How To Test The TPS (1992-1994 3.0L Ford Ranger)

The throttle position sensor (TPS) is probably one of the easiest sensors to test on your 3.0L V6 equipped Ford Ranger or Ford Aerostar.

And the best part is that you need no more than just a multimeter to be able to test it. In this tutorial explain the TPS test so that you can find out if it's defective or not.

Contents of this tutorial at a glance:

  1. Symptoms Of A Defective TPS.
  2. TEST 1: Testing The TPS 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.

En Español You can find this tutorial in Spanish here: Cómo Probar El Sensor TPS (1993-1994 3.0L Ranger) (at: autotecnico-online.com).

Symptoms Of A Defective TPS

The one thing that you can be sure of, when the throttle position sensor TPS fails, is that the check engine light will be nice and bright on your Ford Rangers instrument panel.

But this isn't the only symptom you're going to see. The following is a brief list of symptoms you'll see from a defective TPS.:

  1. One of the following TPS trouble codes stored in the fuel injection 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. Hesitation when accelerating the engine (specially under load).

TEST 1: Testing The TPS Signal With A Multimeter

How To Test The TPS (1992-1994 3.0L Ford Ranger)

We're gonna' start off by making sure that the TPS is generating a voltage signal that gets bigger as we open up the throttle.

Now, when we close the throttle plate, the voltage signal should decrease back to its original value.

The wire that feeds the TP signal to the fuel injection computer is the grey with white stripe (GRY/WHT) wire of the TPS connector.

In the illustration above, the GRY/WHT wire connects to the terminal identified with the number 2.

NOTA:The throttle position sensor must remain connected to its electrical connector for this test to work. For this reason, you are going to need either a back probe or a wire piercing probe. You can see an example of this tool here: Wire Piercing Probe.

OK, let's start:

  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.

  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 TP signal test result:


CASE 1: The TP signal voltage increased/decreased as you opened/closed the throttle plate. This is the correct test result and let you know that the TPS is working correctly on your Ford Ranger. The TPS itself is not the cause behind the problem on your Ford Ranger.

CASE 2: The TP signal voltage had blanks or skips as you opened/closed the throttle plate. This test result let 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, we need to make sure that the TP sensor is getting both power and Ground. For this test go to: TEST 2: Making Sure The TPS Is Getting 5 Volts And Ground.