Wednesday, 15 April 2015

how to replace Throttle position sensor on 2000 ford expedition

Ford TPS Sensor Replacement

Throttle Position Sensor

The Throttle Position (TP) sensor is a potentiometer that provides a signal to the PCM that is directly proportional to the throttle plate position. The TP sensor is mounted on the side of the throttle body and is connected to the throttle plate shaft. The TP sensor monitors throttle plate movement and position, and transmits an appropriate electrical signal to the PCM. These signals are used by the PCM to adjust the air/fuel mixture, spark timing and EGR operation according to engine load at idle, part throttle, or full throttle. The TP sensor is not adjustable.
The TP sensor receives a 5 volt reference signal and a ground circuit from the PCM. A return signal circuit is connected to a wiper that runs on a resistor internally on the sensor. The further the throttle is opened, the wiper moves along the resistor, at wide open throttle, the wiper essentially creates a loop between the reference signal and the signal return returning the full or nearly full 5 volt signal back to the PCM. At idle the signal return should be approximately 0.9 volts.

Removal & Installation

  1. Remove the throttle body (TB).
    Failure to remove the TP sensor screws in the following manner will result in damage to the screws. First loosen the screws 1-2 full turns using a hand tool and then use a suitable high speed driver to complete the removal.
  2. Remove and discard the screws and the TP sensor.
    Do not reuse the TP sensor and screws. A new TP sensor and screws must be installed.

    When installing the new TP sensor, make sure that the radial locator tab on the TP sensor is aligned with the radial locator hole on the throttle body.
  3. To install, reverse the removal procedure and note the following:
    1. Tighten the new sensor screws to 27 inch. lbs. (3 Nm).
5.4L & 6.8L Engines
  1. Disconnect the battery ground cable.
  2. Loosen the clamp and position the air cleaner outlet tube aside.
  3. Remove the accelerator cable snow shield.
  4. To remove the throttle position (TP) sensor.
    1. Disconnect the electrical connector.
    2. Remove the screws.
    3. Remove the TP sensor.
  5. To install, reverse the removal procedure.


Click image to see an enlarged view
Fig. TESTING the TP sensor signal return voltage at idle

Click image to see an enlarged view
Fig. Test the operation of the TP sensor by gently opening the throttle while observing the signal return voltage. The voltage should move smoothly according to the amount the throttle is opened

Click image to see an enlarged view
Fig. TESTING the supply voltage at the TP sensor connector

Click image to see an enlarged view
Fig. The TP sensor can be monitored with an appropriate and Data-stream capable scan tool
  1. With the engine OFF and the ignition ON, check the voltage at the signal return circuit of the TP sensor by carefully backprobing the connector using a DVOM.
  2. Voltage should be between 0.2 and 1.4 volts at idle.
  3. Slowly move the throttle pulley to the wide open throttle (WOT) position and watch the voltage on the DVOM. The voltage should slowly rise to slightly less than 4.8v at Wide Open Throttle (WOT).
  4. If no voltage is present, check the wiring harness for supply voltage (5.0v) and ground (0.3v or less), by referring to your corresponding wiring guide. If supply voltage and ground are present, but no output voltage from TP, replace the TP sensor. If supply voltage and ground do not meet specifications, make necessary repairs to the harness or PCM.

Ford F-150/F-250: How to Replace Throttle Position Sensor

A TPS is the throttle position sensor that gives information to the computer of your F-150 or Super Duty on the position of a car's throttle. Your TPS is responsible for checking your engine to ensure fuel efficiency. If you notice your engine light is on, there are difficulties when you change gears, the gas level drops when the tank is full, your car automatically jerks when driving, the engine suddenly stalls, or you feel a surge in speed when on the highway, these are all signs that your TPS needs to be replaced.


  • Paper towel
  • Flat head screw driver
  • Carb cleaner
  • New throttle position sensor

Step 1 - Remove the obstacles

Remove the throttle body cover, then remove throttle body sensor, which is mounted on the front of your mantle fold. Then, take the accelerator cable off using a flat head screw driver by pressing under the part.
  • Figure 1. Throttle Body Cover.
  • Figure 2. Throttle Body Sensor.
  • Figure 3. Accelerator Cable.

Step 2 - Remove the vacuum hose

Figure 4. Remove vacuum hose.
Remove the vacuum hose fitting to access the sensor.

