TEST 2: Verifying Throttle Position Sensor Has Power

Verifying Throttle Position Sensor Has Power. How To Test The Throttle Position Sensor (1998, 1999, 2000 3.0L Dodge/Plymouth Mini-Van)

Like every other electrical component on your mini-van, the throttle position sensor needs power and Ground to function.

Power is supplied directly by your mini-van's PCM. The TPS connector wire that feeds this power (5 Volts DC) is the VIO/WHT wire.

In this this test section we're gonna' verify that these 5 Volts are present by doing a simple multimeter voltage test.

Here are the test steps:

  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 test lead probe the VIO/WHT wire of the TPS engine wiring harness connector.

    IMPORTANT: Use a back probe or a wire piercing probe instead of probing the front of the connector. Probing the front of the TPS connector with your multimeter's test lead will damage it!

  3. 3

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

  4. 4

    Have your helper turn the key ON but don't start or crank the engine.

  5. 5

    Your multimeter will report 4.5 to 5 Volts DC if the VIO/WHT wire has power,.

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

CASE 1: Your multimeter confirms that the VIO/WHT 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 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

Verifying Throttle Position Sensor Has Ground. How To Test The Throttle Position Sensor (1998, 1999, 2000 3.0L Dodge/Plymouth Mini-Van)

If you've reached this point, you have:

  • A TPS trouble code (P0121, P0122, or P0123) is lighting up the check engine light.
  • Confirmed that the TPS is not creating the correct throttle plate angle voltage signal (TEST 1).
  • Confirmed that the VIO/WHT wire has 4.5 to 5 Volts DC.

Now, we need to verify that the BLK/LT BLU wire of the TPS connector is feeding Ground to the sensor.

This is another simple voltage test that we'll do with our multimeter in Volts DC mode.

IMPORTANT: Ground is provided directly by your mini-van's PCM. Be careful and don't intentionally or accidentally short this wire (circuit) to battery power or you will fry the PCM.

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 test lead.

    IMPORTANT: Use a back probe or a wire piercing probe instead of probing the front of the connector. Probing the front of the TPS connector with your multimeter's test lead will damage it!

  3. 3

    Now, with the red multimeter test 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 10 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: The multimeter displayed 10 to 12 Volts thus confirming that the BLK/LT BLU 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 10 to 12 Volts thus confirming that the BLK/LT BLU 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 3.0L V6 Caravan (Grand Caravan, Voyager, Grand Voyager) as being the cause of the problem and/or the TP sensor diagnostic trouble code (DTC) lighting up the check engine light (CEL).

Dodge Vehicles:

  • Caravan 3.0L
    • 1998, 1999, 2000
  • Grand Caravan 3.0L
    • 1998, 1999, 2000

Plymouth Vehicles:

  • Grand Voyager 3.0L
    • 1998, 1999, 2000
  • Voyager 3.0L
    • 1998, 1999, 2000