LaCrosse 2006-2007

Accelerator Pedal Position Sensor

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Operation



The accelerator pedal contains 2 individual Accelerator Pedal Position (APP) sensors within the assembly. The APP sensors 1 and 2 are potentiometer type sensors each with 3 circuits:



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

The APP sensors are used to determine the pedal angle. The Powertrain Control Module (PCM) provides each APP sensor with a 5-volt reference circuit and a low reference circuit. The APP sensors provide the PCM with signal voltage proportional to the pedal movement. The APP sensor 1 signal voltage at rest position is near the low reference and increases as the pedal is actuated. The APP sensor 2 signal voltage at rest position is near the 5-volt reference and decreases as the pedal is actuated.

Removal & Installation



3.6L Engine
  1. Turn the ignition OFF.
  2.  
  3. Remove the insulator panel from under the dashboard on the driver-s side.
    WARNING
    Handle the electronic throttle control components carefully. Use cleanliness in order to prevent damage. Do not drop or roughly handle the electronic throttle control components. Do not immerse the electronic throttle control components in cleaning solvents of any type.

  4.  
  5. Disconnect the Accelerator Pedal Position (APP) sensor electrical connector from the accelerator pedal module.
  6.  
  7. Remove the APP sensor mounting bolts.
  8.  
  9. Remove the APP sensor from the vehicle.

    Click image to see an enlarged view

    Fig. Accelerator Pedal Position (APP) sensor location-3.6L engine

  10.  

To install:

  1. Position the APP sensor to the mounting plate.
  2.  
  3. Install the APP sensor mounting bolts. Tighten the APP sensor mounting bolts to 89 inch lbs. (10 Nm).
  4.  
  5. Connect the APP sensor electrical connector.
  6.  
  7. Operate the accelerator pedal and observe the APP angles using a scan tool.
    NOTE
    The accelerator pedal should operate freely, without binding between closed throttle and Wide Open Throttle (WOT).

  8.  
  9. Install the insulator panel under the dashboard on the driver-s side.
  10.  

3.8L Engine
  1. Remove the left Instrument Panel (I/P) sound insulator.
  2.  
  3. Disconnect the Accelerator Pedal Position (APP) sensor electrical connector.
  4.  
  5. Remove the accelerated pedal bolts (2).
  6.  
  7. Remove the accelerator pedal (1) from the vehicle.

    Click image to see an enlarged view

    Fig. Accelerator Pedal Position (APP) sensor location-3.8L engine

  8.  

To install:

  1. Position the accelerator pedal (1) to the vehicle.
  2.  
  3. Install the accelerator pedal bolts (2). Tighten the bolts to 44 inch lbs. (5 Nm).
  4.  
  5. Connect APP sensor electrical connector.
  6.  
  7. Install the left I/P sound insulator.
  8.  

Testing



  1. Before beginning vehicle diagnosis, the following preliminary inspections/tests must be performed:

    Ensure that the battery is fully charged
     
    Ensure that the battery cables are clean and tight
     
    Inspect for any open fuses
     
    Ensure that the grounds are clean, tight, and in the correct location
     
    Inspect the easily accessible systems or the visible system components for obvious damage or conditions that could cause the concern. This would include checking to ensure that all connections/connectors are fully seated and secured
     
    Inspect for aftermarket devices that could affect the operation of the system
     
    Search for applicable service bulletins
     

  2.  
  3. Install a scan tool. Verify that the scan tool powers up.
  4.  
  5. With the ignition ON, engine OFF, verify communication with all of the control modules on the vehicle.
  6.  
  7. With the ignition ON, observe the scan tool APP sensor 1 voltage parameter. The readings should be 1.0 volt at rest to just above 4.0 volts when fully depressed. Ensure there is a voltage change with accelerator pedal movement.
  8.  
  9. With the ignition ON, observe the scan tool APP sensor 2 voltage parameter. The readings should be 0.5 volts at rest to more than 2.0 volts with the accelerator pedal fully depressed. Ensure there is a voltage change with accelerator pedal movement.
  10.  
  11. Connect a fused jumper wire between the APP sensor 2 5-volt reference circuit and the APP sensor 2 signal circuit at the accelerator pedal harness connector.
  12.  
  13. Observe the APP sensor 2 voltage parameter with a scan tool. It should read 4.6-5.2 volts.
  14.  
  15. Turn OFF the ignition. Remove the fused jumper.
  16.  
  17. Turn ON the ignition, with the engine OFF.
  18.  
  19. Measure the voltage of the APP sensor 5-volt reference circuit with a DMM. It should read 4.6-5.2 volts.
  20.  
  21. If the reference voltage is below the acceptable range, check the low reference circuit for an open or high resistance interruption.
  22.  
  23. If all circuits are functioning properly and there is no voltage change when the accelerator pedal is moved, replace the APP.

    Click image to see an enlarged view

    Fig. Accelerator Pedal Position (APP) connector end view



    Click image to see an enlarged view

    Fig. Circuit schematics for electronic throttle controls-APP & TAC

  24.  

 
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