TEST 2: Verifying Throttle Position Sensor Has Power

How To Test The Throttle Position Sensor (2.7L V6 Chrysler/Dodge)

If your test result in TEST 1 indicates that the TPS signal is not increasing/decreasing, then we need to make sure that the TPS is getting power and ground.

In this test section we're gonna' check that it's getting power. The violet with white stripe (VIO/WHT) wire of the TPS connector is the one that supplies power (5 Volts DC) to the sensor.

In case you're wondering, the PCM (Powertrain Control Module) is the one that supplies the throttle position sensor with these 5 Volts DC.

This is how we're gonna' check for these 5 Volts:

  1. 1

    Set your multimeter to Volts DC mode and turn the key on but don't crank or start the engine.

    This will power up the TP sensor's connector.

  2. 2

    With the RED multimeter lead probe the VIO/WHT wire of the TPS engine wiring harness connector.

    IMPORTANT Do not probe the front of the TPS connector. Probing the metal terminal of the TPS connector could damage it and require that you replace the connector. Use a back probe or a wire piercing probe instead of probing the front of the connector.

  3. 3

    Connect the BLACK multimeter lead to a good and clean ground point on the engine or directly on the negative (-) battery terminal.

  4. 4

    When you've set up the test, have a helper turn the Key On Engine Off (KOEO).

  5. 5

    Your multimeter should display 4.5 to 5 Volts on its screen.

Let's intrepet your test result:

CASE 1: Your multimeter confirms that the VIO/WHT wire is feeding the TPS with 4.5 to 5 Volts. This means that the throttle position sensor (TPS) is getting power from the fuel injection computer.

The next and last test, is to make sure that the throttle position sensor is getting ground (from the PCM too). For this test, go to: TEST 3: Verifying Throttle Position Sensor Has Ground.

CASE 2: Your multimeter confirms that the VIO/WHT wire IS NOT feeding the TPS with 4.5 to 5 Volts. Double check all of your connections and repeat the test. If your multimeter still doesn't register the 4.5 to 5 Volts DC...

.. then this test result tells you that the TPS itself is not at fault (and thus causing the TPS trouble code). Without power, the TPS can't create a throttle angle voltage signal. Although beyond the scope of this tutorial, your next step is to diagnose and restore this missing power.

TEST 3: Verifying Throttle Position Sensor Has Ground

How To Test The Throttle Position Sensor (2.7L V6 Chrysler/Dodge)

So far, you have confirmed several things:

  1. A TPS trouble code (P0121, P0122, or P0123).
  2. The TPS voltage signal does not increase/decrease according to throttle plate angle position (TEST 1).
  3. The VIO/WHT wire of the TPS engine wiring harness connector has power (TEST 2).

The last test we're gonna' do is to make sure that the BLK/LT BLU wire of the TPS connector is feeding the TPS with ground.

To verify the TPS is getting ground, we're going to do a simple voltage test on the BLK/LT BLU wire with our multimeter.

IMPORTANT: Ground is provided directly by the fuel injection computer. Be careful and don't intentionally or accidentally short this wire (circuit) to battery power or you will fry the fuel injection computer.

OK, here are the test steps:

  1. 1

    Set your multimeter to Volts DC mode.

  2. 2

    Probe the TPS connector's BLK/LT BLU wire with the BLACK multimeter lead.

    IMPORTANT: Avoid probing the front of the TPS connector. Probing the metal terminal of the TPS connector could damage it and require that you replace the connector. Use a back probe or a wire piercing probe instead of probing the front of the connector.

  3. 3

    Now, with the RED multimeter lead, probe the battery positive (+) terminal.

  4. 4

    Turn the Key to its ON position but don't start the engine. This will power up the fuel injection computer.

  5. 5

    Your multimeter will display 11 to 12 Volts if the BLK/LT BLU is feeding ground to the throttle position sensor (TPS).

Let's take a look at what your test results mean:

CASE 1: Multimeter displayed 11 to 12 Volts thus confirming that the BLK/LT BLU wire is feeding ground. This is the correct and expected test result and confirms the TPS is getting ground.

Taking into account the test results of all 3 test, you have confirmed that:

  1. The TP sensor is not providing a varying voltage signal when manually opening the throttle plate (TEST 1).
  2. The TP sensor is being fed 5 Volts DC (TEST 2).
  3. The TP sensor is being fed ground (TEST 3).

Therefore, you can conclude that the throttle position sensor is BAD and needs to be replaced (and that this will solve the TP sensor code lighting up the check engine light).

CASE 2: Multimeter DID NOT display 11 to 12 Volts thus confirming that the BLK/LT BLU wire IS NOT feeding ground. Double check that you're testing the correct TP sensor harness terminal wire and repeat the test.

If your test result still indicates that the TPS is not getting ground, then we can conclude that one of two things are causing this lack of ground:

  1. There's an open in the BLK/LT BLU wire between the TP sensor harness connector and the fuel injection computer's harness connector.
  2. The PCM has an internal problem (although this is extremely rare).

Although testing these two conditions are beyond the scope of this article, you have now eliminated the throttle position sensor (TPS) on your 2.7L Chrysler/Dodge as being the cause of the problem and/or the TP sensor diagnostic trouble code (DTC) lighting up the check engine light (CEL).