As you're probably already aware, the accelerator pedal on your 3.5L V6 equipped Chevrolet Malibu or Pontiac G6 comes equipped with an accelerator pedal position sensor assembly.
This tutorial will explain the basic operating theory of the accelerator pedal position (APP) sensors that make up the APP sensor assembly.
NOTE: This tutorial applies to the 2007, 2008, 2009 3.5L V6 (N) Chevrolet Malibu and 2007, 2008, 2009, and 2010 3.5L V6 (N) Pontiac G6.
Contents of this tutorial at a glance:
You can find this tutorial in Spanish here: Cómo Funciona El Sensor APP 1 y 2 (2007-2009 3.5L Chevrolet Malibu y Pontiac G6) (at: autotecnico-online.com).
NOTE: The following tutorials complement this tutorial:
- TAC Circuit Wiring Diagram (2007-2009 3.5L Chevy Malibu And Pontiac G6).
- Electronic Throttle Body Tests (2007-2009 3.5L Chevrolet Malibu And Pontiac G6).
How Does The APP Sensor Work?
In the older GM non-TAC system equipped vehicles, the accelerator pedal was connected to the throttle plate thru' a mechanical accelerator cable. So when you stepped on or off the accelerator pedal; this mechanical cable would open or close the throttle plate in the throttle body.
In your throttle actuator control (TAC) system equipped vehicle, the accelerator pedal is no longer physically connected to the throttle plate by a mechanical accelerator cable.
What now opens and closes the throttle plate, as you step on or off the accelerator pedal is a combination of the following components:
- Accelerator pedal position (APP) sensors.
- Fuel injection computer (also known as the powertrain control module -PCM).
- Throttle actuator motor.
- TP sensor 1 and TP sensor 2.
So, as you step on the accelerator pedal, the APP sensors attached to it inform the fuel injection computer how much the pedal has traveled. The fuel injection computer now activates the throttle actuator motor to open the throttle plate. This of course lets more air into the engine, which causes the engine to accelerate.
When you step off of the accelerator pedal, the APP sensors send this info to the fuel injection computer. The computer now commands the actuator control motor to close the throttle plate. And the engine decelerates as less air enters it.
The accelerator pedal on your 3.5L Chevrolet Malibu or 3.5L Pontiac G6 comes equipped with two accelerator pedal position sensors. They are both part of one assembly that bolts on the accelerator pedal. These sensors are known as:
- Accelerator pedal position sensor (APP) sensor 1.
- Accelerator pedal position sensor (APP) sensor 2.
Each one is tasked with measuring the pedal angle and then transmitting this information to the fuel injection computer as an analog voltage signal. This voltage signal corresponds to the amount the accelerator pedal travels as you depress it.
The TP sensors (in the throttle body) also play their part and you can find out more about them here: Electronic Throttle Body Basics (2007-2009 3.5L Chevy Malibu And Pontiac G6).
You can take a look at the APP sensor assembly's circuits, on your 3.5L Chevrolet Malibu or 3.5L Pontiac G6, in the wiring diagrams found here: TAC Circuit Wiring Diagram (2007-2009 3.5L Chevy Malibu And Pontiac G6).
APP Sensor 1 Basic Operating Theory
APP sensor 1 gets power (in the form of 5 Volts DC) and Ground from the fuel injection computer to be able to produce its accelerator pedal position signal.
The APP sensor 1 signal is sent directly to your 3.5L V6 Chevrolet Malibu or Pontiac G6's fuel injection computer.
The following chart identifies the specific terminals of APP sensor 1:
| Pin | Wire Color | Description |
|---|---|---|
| D | BRN | Ground |
| E | DK BLU | APP Sensor 1 Signal |
| F | WHT/BLK | 5 Volts |
APP sensor's signal voltage is less than 1 Volt DC at rest (foot off of the accelerator pedal). The signal increases as the pedal is depressed to a maximum voltage of over 4 Volts DC.
APP Sensor 2 Basic Operating Theory
APP sensor 2 gets power (in the form of 5 Volts DC) and Ground from the fuel injection computer to be able to produce its accelerator pedal position signal.
The APP sensor 2 signal is sent directly to your 3.5L V6 Chevrolet Malibu or Pontiac G6's fuel injection computer.
| Pin | Wire Color | Description |
|---|---|---|
| A | PPL | Ground |
| B | LT BLU | APP Sensor 2 Signal |
| C | TAN | 5 Volts |
APP sensor's signal voltage is about 0.6 Volts DC at rest and increases to a maximum of more than 2 Volts as the accelerator pedal is depressed.
