How To Test The TPS (1993-1996 2.2L Buick Century, Oldsmobile Cutlass Ciera)

Testing the throttle position sensor (TPS) is not difficult. In this tutorial, I'll explain how you can test it with a multimeter.

You'll easily and quickly determine whether TPS is good or bad with your test results.

ES You can find this tutorial in Spanish here: Cómo Probar El Sensor TPS (1993-1996 2.2L Buick Century, Oldsmobile Cutlass Ciera) (at: autotecnico-online.com).

APPLIES TO: This tutorial applies to the following vehicles:

• 2.2L Buick Century: 1993, 1994, 1995, 1996.
• 2.2L Oldsmobile Cutlass Ciera: 1993, 1994, 1995.
• 2.2L Oldsmobile Ciera: 1996.

Symptoms Of A Bad Throttle Position Sensor

As you're probably already aware, the accelerator pedal is connected to the throttle plate (in the throttle body) with an accelerator cable.

The throttle cable causes the throttle plate to open or close as you step on or off the accelerator pedal.

As the throttle plate opens, more air enters the engine, and the fuel injection computer has to increase the amount of fuel it's injecting into it (the engine).

The fuel injection computer becomes aware of the throttle plate angle through the throttle plate angle information provided by the throttle position sensor.

When the throttle position sensor fails, the fuel injection computer will set one of the following diagnostic trouble codes and illuminate the check engine light.

OBD I equipped vehicles:

• Code 21: Throttle Position Sensor (TPS) Signal Voltage High.
• Code 22: Throttle Position Sensor (TPS) Signal Voltage Low.

OBD II equipped vehicles:

• P0121: Throttle Position (TP) Circuit Performance Problem.
• P0122: Throttle Position (TP) Circuit Low Input.
• P0123: Throttle Position (TP) Circuit High Input.

You'll also see one or more of the following symptoms:

• Hesitation when accelerating the engine.
• Lack of power.
• Bad gas mileage.

Where To Buy The TPS And Save

The following links will help you to comparison shop for the throttle position sensor of known automotive brands (no knock-off sensors):

Not sure if the above TPS fits your particular vehicle? Don't worry, once you get to the site they'll make sure it fits by asking you the specifics of your particular vehicle. If it doesn't fit, they'll find you the right one.

TEST 1: Testing The TPS Voltage Signal

The TPS produces a voltage signal that increases as you open the throttle plate and decreases as the throttle plate closes.

Thankfully, we can use a multimeter to confirm that the TPS voltage signal increases/decreases as the throttle plate opens/closes.

Usually, when the TPS fails, it usually stays stuck, producing a single voltage value as the throttle plate opens/closes.

NOTE: You'll need a multimeter to be able to test the throttle position sensor. If you don't have one, check out my recommendations here: Tekpower TP8268 AC/DC Auto/Manual Range Digital Multimeter (Amazon affiliate link).

OK, let's start:

PART 1:

1. 1

   Turn the key to the ON position but don't start the engine.

2. 2

   Place your multimeter in Volts DC mode.

3. 3

   Connect the red multimeter test lead to the blue (BLU) wire of the TP sensor harness connector.
   
   The BLU wire is identified with the letter C in the photo above.

4. 4

   Connect the black multimeter test lead to the battery negative (-) terminal.
   
   NOTE: The TP sensor must remain connected to its electrical connector. You'll need to use a back probe or a wiring piercing probe to tap into the signal of the middle wire. To see what a wire piercing probe looks like and where to buy one, go here: Goupchn 4mm Banana to Banana Plug Test Leads Kit (Amazon affiliate link).

5. 5

   Your multimeter should report a voltage between 0.2 to 0.9 Volts DC with the throttle plate closed.
   
   If your multimeter doesn't, don't worry about it just yet, continue with the other steps.

PART 2:

1. 6

   Slowly open the throttle plate (by hand from the engine compartment).

2. 7

   The voltage value should increase as the throttle plate opens.
   
   This increase in voltage should be smooth and without any gaps or skips.
   
   Once the throttle is wide open, your multimeter should read somewhere between 3.5 to 4.5 Volts DC.

3. 8

   Slowly close the throttle plate.

4. 9

   As the throttle plate is closing, you should see the voltage decrease smoothly and without any gaps or skips, to the same voltage you noticed in step 3.

5. 10

   Lightly tap on the throttle position sensor with the handle of a screw-driver or something similar (I want to emphasize the words 'lightly tap') as you slowly open and close the throttle and observe the multimeter.
   
   If the TPS is bad, the tapping will cause the voltage numbers to skip or go blank. If the TPS is OK, the tapping will have no effect on the voltage numbers.

6. 11

   Repeat step 10 several times to make sure of your multimeter test results.

Let's take a look at your test results:

CASE 1: The TPS signal voltage increased/decreased as you opened/closed the throttle plate. This is the correct test result. It tells you that the throttle position sensor IS NOT defective.

