To install:

  1. Install a new throttle body gasket.
  2.  
  3. Install the throttle body.
  4.  
  5. Install the throttle body bolts and nuts.
  6.  
  7. Tighten the nuts and bolts to 89 inch. lbs. (10 Nm).
  8.  
  9. Reposition the heater inlet and outlet pipes and install the pipe bracket to the throttle body studs.
  10.  
  11. Install the heater inlet and outlet pipe nuts and tighten to 89 inch. lbs.
  12.  
  13. Connect the engine wiring harness electrical connector to the ETC.
  14.  
  15. Install the air cleaner outlet duct
  16.  
  17. Install the intake manifold cover.
  18.  
  19. Perform the Throttle Learn Procedure.
  20.  

Testing



Check the Throttle Position (TP) sensor circuits as follows:

  1. Ignition OFF, disconnect the harness connector at the throttle body.
  2.  
  3. Ignition OFF for 90 seconds, test for less than 5 ohms of resistance between the low reference circuit terminal C and ground.
    1. If greater than 5 ohms, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
    2.  

  4.  
  5. Ignition ON, test for 4.8-5.2 volts between 5-volt reference circuit terminal E and ground.
    1. If less than 4.8 volts, test 5-volt reference circuit for a short to ground or an open / high resistance. If the circuit tests normal, replace the ECM.
    2.  
    3. 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.
    4.  

  6.  
  7. Verify the scan tool TP sensor 1 voltage is less than 0.1 volt.
    1. 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.
    2.  

  8.  
  9. Verify the scan tool TP sensor 2 voltage is greater than 4.8 volts.
    1. If less than 4.8 volts, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.
    2.  

  10.  
  11. 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.
    1. If less than 4.8 volts, test the TP sensor 1 signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
    2.  

  12.  
  13. 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
    1. If greater than 1.0 volt, test the TP sensor 2 signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
    2.  

  14.  
  15. Ignition OFF for 90 seconds, disconnect the harness connector at the ECM.
  16.  
  17. Test for less than 5 ohms of resistance on all TP sensor circuits between the following terminals:
    1. ECM C2 signal circuit terminal 65 to TP terminal D
    2.  
    3. ECM C2 signal circuit terminal 63 to TP terminal F
    4.  
    5. ECM C2 5-volt reference circuit terminal 3 to terminal E
    6.  

  18.  
  19. If greater than 5 ohms, repair the affected circuit for open/high resistance.
  20.  
  21. Test for infinite resistance between TP sensor 1 signal circuit terminal D and TP sensor signal circuit terminal F.
    1. If less than infinite resistance, repair the short between TP sensor 1 signal circuit and TP sensor 2 signal circuit.
    2.  

  22.  
  23. If all circuits test normal, replace the throttle body.

    Click image to see an enlarged view

    Fig. Throttle Actuator Control electrical connector

  24.  

Throttle Body Relearn Procedure




NOTE
Do NOT perform this procedure if DTCs are set.

  1. Start and idle the engine in PARK for 3 minutes.
  2.  
  3. With a scan tool, monitor desired and actual RPM.
  4.  
  5. The ECM will start to learn the new idle cells and Desired RPM should start to decrease.
  6.  
  7. Ignition OFF for 60 seconds.
  8.  
  9. Start and idle the engine in PARK for 3 minutes.
  10.  
  11. After the 3 minute run time the engine should be idling normal.
    NOTE
    During the drive cycle the check engine light may come on with idle speed DTCs. If idle speed codes are set, clear codes so the ECM can continue to learn.



    If the engine idle speed has not been learned the vehicle will need to be driven at speeds above 70 km/h (44 mph) with several decelerations and extended idles.
     

  12.  
  13. After the drive cycle, the engine should be idling normally.

    If the engine idle speed has not been learned, turn OFF the ignition for 60 seconds and repeat step 6.
     

  14.  
  15. Once the engine speed has returned to normal, clear DTCs.
  16.  

 
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