How To Test The Throttle Position Sensor (2.3L Ranger, Mustang, B2300)

TEST 1: Testing The TP Signal

To start our TPS diagnostic, the very first thing you'll do is to see if the throttle position sensor is creating a good TP signal the PCM can use.

As mentioned in the previous page, the throttle position sensor produces a voltage signal that increases as the throttle plate is opened and you're gonna' check this TP signal with a multimeter.

You'll need a helper to assist you in this test step, since you'll need someone to lightly tap on the throttle position sensor's body with a screw driver while you observe the multimeter and manually actuate the throttle.

OK, let's start testing:

1. 1

   Place your multimeter in Volts DC mode.

2. 2

   Connect the red test lead to the wire labeled with the number 2 of the TPS connector (see photo above).

3. 3

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

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 observe the multimeter.
   
   The purpose (of tapping the TP sensor with the screwdriver's handle) is to see if the TP sensor shows gaps 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 analyze your test results:

CASE 1: The multimeter registered a smooth increase or decrease in voltage. This is the correct test result and it tells you that the TP sensor is working OK and is not the cause of the TPS fault code issue.

If you're still having issues with the throttle position sensor or TPS trouble code, go to: The TPS Code Won't Go Away for a few more suggestions as to what could be causing the TPS diagnostic trouble code (DTC).

CASE 2: The multimeter DID NOT register a smooth increase or decrease in voltage. This usually means that you've got a bad throttle position sensor (TPS) on your hands.

To make sure that the TPS is bad, the next step is to make sure that it's getting 5 Volts from the fuel injection computer. For this test go to: TEST 2: Testing The 5 Volt Reference Signal.

TEST 2: Testing The 5 Volt Reference Signal

In this test step, you're gonna' make sure that the throttle position sensor is getting power.

This power comes in the form of 5 Volts and these 5 Volts come directly from the fuel injection computer.

We'll be checking this voltage with your multimeter.

This is what you'll need to do:

1. 1

   Place your multimeter in Volts DC mode.

2. 2

   Disconnect the TPS from its electrical connector.

3. 3

   Turn the key the ON position but don't start the engine.

4. 4

   Connect the red multimeter test lead (using the appropriate tool) to the wire labeled with the number 1.

5. 5

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

6. 6

   Your multimeter should read 4.5 to 5 Volts DC.

Let's analyze your test results:

CASE 1: The multimeter registered 4.5 to 5 Volts. This is the correct and expected test result and it confirms that the TPS is getting power.

It also tells you that the fuel injection computer and the wire that's supplying the TPS with power is OK. The next step is to make sure that the TPS is getting Ground, go to: TEST 3: Testing The Sensor Return (Ground) Circuit.

CASE 2: The multimeter DID NOT register 4.5 to 5 Volts. Then you've got a problem, since the computer or the circuit are NOT providing the voltage that the TPS on your 2.3L Ford Ranger or Mustang needs to operate.

The two most likely reasons for this are:

1. The wire is 'open' between the PCM and the TPS connector.
2. The PCM may be fried (this is rare but it does happen).

Altho' it's beyond the scope of this article to test these two conditions, you have now eliminated the throttle position sensor (TPS) on your 2.3L Ranger or 2.3L Mustang as being the cause of the problem and/or the TPS diagnostic trouble code (DTC) lighting up the check engine light (CEL).