TEST 2: Verifying Throttle Position Sensor Has Power

Making Sure The Throttle Position Sensor Is Getting 5 Volts (1996-1997 2.4L Nissan Altima)

If you've reached this point, you have confirmed that in TEST 1 the TPS did not create the correct throttle angle voltage signal. To make sure that this test result is not due to a lack of power (to the TPS), in this test step we'll check that the TPS is indeed being fed with 5 Volts.

The wire that feeds the TP sensor with 5 Volts DC is the red with yellow stripe (RED/YEL) wire of the brown connector. This RED/YEL wire is the one that connects to female terminal number 3 in the illustration above.

NOTE: Be careful when probing the female terminals of the TPS connector with the multimeter test leads. I suggest that you use a back probe on the connector or a wire piercing probe on the wire. You can see an example of this tool here: Wire Piercing Probe.

Alight, these are the test steps:

  1. 1

    Disconnect the TPS from its electrical connector.

  2. 2

    Place your multimeter's dial in Volts DC mode.

  3. 3

    Turn the key on but don't start the engine.

    This will power up the TP sensor's connector.

  4. 4

    Connect the red multimeter test lead to the RED/YEL wire of the brown TPS connector.

    This wire connects to the female terminal labeled with the number 3 in the illustration above.

    IMPORTANT Be careful when probing the female terminal of the TPS connector. Damaging the terminal will require that you replace the connector. Use a back probe or a wire piercing probe instead of probing the front of the connector.

  5. 5

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

  6. 6

    When you've set up the test, have a helper turn the key on but don't crank or start the engine.

  7. 7

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

Let's examine your test results:

CASE 1: The RED/YEL wire has 4.5 to 5 Volts. So far so good since this tells you that the throttle position sensor (TPS) is getting power from the powertrain control module (PCM).

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: The RED/YEL wire DOES NOT have 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. Without power, the TPS can't create a throttle angle voltage signal.

Although it's 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

Making Sure The Throttle Position Sensor Is Getting Ground (1996-1997 2.4L Nissan Altima)

In this test step, we're gonna' make sure that the black (BLK) wire of the brown TPS connector is feeding the TPS with Ground.

The BLK wire connects to the female terminal labeled with the number 1 in the illustration above.

IMPORTANT: The PCM is the one that feeds this Ground to the throttle position sensor (TPS). Be careful and don't short this wire to battery voltage or you'll fry the PCM.

OK, here are the test steps:

  1. 1

    Disconnect the TPS from its electrical connector.

  2. 2

    Set your multimeter to Volts DC mode.

  3. 3

    Connect the black multimeter test lead to the BLK wire of the brown TPS connector.

    This wire connects to the female terminal labeled with the number 1 in the illustration above.

    Be careful not to damage the female terminal if you probe it on the front of the connector. If possible, you should use a back probe or a wire-piercing probe to check this circuit.

  4. 4

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

  5. 5

    Turn the key to its ON position but don't start the engine. This will power up the PCM.

  6. 6

    Your multimeter should display 10 to 12 Volts if the BLK wire is feeding the TPS with Ground.

Let's interpret your multimeter test results:

CASE 1: The multimeter showed 10 to 12 Volts. This tells you that the throttle position sensor, on your Nissan Altima, is being fed with Ground from the PCM.

All three test have confirmed that:

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

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 show 10 to 12 Volts. Double check that you're testing the correct TP sensor harness terminal wire and repeat the test.

If your multimeter still doesn't show the indicated voltage, then we can conclude that there's an open in the wire between the TP sensor harness connector and the PCM's harness connector. In the extreme of cases, the PCM has an internal problem (although this is very rare).

Although testing these two conditions are beyond the scope of this article, you have now eliminated the throttle position sensor (TPS) on your 2.4L Nissan Altima as being the cause of the problem and/or the TP sensor diagnostic trouble code (DTC) lighting up the check engine light (CEL).

Nissan Vehicles:

  • Altima 2.4L (w/ AT Trans)
    • 1996,
      1997