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).

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.