How To Test The Throttle Position Sensor (TPS) -3.0L Chrysler

The throttle position sensor (TPS) provides one of the most critical pieces of information that your 3.0L Chrysler vehicle's needs to run correctly.

So, when this bad boy fails, your car just won't run right.

Thankfully, testing the throttle position sensor isn't hard and since it simply involves making sure that it's creating a throttle plate angle signal and that it's getting both power and ground. In this tutorial I'll show you how in a step-by-step manner.

You'll also be able to diagnose any of the following TP sensor trouble codes that may be lighting up the check engine light (CEL) on your OBD I 3.0L Chrysler car or mini-van:

  1. Trouble Code 24: TPS Voltage Low.
  2. Trouble Code 24: TPS Voltage High.

Basics Of The Throttle Position Sensor (TPS)

How To Test The Throttle Position Sensor (TPS) -3.0L Chrysler

As you step on, or off, the accelerator, the throttle plate (on the intake manifold's throttle body) opens or closes.

This throttle plate action lets more (or less) air into the engine.

So that the fuel injection computer can inject the correct amount of fuel for the amount of air entering the engine (at any given throttle plate angle)...

...The throttle position sensor's job is to measure the throttle plate opens and closes and then relay this throttle plate angle info to your vehicle's fuel injection computer.

As you're already aware, the throttle position sensor (TPS) has 3 wires coming out of its harness connector and the middle wire is the one that sends the TP signal back to the computer. The other two wires provide power and ground (to the TPS).

In the table below, you'll find a short description of what each wire does:

3.0L Chrysler TPS Circuits
(1991, 1992, 1993, 1994, 1995)
Pin Wire Color Description
1 BLK/LT BLU Sensor Ground
2 ORG/DK BLU (or DK BLU) Throttle Position Signal
3 VIO/WHT (or VIO) 5 Volts

TEST 1: Checking The Throttle Position Sensor (TPS) Signal

How To Test The Throttle Position Sensor (TPS) -3.0L Chrysler

9 times out of 10, when the throttle position sensor fails... it simply stops creating a throttle plate signal.

To explain this a bit further: In a good throttle position sensor, as the throttle plate angle increases... the TP signal's voltage increases and as the throttle angle decreases, the TP signal's voltage decreases.

So, in this first test, we'll tap into the throttle position sensor's middle wire with a multimeter and see if the voltage signal increases when you open up the throttle plate and decreases when you close the throttle plate.

IMPORTANT: This is an on car test of the sensor and the throttle position sensor must remain connected to its harness connector. Also, depending on your specific vehicle, the middle wire of the TPS harness connector will be an ORG/DK BLU wire or a DK BLU wire

Here are the test steps:

  1. 1

    Place your multimeter in Volts DC mode and connect the red test lead to the ORG/DK BLU (or DK BLU) wire of the TP sensor harness connector.

    NOTE: The TP sensor connector needs to be connected to the TPS, so you'll need to either back-probe the connector or use a wire piercing probe to get to the signal inside the wire (to see what a wire piercing probe looks like: Wire Piercing Probe Tool).

  2. 2

    Ground the black multimeter test lead directly on the battery negative (-) post.

    At this point (with the throttle plate closed) your multimeter should read a voltage between 0.3 to 1.0 volt DC.

  3. 3

    Manually rotate the throttle.

    You'll get the best results by opening and closing the throttle directly on the throttle body instead of stepping on the accelerator pedal.

  4. 4

    The multimeter should show an increasing voltage as you (or your helper) open up the throttle.

    With the throttle plate completely open, your multimeter should read: 3.2 to 4.9 Volts DC.

    You'll get the best results by opening and closing the throttle directly on the throttle body instead of stepping on the accelerator pedal.

  5. 5

    The multimeter should show a decreasing voltage as you begin to close the throttle.

  6. 6

    Using a screwdriver's handle, gently tap the TP sensor as you open and close the throttle and observer the multimeter.

    The purpose (of tapping the TP sensor with the screwdriver's handle) is to see if the TP sensor shows gap's in the voltage signal. Why? Because a good TP sensor will show a continuous increasing or decreasing voltage signal even while getting tapped by the screw-driver's handle.

Let's take a look at what your test results mean:

CASE 1: The TP sensor signal's voltage increased and decreased smoothly and without gaps. This tells that the throttle position sensor on your 3.0L Chrysler car (or mini-van) IS NOT defective.

Since the throttle position sensor is creating an increasing/decreasing voltage signal on the ORG/DK BLU wire, this test result also says that:

  1. The TPS is getting power on the VIO/WHT wire of its harness connector.
  2. The TPS is getting ground on the BLK/LT BLU wire of its harness connector.

CASE 2: The TP sensor signal's voltage did not increase or decrease. This test result usually means that the throttle position sensor on your car (or mini-van) is bad and needs to be replaced but to make absolutely sure...

I suggest that you verify that it's getting power and ground. So, to continue with the TPS diagnostic, go to TEST 2: Makign Sure The TPS Is Getting Power.

CASE 3: The TP sensor signal's voltage showed gaps in its voltage output as you tapped the sensor with the screwdriver. If the gaps in the multimeter's voltage readings only showed up when you were tapping on the TPS (with the screwdriver's handle) then this test result tells you that the TPS is bad and needs to be replaced.