Step 3 - Remove the TPS sensor

  • Figure 5. TPS.
  • Figure 6. TPS.
Make sure to remove the TPS sensor and 2 screws that connect to bottom of throttle body. Once the old sensor is off, replace it with the new one. Clean the throttle body really well, then install it back by reversing the steps above.

Pro Tip

  • When taking off the accelerator cable with the screw driver, remove it softly to avoid breaking the clips.
  • As a fourth step, you may want to clean the electric part of the valve with carb cleaner.
  • Remember to clear the memory of your codes after replacing the TPS.

Testing and troubleshooting the throttle position sensor (TPS) on your Ford or Lincoln car, pick up or SUV is an easy thing to do. You don't even need a scan tool to test it. A simple multimeter will suffice and in this article I'll take you thru' the whole diagnostic process step by step.
Below you'll find a list of Ford and Mercury and Lincoln cars, pick ups and SUV this article applies to (although the tests could apply to any Ford vehicle on the road today). Also in this section you'll find the info to make your testing as easy and as uncomplicated as possible.
OK, one last thing before we jump into the article, you can find a complete list of 4.6L and 5.4L ‘How To Test’ articles that are located in this Web Site and at and this list is found here: Ford 4.6L, 5.4L Index of Articles.

Symptoms of a BAD Ford TPS

The most common symptom is the CHECK ENGINE LIGHT (CEL) is on (also known as the MIL=Malfunction Indicator Light) on your instrument cluster and annoying the heck out of you as you drive. Among other things, your vehicle might be experiencing:
  1. TPS diagnostic trouble codes (DTCs) stored in the vehicle's computer's memory.
    1. P0121: Throttle Position (TP) Circuit Performance Problem.
    2. P0122: Throttle Position (TP) Circuit Low Input.
    3. P0123: Throttle Position (TP) Circuit High Input.
  2. Really BAD gas mileage.
  3. Transmission does not shift out of second gear.
  4. No power as you accelerate the vehicle.
  5. Hesitation when you step on the accelerator pedal.

What tools do I need?

As mentioned at the opening of this article... all that you'll need to be able to use the info and perform the tests in this article is a multimeter (don't have a digital multimeter? Need to buy one? Click here to see my recommendations: Buying a Digital Multimeter for Automotive Diagnostic Testing).
You may need a helper to perform some of these tests.

Circuit Descriptions of the Ford TPS

  • How to Test the 4.6L, 5.4L Ford Throttle Position Sensor (TPS)
  • How to Test the 4.6L, 5.4L Ford Throttle Position Sensor (TPS)
As you already may know, the throttle position sensor (TPS) on your Ford (or Mercury or Lincoln) vehicle has three wires coming out of its connector. Below are short descriptions of the signal each one carries. This are the Circuit Descriptions that we'll be using thru' out the rest of the article to test the TPS on your vehicle.
  1. Circuit labeled 1:
    1. 5 Volts from PCM.
  2. Circuit labeled 2:
    1. Throttle Position (TP) Signal Circuit.
  3. Circuit labeled 3:
    1. Sensor Return (Ground) Circuit.
I recommend that when you test for the particular signal in the wire, that you use a tool to pierce the Wire... such as a Wire-Piercing Probe (click here so that you can see what one looks like: Wire Piercing Probe). Disconnecting and probing the front of the female terminal of the connector can get you into a lot of trouble... if you open up the terminal with the probe you're using.
One last observation... these three circuits go directly to the PCM. So you need to be careful not to short these wires to Power (12 Volts) or you may fry the PCM.

How Does the Ford TPS Work?

Here's some very basic working theory that'll help you to understand the ‘why’ and ‘how’ of the three tests you're gonna' do with the help of this article. OK, in a nutshell.. when you crank and start your Ford vehicle:
  1. The PCM (Powertrain Control Module=Fuel Injection Computer) feeds the throttle position sensor with 5 Volts and a Ground.
  2. This Ground is known as the Sensor Return in Ford tech speak.
  3. As you step on the Accelerator Pedal, the TP sensor translates the amount of throttle plate opening (caused by the accelerator cable) into a voltage signal the PCM can use.
  4. The PCM uses this voltage signal , that will vary with the amount the throttle opens as you accelerate or decelerate the vehicle, to inject fuel, control ignition timing, and the rest of the song and dance the Computer has to do to get your vehicle moving or slowing down.
Pretty simple stuff, no? Well testing it is just as simple. Since you'll be working in the engine compartment, no need to tell you (but I'm gonna' tell you anyway) to be alert and be very careful. Use common sense and take all necessary safety precautions. OK, on with the show... go to TEST 1

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