Testing the throttle position sensor (TPS) on your 2.0L 4 cylinder equipped Ford Escape is easy and can be done with a simple multimeter.
In this tutorial, I'll show you how to do it in a step-by-step way and more importantly, I'll show you how to interpret your TPS test results.
Contents of this tutorial:
- Symptoms Of A Bad Throttle Position Sensor.
- TEST 1: Testing The Throttle Position Sensor Voltage Signal.
- TEST 2: Verifying Throttle Position Sensor Has Power.
- TEST 3: Verifying Throttle Position Sensor Has Ground.
- Where To Buy Your Throttle Position Sensor And Save.
- More 2.0L Ford Diagnostic Tutorials.
You can find this tutorial in Spanish here: Cómo Probar el Sensor TPS (2.0L Ford Escape) (at: autotecnico-online.com).
Symptoms Of A Bad Throttle Position Sensor
A failed throttle position sensor (TPS) will light up the check engine light (CEL) on your 2.0L Ford Escape.
You'll also see one or more of the following symptoms:
- A TPS diagnostic trouble code (DTC) stored in the PCM's memory:
- P0121: Throttle Position (TP) Circuit Performance Problem.
- P0122: Throttle Position (TP) Circuit Low Input.
- P0123: Throttle Position (TP) Circuit High Input.
- Your 2.0L Ford Escape fails the smog check (state mandated emissions test).
- Bad gas mileage.
- Hard start and/or extended cranking time (after shut off).
- Black smoke coming out of the tailpipe.
- Hesitation when accelerating your vehicle down the road.
Thankfully, the TPS can be tested without a scan tool and in the next section we'll start with the very first test.
TEST 1: Testing The Throttle Position Sensor Voltage Signal
As you're already aware, the throttle position sensor's is tasked with reporting the throttle plate angle to the fuel injection computer as you step on and off the accelerator pedal.
Like any other electrical component on your 2.0L Escape, the TPS needs power and ground to create a throttle angle voltage signal. The throttle angle voltage signal it creates is sent to the fuel injection computer thru' the wire that connects to the TPS terminal labeled with the letter B in the illustration above.
So the first thing we'll do, to see if the TPS is OK or not, is to tap into this wire with a multimeter and verify the TPS is creating a correct throttle angle voltage signal (as we manually open and close the throttle plate).
NOTE: The throttle position sensor has to remain connected to its connector for this test to work (this is where a wire piercing probe comes in handy to get to the signal inside the wire. To see what one looks like, click here: Wire Piercing Probe Tool.)
OK, let's start:
Place your multimeter in Volts DC mode and with the red multimeter test lead probe the middle wire of the sensor's connector. This is the wire that connects to TPS connector terminal letter B in the illustration above.
Ground the black multimeter test lead on the battery negative terminal. Have your helper turn the Key On, but don't start the engine (this will power up the TP sensor).
Your multimeter should report a voltage between .2 to 0.9 Volts DC. If your multimeter doesn't, don't worry about it just yet, continue with the other steps.
Now, slowly open the throttle (by hand and from the engine compartment) while you observe the change in voltage numbers on your multimeter.
For this test result to be accurate, you need to open the throttle by hand and not from inside the vehicle.
As the throttle opens, the voltage numbers will increase. This increase in voltage should be smooth and without any gaps or skips. Once the throttle is wide open, your multimeter should read somewhere between 3.5 to 4.5 Volts DC.
Now, slowly close the throttle. As the throttle is closing, you should see the voltage decrease smoothly and without any gaps or skips, to the exact same voltage you noticed in step 4.
OK, now you'll need someone to help you lightly tap on the throttle position sensor with the handle of a screw-driver (or something similar, and I want to emphasize the words ‘lightly tap’) as you slowly open and close the throttle and observe the multimeter.
If the TPS is bad, the tapping will cause the voltage numbers to skip or go blank. If the TPS is OK, the tapping will have no effect on the voltage numbers.
Repeat step 7 several times to make sure of your multimeter test results.
Let's take a look at your test results:
CASE 1: The throttle angle voltage increased and decreased as you opened and closed the throttle plate. This confirms that your 2.0L Ford Escape's TP sensor is OK and not defective.
CASE 2: The throttle angle voltage DID NOT increase (and/or decrease) as you opened and closed the throttle plate. This tells you that the TPS is bad and causing the TPS trouble code lighting up the check engine light (CEL) on your 2.0L Ford Escape.
Before you run out and buy it, I'm gonna' suggest that you do two more tests. One is to check that the TPS is getting power. The other is to check that it's ground. To check that the TPS is getting power, go to: TEST 2: Verifying Throttle Position Sensor Has Power.
CASE 3: Multimeter DID NOT register any voltage, this test result doesn't condemn the TP sensor as BAD just yet. Why? Because...
, the TP sensor may be missing either power or ground. So the next step is to check that the TP sensor is getting power, go to: TEST 2: Verifying Throttle Position Sensor Has Power.