How To Test The TP Sensor (1998-2000 3.0L Chrysler)

This tutorial will help you test the throttle position sensor on your 1998-2000 Dodge (or Plymouth) mini-van equipped with a 3.0L V6 engine.

The TPS test is done with a multimeter (no scan tool required) and while the TPS is still mounted to the throttle body.

The following tutorials may be of help:

• How To Test The Throttle Position Sensor (1991-1995 3.0L Chrysler) (at: troubleshootmyvehicle.com).
• How To Test The Throttle Position Sensor (1996-1997 3.0L Caravan/Voyager).

You can find this tutorial in Spanish here: Cómo Probar El Sensor TPS (1998-2000 3.0L Dodge/Plymouth Mini-Van) (at: autotecnico-online.com).

Symptoms Of A Bad Throttle Position Sensor

Since the TPS plays such a critical role in your mini-van's engine management system, when it fails the PCM will set a diagnostic trouble code (DTC) and will light up the check engine light (CEL).

Here's a more detailed list of symptoms your 1998-2000 3.0L Dodge (or Plymouth) mini-van will experience:

1. 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.
2. Your 1998-2000 3.0L V6 Dodge/Plymouth mini-van fails the smog check (state mandated emissions test).
3. Bad gas mileage.
4. Hard start and/or extended cranking time (after shut off).
5. Black smoke coming out of the tailpipe.
6. Hesitation when accelerating your vehicle down the road.

As I mentioned at the beginning of this tutorial, the TPS can be tested without a scan tool and in the next section we'll start with the very first test.

Where To Buy Your TP Sensor And Save

The following links will help you to comparison shop for the aftermarket and original equipment Mopar throttle position sensor:

Not sure if the above TP sensor fits your particular 1998-2000 3.0L V6 equipped Dodge or Plymouth? Don't worry, once you get to the site, they'll make sure it fits by asking you the particulars of your vehicle. If it doesn't fit, they'll find you the right one.

TEST 1: Testing The Throttle Position Sensor Voltage Signal

In a good throttle position sensor (TPS), the throttle plate angle voltage signal it creates increases as the throttle plate opens and decreases as it closes.

The cool thing is that by tapping into the ORG/DK BLU wire, of the TPS connector with a multimeter, you and I can easily verify this voltage output.

This is exactly what we're gonna' do in this test section to find out if the TPS is bad or not.

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:

1. 1

   Place your multimeter in Volts DC mode and with the red multimeter test lead probe the ORG/DK BLU wire of the sensor's connector.

2. 2

   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).

3. 3

   Your multimeter should report a voltage between 0.2 to 0.9 Volts DC. If your multimeter doesn't, don't worry about it just yet, continue with the other steps.

Part 2

1. 4

   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.

2. 5

   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.

3. 6

   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.

Part 3

1. 7

   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.

2. 8

   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 the TP sensor, on your 1998-2000 3.0L V6 Caravan (Grand Caravan, Voyager, Grand Voyager), 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 1998-2000 3.0L V6 Caravan (Grand Caravan, Voyager, Grand Voyager).

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: The 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.