How To Test The TPS With A Multimeter (2003-2006 2.4L Honda Accord)

Testing testing the throttle position sensor (TPS) on your 2.4L Honda Accord isn't difficult at all. And you don't need any expensive diagnostic equipment to do it!

In this tutorial, I'm gonna explain how to test it with a multimeter. With your test results, you'll be able to quickly find out if the TPS is functioning correctly or if it's bad.

All of the test steps are explained in a step-by-step manner so that you can quickly diagnose the throttle position sensor on your Honda Accord.

APPLIES TO: This tutorial applies to the following vehicles:

• 2.4L Honda Accord: 2003, 2004, 2005.

Symptoms Of A Bad Throttle Position Sensor

The throttle position sensor is a critical component of the engine management system. So when it fails, you'll definitely notice that something is wrong.

You'll see one of the following OBD II TPS diagnostic trouble codes illuminating the check engine light:

• P0122: Throttle Position Sensor Circuit Low Input.
• P0123: Throttle Position Sensor Circuit High Input.
• P1121: Throttle Position Sensor Signal Lower Than Expected.
• P1122: Throttle Position Sensor Signal Higher Than Expected.

You're also going to see one or more of the following symptoms:

• Engine hesitates when you step on the accelerator pedal.
• Lack of power when accelerating the vehicle.
• Bad gas mileage.
• Engine idle either too high or too low.
• Rough engine idle.
• The engine may start and immediately stall.
• The engine cranks but does not start.

Throttle Position Sensor (TPS) Circuit Descriptions

I'm sure you've already noticed that the throttle position sensor has three wires coming out of its pigtail connector.

Each wire has a specific role, and the table below gives a brief description of each:

Terminal	Wire	Description
1	Green with yellow stripe (GRN/YEL)	Ground (from PCM)
2	Red with black stripe (RED/BLK)	TPS Signal
3	Yellow with blue stripe (YEL/BLU)	5 Volts (from PCM)

Where To Buy The TPS And Save

The following links will help you comparison shop for the throttle position sensor (of known professional automotive brands- NO knock-offs):

TEST 1: Testing The TPS Voltage Signal

The very first thing that we're going to do to get our TPS diagnostic started, is to check the performance of the TP sensor.

This test involves connecting the multimeter to the TP sensor signal wire and checking to see if the signal increases/decreases as we open/close the throttle plate.

Right off the bat, this test will let us know if the throttle position sensor is functioning correctly or if it's having problems.

The wire that we're going to tap into to read the TP voltage signal is the one that I've labeled with the number 2 in the photo above. This wire is the red with black stripe (RED/BLK) wire of the connector.

IMPORTANT: The throttle position sensor must remain connected to its connector in order to access the signal in the wire. You'll need to use a back-probe on the connector or a wire-piercing probe on the wire. You can see what this tool looks like and where to buy it here: Goupchn 4mm Banana to Banana Plug Test Leads Kit (Amazon affiliate link).

Let's get started:

1. 1

   Place your multimeter in Volts DC mode.

2. 2

   Connect the red multimeter test lead to the red with black stripe (RED/BLK) wire of the TP sensor harness connector.
   
   I've labeled the RED/BLK wire with the number 2 in the photo above.
   
   NOTE: The TPS must remain connected to its connector to test the TPS voltage signal.

3. 3

   Connect the black multimeter test lead directly on the battery negative (-) post.

4. 4

   Turn the key ON but don't crank or start the engine.

5. 5

   Manually rotate the throttle plate to its open position.
   
   You'll get the best results by opening and closing the throttle plate directly on the throttle body instead of stepping on the accelerator pedal.

6. 6

   The multimeter should show an increasing voltage as you (or your helper) open up the throttle plate.

7. 7

   Close the throttle plate as you observer the multimeter.

8. 8

   The multimeter should show a decreasing voltage as you begin to close the throttle plate.

9. 9

   Using a screwdriver's handle, gently tap the TP sensor as you open and close the throttle plate and observe the multimeter.
   
   The purpose (of tapping the TP sensor with the screwdriver's handle) is to see if the TP sensor shows gaps in the voltage signal. Why? Because a good TP sensor will show a continuous increasing or decreasing voltage signal even while getting tapped by the screw-driver's handle.

