How To Test The Throttle Position Sensor (2001-2007 3.0L Ford Escape)

The throttle position sensor (TPS) on your 3.0L V6 Ford Escape and Mazda Tribute can be easily tested with a multimeter.

Although a scan tool is a "must" tool to have, no scan tool is required to troubleshoot and diagnose the TPS and I'll show you how to do it step by step.

I've also included some important do's and don'ts to make your diagnostic as easy and as uncomplicated as possible.

You can find this tutorial in Spanish here: Cómo Probar El Sensor TPS Con Multímetro (2001-2007 3.0L Ford Escape) (at: autotecnico-online.com).

APPLIES TO: This tutorial applies to the following vehicles:

• 3.0L Ford Escape: 2001, 2002, 2003, 2004, 2005, 2006, 2007
• 3.0L Mazda Tribute: 2001, 2002, 2003, 2004, 2005, 2006, 2007

Symptoms Of A Bad Escape (Tribute) TPS

Beside the check engine light (CEL) being on and driving you nuts, here are some other symptoms your Ford Escape or Mazda Tribute may be experiencing:

1. TPS diagnostic trouble codes (DTCs) stored in the vehicle's computer's memory.
   • P0121: Throttle Position (TP) Circuit Performance Problem.
   • P0122: Throttle Position (TP) Circuit Low Input.
   • 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?

To test the throttle position sensor you don't need any expensive testing equipment or tools, just a simple multimeter will do to be able to use the info in this article (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 Escape (Tribute) TPS

There are three wires sticking out of the Ford Escape (and Mazda Tribute) throttle position sensor (TPS). Each wire provides a specific type of signal to the TPS or to the PCM (Powertrain Control Module=Fuel Injection Computer). Below are the circuit descriptions of each.

• Circuit labeled 1:
  • Sensor Return (Ground) Circuit.
• Circuit labeled 2:
  • Throttle Position (TP) Signal Circuit.
• Circuit labeled 3:
  • 5 Volts from PCM.

I'm gonna' make one very important recommendation to you when testing the signals of each wire. And that is to avoid probing the front of the female terminal of the TPS connector with the multimeter test leads. It's best to use a back probe or a wire-piercing probe (you can see what one looks like here: Wire Piercing Probe) to get to and test the signal.

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 Escape (Mazda Tribute) 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 throttle position sensor gets 5 Volts and Ground from the PCM.
2. Once the car starts and is idling, the TPS sends a base throttle position signal of about 0.9 to 1 Volt to the PCM.
3. Once you step on the accelerator pedal to start moving the car, the TP sensor starts to measure the amount of throttle plate opening (caused by your foot) into a rising voltage signal the PCM uses to calculate fuel injection, ignition timing, transmission shift points, etc.
4. As you let go off the gas pedal (accelerator pedal), the TP sensor decreases the voltage signal to the PCM and returns to its base voltage signal, till you step on the accelerator pedal to move the vehicle and the cycle begins again.

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, let's get this show on the road! Go to: TEST 1: Making Sure The TPS Is Getting 5 Volts.

Where To Buy The TPS And Save

The following links will help you comparison shop for the throttle position sensor. If the locking tab, on the TPS connector has broken, you can buy it online too. I have included a link where you can buy it below: