The throttle position sensor (TPS) and/or diagnostic trouble codes (DTCs) P0121, P0122, P0123 can be tested with only a multimeter and this tutorial will show you how.
With the step-by-step testing instructions, you'll be able to say, 'Yes, the throttle position sensor (TPS) is fried', or 'No, the throttle position sensor (TPS) is good'.
Contents of this tutorial:
You can find this tutorial in Spanish here: Cómo Probar El Sensor TPS (2.0L Breeze, Cirrus, Neon) (at: autotecnico-online.com).
APPLIES TO: This TPS test tutorial applies to the following vehicles (since they use the exact same TPS):
- Chrysler Sebring 2.0L (DOHC): 1995, 1996, 1997, 1998, 1999.
- Dodge Avenger 2.0L (DOHC): 1995, 1996, 1997, 1998, 1999.
- Dodge Neon 2.0L (SOHC): 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002.
- Eagle Talon 2.0L (DOHC): 1995, 1996, 1997, 1998.
- Mitsubishi Eclipse 2.0L (DOHC): 1995, 1996, 1997, 1998, 1999.
- Plymouth Breeze 2.0L (SOHC): 1995, 1996, 1997, 1998, 1999, 2000.
- Plymouth Neon 2.0L (SOHC): 1995, 1996, 1997, 1998, 1999, 2000, 2001.
You can find all of the 2.0L and 2.4L Chrysler 'how to test' tutorials at: Chrysler 2.0L And 2.4L Index Of Articles.
Symptoms Of A Bad TPS
You'll have the check engine light (CEL) illuminated on your instrument cluster and one of several of the following symptoms:
- TPS diagnostic trouble codes (DTCs) stored in the vehicle's computer's memory.
- Really bad gas mileage. You know that it's not the price of gasoline that has you thinking that your car is costing you more at the pump.
- Transmission does not shift out of second gear. Now, this doesn't happen very often, but it happens.
- No power and/or hesitation as you accelerate the vehicle. It feels like all of a sudden someone cut the power out momentarily as you step on the gas to get the vehicle moving.
How The Throttle Position Sensor Works
The throttle position sensor's job is to measure the angle of the throttle plate. So here, in a nutshell, is how the throttle position sensor works when you crank and start your 2.0L (SOHC & DOHC) vehicle:
- The fuel injection computer supplies 5 Volts and Ground to the throttle position sensor.
- Now, since the throttle is closed, the TPS (with power and Ground supplied) sends the PCM (Powertrain Control Module=Fuel Injection Computer) a DC voltage signal of about 0.4 to 0.7 Volts. This value is what the PCM associates with a closed throttle.
- Once you throw the car in drive and accelerate the car, the throttle opens and the throttle position sensor immediately sends this change of the throttle plate angle as an INCREASING voltage signal to the PCM.
- With this increasing voltage signal, the PCM knows it's time to inject more fuel, advance ignition timing, and a host of other things it has to do to keep your 2.0L (SOHC & DOHC) vehicle running optimally.
- As you let go off the accelerator pedal to slow down, the throttle plate closes and of course the TP sensor sends the info to the PCM as it returns to its base voltage signal, till the whole cycle begins again.
Pretty easy stuff? The cool thing is that the tests to check out the TP sensor's performance are as easy too. Now, since you'll be working in the engine compartment take all necessary safety precautions and use common sense. OK, enough of my yakking, let's get this show on the road go to: TPS TEST 1: Testing The TPS Signal.
TPS Circuit Descriptions
The throttle position sensor is a 3-wire sensor that needs 5 Volts and Ground to create its position signal. The following tables will help you identify the color of the wires of your particular vehicle:
| 2.0L DOHC Avenger, Talon, Sebring 1995-1999 | ||
|---|---|---|
| Pin | Wire Color | Description |
| 1 | Black with dark green stripe (BLK/DK GRN) | Ground |
| 2 | Brown with red stripe (BRN/RED) | TPS Signal |
| 3 | Dark green with yellow stripe (DK GRN/YEL) | Power (5 Volts DC) |
| 2.0L SOHC Neon And Breeze | ||
|---|---|---|
| Pin | Wire Color | Description |
| 1 | Black with light blue stripe (BLK/LT BLU) | Ground |
| 2 | Orange with dark blue stripe (ORG/DK BLU) | TPS Signal |
| 3 | Violet with white stripe (VIO/WHT) | Power (5 Volts DC) |
NOTE: The above Breeze and Neon table applies only to the following models:
- Dodge Neon 2.0L (SOHC): 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002.