Let's analyze your test results:

CASE 1: The TPS voltage signal increased/decreased as you opened/closed the throttle plate. This is the correct test result and it indicates that the throttle position sensor is good.

With this test result you can also conclude that the TPS sensor is getting both power (5 Volts) and Ground from the fuel injection computer.

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

To make sure the TPS sensor is bad the next step is to check that the YEL/BLU wire is feeding the TPS with 5 Volts. For this test go to: TEST 2: Making Sure The TPS Is Receiving 5 Volts.

CASE 3: The multimeter DID NOT register any voltage. This test result usually indicates that the TPS sensor is defective.

To make sure the TPS sensor is bad the next step is to check that the YEL/BLU wire is feeding the TPS with 5 Volts. For this test go to: TEST 2: Making Sure The TPS Is Receiving 5 Volts.

TEST 2: Making Sure The TPS Is Receiving 5 Volts

If you've reached this point, TEST 1 has confirmed that the throttle position sensor isn't creating a variable voltage signal as you open/close the throttle plate.

There's a good chance that it might not be receiving five Volts from the PCM. So in this test section, we're going to check that the wire I've labeled with the number 3 is delivering 5 Volts DC to the TPS.

To check for the presence of these 5 Volts in the wire, we'll do a simple multimeter voltage test.

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 the ON position but don't start the engine.

4. 4

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

5. 5

   With the red multimeter test lead, gently probe the female terminal that connects to the yellow with blue stripe (YEL/BLU) wire of the TPS connector.
   
   I've labeled the YEL/BLU wire the the number 3 in the photo above.

6. 6

   Your multimeter should read 4.5 to 5 Volts DC.

Let's analyze your test results:

CASE 1: The YEL/BLU wire is feeding the TPS with 5 Volts. This is the correct test result.

Now that you have confirmed the 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 YEL/BLU wire IS NOT feeding the TPS with 5 Volts. Without these 5 Volts the TPS will not function.

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

TEST 3: Making Sure That The TPS Is Receiving Ground

Up to this point you have confirmed two things:

• The throttle position sensor is not creating a voltage signal that increases/decreases as you open/close the throttle plate (TEST 1).
• The throttle position sensor is receiving 5 Volts from the PCM (TEST 2).

For our last test, we're going to make sure that the TPS is receiving Ground from the PCM.

This Ground is delivered to the throttle position sensor via the wire that I've labeled with the number 1 in the photo above.

As in the previous tests, we're going to use our multimeter to verify the presence of Ground in the wire.

IMPORTANT: Be careful not to short the Ground wire to battery power, or you'll fry the fuel injection computer. The multimeter voltage test suggested below (to test the Ground circuit) is a safe and accurate test.

These are the test steps:

1. 1

   Place your multimeter in Volts DC mode.

2. 2

   Disconnect the TPS from its electrical connector.

3. 3

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

4. 4

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

5. 5

   With the black multimeter test lead, gently probe the terminal that connects to the green with yellow stripe (GRN/YEL) wire of the TPS connector.
   
   In the photo above, I've labeled the GRN/YEL wire with the number 1.

6. 6

   Your multimeter should read 10 to 12 Volts DC.

Let's analyze your test results:

CASE 1: The GRN/YEL wire is feeding Ground to the TPS. This is the correct test result.

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

• Confirmed that the TPS voltage signal does not increase/decrease as you opened/closed 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 GRN/YEL wire IS NOT feeding Ground to the TPS. Without Ground the TPS will not function.

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

More 2.4L Honda Accord Tutorials

You can find a complete list of 2.4L Honda Accord diagnostic tutorials in this index:

• 2.4L Honda Accord Index of Articles.

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

• How To Test Misfire Trouble Codes (2003-2007 2.4L Honda Accord).
• How To Test The Fuel Injectors (2003-2007 2.4L Honda Accord).
• How To Test The Ignition Coils (2003-2007 2.4L Honda Accord).
• How To Test The MAP Sensor (2003-2007 2.4L Honda Accord).