This test result also confirms that the TPS is getting both power and Ground from the fuel injection computer.

CASE 2: The TPS signal voltage DID NOT increase/decrease as you opened/closed the throttle plate. This test result usually tells you that the TPS is bad.

So that you can make sure the TPS is bad, you need to make sure it's getting power and Ground. Go to: TEST 2: Making Sure The TPS Is Receiving 5 Volts.

CASE 3: The multimeter DID NOT register any voltage. This test result doesn't condemn the TP sensor as bad just yet.

Why? Because the TP sensor may be missing either power or Ground. So your next step is to check that the TP sensor is getting power and Ground. Go to: TEST 2: Making Sure The TPS Is Receiving 5 Volts.

TEST 2: Making Sure The TPS Is Receiving 5 Volts

Like any other electrical component, the throttle position sensor needs power to function.

This power is in the form of 5 Volts DC and are supplied by your vehicle's fuel injection computer.

The wire that delivers these 5 Volts to the TPS is the gray (GRY) wire of the sensor's 3-wire connector.

In the photo above, I've labeled the GRY wire with the letter A.

These are the test steps:

1. 1

   Select Volts DC mode on your multimeter.

2. 2

   Disconnect the TP sensor from its connector.

3. 3

   Gently probe the female terminal that connects to the grey (GRY) wire with the red multimeter test lead.
   
   The GRY wire is labeled with the letter A in the photo above.
   
   NOTE: Be careful not to damage the female terminal.

4. 4

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

5. 5

   When everything is set up, have a helper rotate the key to its ON position but don't start the engine.

6. 6

   The multimeter should report 4.5 to 5 Volts DC.

Let's interpret your test results:

CASE 1: The GRY wire is delivering 4.5 to 5 Volts. This is the correct and expected test result and lets you know the TPS is getting power.

Your next and last step is to make sure the TPS is getting Ground. Go to: TEST 3: Making Sure The TPS Is Receiving Ground.

CASE 2: The GRY wire IS NOT delivering 4.5 to 5 Volts. Double check your connections and make sure you're testing the correct wire.

If the GRY wire is still not delivering 5 Volts DC, you can conclude that the TPS is not creating its signal due to a lack of power.

The most likely cause of this missing voltage is an open-circuit problem in the GRY wire. Your next step is to find out why this voltage is missing and restore it.

TEST 3: Making Sure The TPS Is Receiving Ground

So far, your test results have confirmed:

• The TPS voltage signal does not increase/decrease as you open/close the throttle plate (TEST 1).
• The GRY wire is delivering 5 Volts to the TP sensor (TEST 2).

In this last test section, you'll make sure that the black (BLK) wire of the sensor's 3-wire connector is delivering Ground.

You'll confirm the presence of Ground in the BLK wire with a simple multimeter voltage test.

Let's get started:

1. 1

   Select Volts DC mode on your multimeter.

2. 2

   Disconnect the TP sensor from its connector.

3. 3

   Gently probe the female terminal that connects to the black (BLK) wire with the black multimeter test lead.
   
   The BLK wire is labeled with the letter B in the photo above.
   
   NOTE: Be careful not to damage the female terminal.

4. 4

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

5. 5

   When everything is set up, have a helper rotate the key to its ON position but don't start the engine.

6. 6

   The multimeter should display 10 to 12 Volts DC.

Let's interpret your test results:

CASE 1: Your multimeter registered 10 to 12 Volts. This is the correct and expected test result and confirms the TPS is getting Ground.

You can conclude that the TPS is bad and needs replacement if you have:

• Confirmed that the TP sensor is not producing a voltage signal that increases/decreases when you open/close the throttle plate (TEST 1).
• Confirmed that the TP sensor is receiving 4.5 to 5 Volts (TEST 2).
• Confirmed that the TP sensor is receiving Ground (this test section).

CASE 2: Your multimeter DID NOT register 10 to 12 Volts. Double check your connections and make sure you're testing the correct wire.

If the BLK wire is still not delivering Ground, you can conclude that the TPS is not creating its signal due to a lack of Ground.

The most likely cause of this missing Ground is an open-circuit problem in the BLK wire. Your next step is to find out why this Ground is missing and restore it.

More 2.2L Buick Century And Oldsmobile Cutlass Ciera Test Tutorials

If this tutorial was helpful, be sure and take a look at all of the 2.2L Buick Century and Oldsmobile Cutlass Ciera diagnostic tutorials in this index:

• GM 2.2L Index Of Articles.

Here's a sample of the tutorials you'll find there:

• How To Test The Fuel Pump (1993-1996 2.2L Buick Century, Oldsmobile Cutlass Ciera).
• How To Test The EGR Valve (1993-1995 2.2L Buick Century, Oldsmobile Cutlass Ciera).
• How To Test Engine Compression (1993-1996 2.2L Buick Century, Oldsmobile Cutlass Ciera).
• How To Test The MAP Sensor (1993-1996 2.2L Buick Century, Oldsmobile Cutlass Ciera).