TEST 1: Testing The Power (5 Volt) Circuit

How To Test The Throttle Position Sensor (2.4L Mitsubishi)

OK, the first test, in your TPS diagnostic and troubleshooting, is to see if the throttle position sensor is indeed getting power.

Power comes in the form of 5 Volts. This voltage is provided internally by the PCM.

Alright, here's what you'll need to do:

  1. Once you have warmed up the engine, turn it off and remove any plastic covers that may be hiding the TPS from view and access.
  2. If necessary, remove the air duct that connects the throttle body to the mass air flow sensor assembly.
  3. Put your multimeter in Volts DC mode (don't have a digital multimeter? Need to buy one? Click here to see my recommendations: Buying A Digital Multimeter For Automotive Diagnostic Testing).
  4. With the red multimeter test lead, and an appropriate tool, probe the circuit labeled with the number 1 in the photo.
    1. The best way to probe this circuit is with a Wire Piercing Probe, to see what one looks like, click here: Wire Piercing Probe.
  5. Connect the black multimeter test lead to a good and clean Ground point on the engine or directly on the negative battery terminal.
  6. Turn the Key to its ON position but do not start the engine.
  7. Your multimeter should read 4.5 to 5 Volts.

Let's see what your multimeter test result means:

CASE 1: The multimeter registered 4.5 to 5 Volts. This is the correct and expected test result.

So far so good since this confirms that the PCM on your Mitsubishi (or Chrysler Sebring or Dodge Stratus) is feeding power to the TPS. The next step is to see if it's also feeding Ground, go to: TEST 2: Testing The Sensor Return (Ground) Circuit.

CASE 2: The multimeter DID NOT register 4.5 to 5 Volts. Without these 5 Volts the TPS won't work.

This usually happens when the fuel injection computer is NOT supplying power to the TPS. This missing voltage could be the result of an open-circuit problem in the circuit or the PCM may be fried.

Altho' testing these two conditions are beyond the scope of this article, you have now eliminated the throttle position sensor (TPS) on your Mitsubishi vehicle as being the cause of the problem and/or the TPS diagnostic trouble code (DTC) lighting up the check engine light (CEL).

TEST 2: Testing The Sensor Return (Ground) Circuit

How To Test The Throttle Position Sensor (2.4L Mitsubishi)

As you saw, testing for power was easy enough. Testing the Ground circuit is easy too since we'll perform the same multimeter voltage test on the Ground wire.

The wire that feeds the TPS sensor with Ground is the one labeled with the number 3 in the photo above.

Here's what you'll need to do:

  1. Place your multimeter in Volts DC mode.
  2. Probe the circuit labeled with the number 3 in the photo, with the black multimeter test lead.
  3. The red multimeter test lead goes to the battery positive terminal.
  4. Turn the Key to its ON position but don't start the engine.
  5. The multimeter should display 11 to 12 Volts..

Let's see what your test results mean:

CASE 1: The multimeter displayed 10 to 12 Volts. This is the correct test result. You can conclude that the fuel injection computer is feeding Ground to the throttle position sensor.

The next step is to check that the TP sensor is creating a good throttle position signal the PCM can use, go to: TEST 3: Testing The TP Signal.

CASE 2: The multimeter DID NOT display 10 to 12 Volts. Without Ground the TPS won't work.

This is usually happens when the PCM is NOT supplying a Ground either because of an internal fault/problem or there's an open in the wire between the TPS and the PCM itself. Altho' testing these two conditions are beyond the scope of this article, you have now eliminated the throttle position sensor (TPS) on your Mitsubishi vehicle as being the cause of the problem and/or the TPS diagnostic trouble code (DTC) lighting up the check engine light (CEL).

TEST 3: Testing The TP Signal

How To Test The Throttle Position Sensor (2.4L Mitsubishi)

OK, we've come to the test that'll let you know if the TPS is bad or not. Before you start, the engine has to be at its normal operating temperature. So, if the engine is cold, start 'er up and warm her up.

You'll need a helper to assist you in this test step, since he or she will need to lightly tap on the throttle position sensor's body with a screw driver (or other appropriate tool) while you observe the multimeter and manually actuate the throttle. OK, let's start testing:

Part 1

  1. Select Volts DC mode on your multimeter.
  2. Probe the circuit labeled with the number 2 in the photo with the red multimeter test lead, using an appropriate tool to pierce the wire.
  3. Ground the black multimeter test lead directly on the battery negative terminal.
  4. Turn the Key On with the engine Off.
  5. Your multimeter should register about 0.6 Volts DC.

Part 2

  1. Now that the multimeter is set up...
  2. Manually rotate the throttle plate by hand as you eye-ball the multimeter's voltage readings.
  3. The multimeter's initial voltage reading should increase smoothly as you open the throttle plate to its Wide Open Position. At Wide Open throttle, your multimeter should register 4.9 Volts DC.
  4. Now, slowly release the throttle plate to its fully closed position, all the while observing the multimeter's reading.
  5. The multimeter's voltage reading should decrease in a smooth and linear fashion and return to the voltage you observed in step 5 (about 0.6 Volts DC).

Part 3

  1. OK, now have your helper lightly tap the TP sensor with the butt of a screw-driver's handle (or something similar).
  2. As he or she taps, you need to slowly and smoothly open the throttle to its Wide Open position and then slowly release it back to its closed position.
  3. All the while you've got your eyes glued on the multimeter to see if the tapping affects the voltage readings.
  4. Repeat this (tapping the throttle position sensor) several times to make sure of your results.

Interpreting The Results

If the throttle position sensor (TPS) is working correctly, the multimeter will register a smooth increase in the DC voltage until the maximum voltage is reached, which is about 4.5 Volts DC. Then, as you slowly release the throttle plate back to its closed position, the multimeter will display a gradual decrease in voltage till the initial base voltage is achieved (which you recorded in the beginning of the test).

If the TPS is bad, then there will be sudden gaps/loss of voltage or the voltage reading will jump around crazily as you increase or decrease the throttle plate's to its fully open or fully closed position, especially when you tap on the sensor. Or, there will be no voltage reading at all. OK then, here are the two possible outcomes:

CASE 1: The multimeter registered a smooth increase or decrease in voltage. This is the correct test result.

You can conclude that the throttle position sensor is good and not the cause of the TPS fault code issue. Go to: TEST 4: TPS Code Won't Go Away for a few more suggestions as to what could be causing the TPS diagnostic trouble code (DTC).

CASE 2: The multimeter DID NOT register a smooth increase or decrease in voltage. With this test result you can conclude that the throttle position sensor (TPS) is bad. Replacing the throttle position sensor will solve the TPS diagnostic trouble code (DTC) lighting up your check engine light (CEL) on your Mitsubishi (or Chrysler Sebring or Dodge Stratus) vehicle.

Chrysler Vehicles:

  • Sebring 2.4L (SOHC)
    • 2001, 2002, 2003, 2004, 2005

Dodge Vehicles:

  • Stratus 2.4L (SOHC)
    • 2001, 2002, 2003, 2004, 2005

Mitsubishi Vehicles:

  • Eclipse 2.4L (SOHC)
    • 2001, 2002, 2003, 2004, 2005

Mitsubishi Vehicles:

  • Galant 2.4L (SOHC)
    • 1999, 2000, 2001, 2002, 2003, 2004, 2005