How To Test The TPS With A Multimeter 1994-1995 3.8L Ford Taurus, 1994-1995 3.8L Ford Mercury Sable, 1995 3.8L Ford Windstar)

The throttle position sensor (TPS) in the 1994 through 1995 3.8L Ford Taurus (Mercury Sable) can be tested easily.

The test involves three specific steps. In the first one, we're gonna' make sure that the TPS is producing a TP signal that corresponds to the throttle plate angle.

The other two tests are to make sure that the TPS is receiving 5 Volts and Ground. From the results of these 3 tests, you'll be able to correctly conclude that the TPS is defective or not.

NOTE: This tutorial also applies to the TPS of the 1994-1995 3.8L V6 Mercury Sable and 1995 3.8L V6 Ford Windstar mini-van.

  1. Symptoms Of A Defective TPS.
  2. TEST 1: Testing The TP Signal With A Multimeter.
  3. TEST 2: Making Sure The TPS Is Getting 5 Volts And Ground.
  4. TPS Trouble Code Won't Go Away.
  5. Where To Buy The TPS And Save.
  6. More Ford 3.8L Tutorials.

NOTE: You'll notice in the illustration I'm using in this tutorial that there are two different types of TP sensors. The difference being that starting in the 1995 model year the the connector changed with the introduction of the OBD II system. This tutorial covers both types of TP sensors.

En Español You can find this tutorial in Spanish here: Cómo Probar El Sensor TPS (1994-1995 3.8L Taurus) (at: autotecnico-online.com).

Symptoms Of A Defective TPS

Your 3.8L Ford Taurus' fuel injection computer needs to know the throttle plate angle to effectively manage engine performance.

This throttle plate angle changes continually as you step on or off the accelerator pedal (since the accelerator pedal is connected to the throttle bodies throttle plate via a accelerator cable).

The fuel injection computer uses this information (throttle angle), along with other sensor inputs, to: inject more/less gasoline, advance/retard ignition timing, etc.

So, when the throttle position sensor fails, your Ford Taurus' engine performance will suffer and you're gonna' see one of the following symptoms:

  1. The check engine light (CEL) lit by one or more of the following trouble codes stored in the computer's memory.
    1. 43: Throttle Position (TP) Sensor Below Idle Specification.
    2. 53: Throttle Position (TP) Sensor Above Maximum Voltage.
    3. 63: Throttle Position (TP) Sensor Below Minimum Voltage.
  2. Bad gas mileage.
  3. Lack of power when you accelerate the vehicle down the road.
  4. The engine hesitates when you accelerate the engine under load.

TEST 1: Testing The TP Signal With A Multimeter

Testing The TP Signal With A Multimeter. How To Test The TPS With A Multimeter 1994-1995 3.8L Ford Taurus, 1994-1995 3.8L Ford Mercury Sable, 1995 3.8L Ford Windstar)

The very first test we're gonna' do is to verify that the TPS is generating a signal that corresponds with the throttle plate angle.

To give you a few more details, we're gonna' check the TPS signal voltage when the throttle plate is in its closed position. Then as we open the throttle plate, this voltage signal should increase till the throttle plate reaches its maximum open position.

Now, when the throttle plate is in its closed position, the TP sensor should produce a voltage of about 0.5 to 0.9 Volts DC. In it wide open throttle position, the TPS should produce a voltage of about 4.5 to 4.9 Volts DC.

If the TPS is defective, you'll generally see that the voltage of value will stay stuck in one value irregardless of the throttle plate angle.

The wire that we'll be testing is the grey with white stripe (GRY/WHT) wire. In the illustration above, this wire connects to the TPS terminal labeled with the number 2.

NOTE: The throttle position sensor must remain connected to its electrical connector to be able to test the TP signal. For this reason you will need to use a back probe or a wire piercing probe to access the signals voltage inside the cable. You can see an example of a wire piercing probe here: Wire Piercing Probe (at: easyautodiagnostics.com).

These are the test steps:

  1. 1

    Place your multimeter in Volts DC mode and connect the red test lead to the GRY/WHT wire of the TP sensor harness connector.

    The GRY/WHT wire connects to the TPS terminal identified with the #2 in the illustration above.

  2. 2

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

  3. 3

    Turn the key on but don't crank or start the engine. This will power up the TPS.

  4. 4

    Manually rotate the throttle.

    You'll get the best results by opening and closing the throttle directly on the throttle body instead of stepping on the accelerator pedal.

  5. 5

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

    You'll get the best results by opening and closing the throttle directly on the throttle body instead of stepping on the accelerator pedal.

  6. 6

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

  7. 7

    Using a screwdriver's handle, gently tap the TP sensor as you open and close the throttle and observer the multimeter.

    The purpose (of tapping the TP sensor with the screwdriver's handle) is to see if the TP sensor shows gap's 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 take a look at your test results:


CASE 1: The TP signal voltage increased/decreased as you opened/closed the throttle plate. This is the correct test result and lets you know that the TPS is working correctly. The TPS itself is not the cause behind the problem on your 3.8L Ford Taurus (Mercury Sable).

CASE 2: The TP signal voltage had blanks or skips as you opened/closed the throttle plate. This test result lets you know that the throttle position sensor is defective.

CASE 3: The TPS voltage signal stayed stuck at one value when you opened/closed the throttle plate. This test result generally tells you that the TP sensor is defective.

To make sure that it is defective, the next step is to make sure the TPS has power and Ground. For this test go to: TEST 2: Making Sure The TPS Is Getting 5 Volts And Ground.