APP Sensor Tests (2005-2009 3.5L Chevy Malibu And Pontiac G6)

In this tutorial, I'm gonna' show you how to test APP sensor 1 and APP sensor 2 of the accelerator pedal assembly.

Each APP sensor can be tested with 3 easy multimeter resistance tests and in this tutorial, you'll find them explained in a step-by-step manner.

With your test results you'll be able to correctly diagnose the APP sensor assembly as defective or not.

NOTE: This tutorial applies to the following vehicles:

• 2005, 2006, 2007, 2008, 2009 3.5L V6 Chevrolet Malibu.
• 2005, 2006, 2007, 2008, 2009, 2010 3.5L V6 Pontiac G6.

You can find this tutorial in Spanish here: Cómo Probar El Sensor APP (2007-2009 3.5L Chevrolet Malibu y Pontiac G6) (at: autotecnico-online.com).

NOTE: The following electronic throttle body test tutorial and TAC system wiring diagrams, with the APP sensor circuits, may come in handy:

• Accelerator Pedal Position Sensor Basics (2007-2009 3.5L Chevy Malibu And Pontiac G6).
• Electronic Throttle Body Tests (2007-2009 3.5L Chevrolet Malibu And Pontiac G6).
• Throttle Body (TAC) Circuit Wiring Diagram (2007-2009 3.5L Malibu).
• Throttle Body (TAC) Circuit Wiring Diagram (2004-2006 3.5L Malibu).

Symptoms Of A Bad APP Sensor

As you're already aware, the accelerator pedal position sensor assembly is made up of two APP sensors: accelerator pedal position (APP) sensor 1 and accelerator pedal position (APP) sensor 2.

When one or both fail, you're gonna' see one or more of the following symptoms:

• The check light engine light will be lit up by one of the following trouble codes:
  • P2120: Accelerator Pedal Position (APP) Sensor 1 Circuit.
  • P2122: Accelerator Pedal Position (APP) Sensor 1 Circuit Low Voltage.
  • P2123: Accelerator Pedal Position (APP) Sensor 1 Circuit High Voltage.
  • P2125: Accelerator Pedal Position (APP) Sensor 2 Circuit.
  • P2127: Accelerator Pedal Position (APP) Sensor 2 Circuit Low Voltage.
  • P2128: Accelerator Pedal Position (APP) Sensor 2 Circuit High Voltage.
  • P2138: Accelerator Pedal Position (APP) Sensor 1 - 2 Correlation.
• Your Chevy Malibu (Pontiac G6) will run in Reduced Engine Power mode.
• The engine starts and runs but when you try to accelerate your Chevy Malibu (Pontiac G6), it accelerates very slowly.
• The engine starts and runs but the engine does not accelerate when you step on the accelerator pedal.
• The engine starts and runs but shuts down.

The cool thing is testing the accelerator pedal position sensors is not difficult at all. All you'll need is a multimeter and in this tutorial, I'll explain how to test both APP sensor 1 and APP sensor 2.

NOTE: You can find out more about how the APP sensors work here: Accelerator Pedal Position Sensor Basics (2007-2009 3.5L Chevy Malibu And Pontiac G6).

APP Sensor Terminal Pin Out Chart

The engine wiring harness connector (of the APP sensor assembly) has 6 wires coming out of it and it has female type terminals.

The connector on the APP sensor assembly itself has 6 male spade terminals. The illustration above is of the connector on the APP sensor assembly itself.

Pin	Wire Color	Description
A	PPL	Sensor Ground
B	LT BLU	APP Sensor 2 Signal
C	TAN	5 Volts
D	BRN	Sensor Ground
E	DK BLU	APP Sensor 1 Signal
F	WHT/BLK	5 Volts

Both accelerator pedal positions sensors are the potentiometer type, which means we can easily test them with a multimeter. Let's get started with the first test.

WIRING DIAGRAM: You can the APP sensor circuit wiring diagram here: TAC Circuit Wiring Diagram (2007-2009 3.5L Chevy Malibu And Pontiac G6).

Where To Buy The APP Sensor Assembly And Save

The following links will help you comparison shop for the APP sensor assembly for the 2007-2008 3.5L Chevrolet Malibu and 2007-2010 Pontiac G6:

Not sure if the APP sensor assembly will fit your particular GM vehicle? Don't worry, once you get to the site, they'll make sure it fits. If it doesn't, they'll find you the right one.

TEST 1: Testing The Resistance Between Terminals D And F (APP Sensor 1)

The first test we're gonna' start off with is making sure that the there's continuity between terminal D and F of APP sensor 1.

Terminal D is the terminal that gets Ground from your Chevy Malibu or Pontiac G6's fuel injection computer.

Terminal F is the terminal that gets 5 Volts from your Chevy Malibu or Pontiac G6's fuel injection computer.

NOTE 1: All multimeter connections are done on the male spade terminals of the APP sensor assembly itself.

NOTE 2: To make it easier to connect your multimeter test leads to the APP sensor assembly's terminals (and depress/release the accelerator pedal), I recommend that you use insulated alligator terminals on the ends of your multimeter test leads.

These are the test steps:

1. 1

   Disconnect the APP sensor assembly from its electrical connector.

2. 2

   Place your multimeter in Ohms mode.

3. 3

   Connect the red multimeter test lead to terminal D.

4. 4

   Connect the black multimeter test lead to terminal F.

5. 5

   Your multimeter should read continuity.
   
   In my test result, I got 1.2 K Ohms for the resistance reading.

Let's examine your test results:

CASE 1: The multimeter registered continuity between terminals D and F. This is the correct test result.

The next step is to test the continuity of terminals E and F (of APP sensor 1) while we depress/release the accelerator pedal. For this test go to: TEST 2: Testing The Resistance Between Terminals E And F (APP Sensor 1).

CASE 2: The multimeter DID NOT register continuity between terminals D and F. This lets you know that APP sensor 1 is bad. With this test result you can conclude that the APP sensor assembly is defective and needs to be replaced.