- Plymouth Breeze 2.0L (SOHC): 1995, 1996, 1997, 1998, 1999, 2000.
- Plymouth Neon 2.0L (SOHC): 1995, 1996, 1997, 1998, 1999, 2000, 2001.
Where To Buy The TPS Sensor And Save
The following links will help you to comparison shop and hopefully save you a few bucks on its purchase:
TPS TEST 1: Testing The TPS Signal
The very first thing that you'll do is verify that the throttle position sensor is creating a good throttle position signal that the PCM on your 2.0L (SOHC, DOHC) can use.
On the Dodge Neon, Plymouth Neon and Breeze, the wire that carries the TP signal to the fuel injection computer is the orange with dark blue stripe (ORG/DK BLU) wire.
On the 1995-1999 2.0L DOHC Avenger, Talon, and Sebring, the wire that carries the TP signal to the fuel injection computer is the brown with red stripe (BRN/RED) wire.
In all of these vehicles, the ORG/DK BLU or BRN/RED wire connect to the female terminal labeled with the number 2 in the image above.
NOTE: The throttle position sensor must remain connected to its electrical connector to be able to test its TP signal. You'll need to use a back probe or a wire piercing probe on the signal wire. You can see an example of this tool here: Wire Piercing Probe.
These are the test steps:
Part 1
- 1
The throttle position sensor must be at normal engine operating temperature, so if the engine is cold, start it up and let it run for a few minutes.
If you car doesn't start, then don't worry about the TPS being at normal engine operating temperature. - 2
Select Volts DC Mode on your multimeter and with the Key On but the engine off, probe the middle wire of the throttle position sensor with the red multimeter test lead.
The throttle position sensor must remain connected to its connector for for this test. - 3
Ground the black multimeter test lead on the battery negative (-) terminal and if you haven't done so already, turn the Key On but don't start the engine.
- 4
The multimeter should register 0.4 to 0.6 Volts DC. If it doesn't, it's nothing to worry about just yet, continue with the next steps.
Part 2
- 5
Now, as you watch the readings on the multimeter, slowly rotate the throttle plate manually.
For a more accurate test result, don't open and close the throttle by stepping on the accelerator pedal, instead, manually do it from the throttle body. - 6
As the throttle opens, the reading on the multimeter, should increase smoothly and without any gaps or skips. Once the throttle opens to its maximum open position, you should see about 4.5 Volts DC on the multimeter's display.
- 7
Now, slowly close the throttle. As it closes, your multimeter's voltage reading should decrease smoothly and without any gaps or skips, to the exact same voltage you noticed in step 4.
Part 3
- 8
OK, now you're gonna' open and close the throttle as before, but with someone lightly tapping on the throttle position sensor with the handle of a screw-driver.
The tapping (with a screw-driver on the TPS) serves to further confirm that the throttle position sensor is good or bad. - 9
Repeat step 8 several times to make sure of your multimeter test results.
Let's examine your TPS signal test result:
CASE 1: The multimeter registered a smooth increase or decrease in voltage with no gaps. This is the correct test result and tells you that the throttle position sensor (TPS) is OK and not malfunctioning. You do not need to do the other 2 tests in this tutorial.
Now, if the throttle position sensor code won't go away, take a look at the info found at: 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 and/or you saw the voltage reading skip or go dead when tapping the TPS. This means that the TPS is bad and needs to be replaced.
CASE 3: The multimeter DID NOT register any voltage. This is not good, but doesn't condemn the TPS as bad yet.
The TPS may be missing either 5 Volts or Ground and you can test these also, go to: TPS TEST 2: Making Sure The TPS Is Getting Power.
