How To Test The Throttle Position Sensor (3.4L V6 Chevrolet, Pontiac)

TEST 2: Making Sure The TPS Is Receiving 5 Volts

If your test result from TEST 1 indicates that the TPS voltage signal does not increase/decrease as you open/close the throttle plate, then there's a good chance that it isn't receiving 5 Volts DC from the fuel injection computer.

So in this test section we're going to make sure that the wire labeled with the letter A is delivering 5 Volts to the TPS.

The color of the wire that connects to the terminal labeled with the letter A is grey (GRY).

If the GRY wire is delivering 5 Volts DC, then the next step is to make sure that the TPS is receiving Ground (TEST 3).

Let's get testing:

1. 1

   Place your multimeter in Volts DC mode.

2. 2

   Disconnect the TPS from its electrical connector.

3. 3

   Turn the key on but don't start the engine.

4. 4

   With the red multimeter test lead (using the appropriate tool), gently probe the female terminal that connects to the wire labeled with the letter A.

5. 5

   Connect the black multimeter test lead to the negative (-) battery terminal.

6. 6

   Your multimeter should read 4.5 to 5 Volts DC.

Let's analyze your test results:

CASE 1: The GRY wire is feeding the TPS with 5 Volts. This is the correct result and it confirms that the TPS is receiving power.

Now that you've confirmed that your 3.4L V6 Chevrolet (Pontiac)'s TPS is getting 5 Volts, the next step is to make sure it's getting Ground. Go to: TEST 3: Making Sure That The TPS Is Receiving Ground.

CASE 2: The GRY wire IS NOT delivering 5 Volts. This is not good since without these 5 Volts, the TPS will not function.

These missing 5 Volts are usually the result of an open-circuit problem in the GRY wire between the TPS sensor's connector and the fuel injection computer's connector.

TEST 3: Making Sure That The TPS Is Receiving Ground

If you've reached this point, the previous two tests have confirmed that:

• The TPS voltage signal does not increase/decrease as you open/close the throttle plate (TEST 1).
• The TPS is receiving 5 Volts DC from the gray wire of the sensor's 3-wire connector (TEST 2).

For our last test we're going to make sure that the black (BLK) wire of the sensor's 3-wire connector is delivering Ground.

In the photo above, the BLK wire is labeled with the letter B.

IMPORTANT: Be careful and don't short the Ground wire to battery power or you'll fry the fuel injection computer. The multimeter voltage test suggested below (for testing the presence of Ground in the wire) is a safe and accurate test.

This is what you'll need to do:

1. 1

   Place your multimeter in Volts DC mode.

2. 2

   Disconnect the TPS from its electrical connector.

3. 3

   Turn the key on but don't start the engine.

4. 4

   With the black multimeter test lead (using the appropriate tool), gently probe the terminal that connects to the wire labeled with the letter B.

5. 5

   Connect the red multimeter test lead to the positive (+) battery terminal.

6. 6

   Your multimeter should read 10 to 12 Volts DC.

Let's analyze your test results:

CASE 1: Your multimeter registered 10 to 12 Volts DC. This is the correct and expected test result and it confirms that the BLK wire is delivering Ground to the TPS.

You can correctly conclude that the TPS is defective if you have:

• Confirmed that the TPS voltage signal does not increase/decrease as you open/close the throttle plate (TEST 1).
• Confirmed that the TPS is getting 5 Volts (TEST 2).
• Confirmed, in this test section, that the TPS is getting Ground.

CASE 2: The BLK wire IS NOT delivering Ground to the TPS. This is not good, since without Ground the TPS will not function.

This missing Ground is usually caused by an open-circuit problem in the BLK wire between the throttle position sensor's connector and the fuel injection computer's connector.

Your next diagnostic step is to find out why this Ground is missing and restore it to the wire. Once restored, the throttle position sensor will function again.

More 3.4L V6 Chevrolet, Pontiac Tutorials

You can find a complete list of 3.4L V6 Chevrolet (Pontiac) tutorials in this index:

• GM 3.4L Index Of Articles.

Here's a small sample of the tutorials you'll find in the index:

• How To Test Engine Compression Test (3.4L V6 Chevrolet, Pontiac).
• How To Test A Blown Head Gasket (3.4L V6 Chevrolet, Pontiac).
• What Does The CKP Sensor Do? (3.4L V6 Chevrolet, Pontiac).
• What Do The Spark Plugs Do? (3.4L V6 Chevrolet, Pontiac).