How To Test The TPS (1998-2000 2.4L Dodge, Plymouth Mini-Van)

TEST 2: Making Sure The TPS Is Getting 5 Volts

The wire that supplies the throttle position sensor with 5 Volts is the violet with white stripe (VIO/WHT) wire of the sensor's 3-wire connector.

The VIO/WHT wire connects to the terminal labeled with the number 1 in the photo above.

To make sure that these 5 Volts are present in the VIO/WHT wire, we'll do a simple multimeter voltage test.

NOTE: Avoid probing the front of the female terminal with your multimeter test lead. Use a back probe or a wire piercing probe instead. If you do probe the front of the terminal, do it very gently so that it won't get damaged.

Let's get testing:

1. 1

   Place your multimeter in Volts DC mode.

2. 2

   Disconnect the TPS from its electrical connector.

3. 3

   Connect the black multimeter test lead to the negative (-) battery terminal.

4. 4

   With the red multimeter test lead and an appropriate tool probe the VIO/WHT wire of the sensor's 3-wire connector.

5. 5

   Turn the key to its ON position but don't start the engine.

6. 6

   The multimeter should display 4.5 to 5 Volts.

Let's analyze your test result:

CASE 1: The VIO/WHT wire is supplying 4.5 to 5 Volts DC. This is the correct test result and confirms that the throttle position sensor is receiving 5 Volts DC from your mini-van's fuel injection computer.

Now, you need to make sure that Ground is present in the black with light blue stripe (BLK/LT BLU) wire. For this test go to: TEST 3: Making Sure The TPS Is Getting Ground.

CASE 2: The VIO/WHT wire IS NOT supplying 4.5 to 5 Volts DC. Without these 5 Volts, the throttle position sensor will not function.

The most likely reasons for these missing 5 Volts are:

• The VIO/WHT wire has open-circuit problem between the throttle position sensor's 3-wire connector and the fuel injection computer's connector.
• The MAP sensor has an internal short-circuit problem.
• The fuel injection computer may be fried (although a very rare thing to happen).

Altho' it's beyond the scope of this tutorial to test these conditions, you have now eliminated the throttle position sensor (TPS) on your 2.4L Dodge Caravan or 2.4L Plymouth Voyager as bad.

TEST 3: Making Sure The TPS Is Getting Ground

So far, your throttle position sensor diagnostic tests have confirmed that:

• The TPS signal voltage does not increase/decrease when you open/close the throttle plate (TEST 1).
• The throttle position sensor is receiving 5 Volts DC (TEST 2).

In this last test section we're gonna' make sure that the black with light blue stripe (BLK/LT BLU) wire of the connector is providing Ground to the sensor.

In the photo above, this BLK/LT BLU wire connects to the female terminal that's labeled with the number 3.

IMPORTANT: The fuel injection computer is the one that provides this Ground internally, so be careful and don't accidentally or intentionally apply battery power (12 Volts) to this wire or you'll fry the fuel injection computer. The voltage test, that's done with a multimeter and that I'm suggesting below, is a safe way to test for the presence of Ground in the wire.

OK, here are the test steps:

1. 1

   Place your multimeter in Volts DC mode.

2. 2

   Disconnect the TPS from its electrical connector.

3. 3

   Connect the red multimeter test lead to the positive (+) battery terminal.

4. 4

   With the black multimeter test lead and an appropriate tool probe the BLK/LT BLU wire.

5. 5

   Turn the key to its ON position but don't start the engine.

6. 6

   The multimeter should display 10 to 12 Volts.

Let's take a look at your test results:

CASE 1: The multimeter registered 10 to 12 Volts. This is the correct test result and confirms that the BLK/LT BLU wire is supplying Ground to the throttle position sensor.

You can conclude that the throttle position sensor is bad and needs to be replaced only if you have:

• Confirmed that TPS voltage signal does not increase/decrease as the throttle plate opens/closes (TEST 1).
• Confirmed that the VIO/WHT wire is supplying 5 Volts to the TPS sensor (TEST 2).
• Confirmed that Ground is being supplied to the TPS sensor by the BLK/LT BLU wire.

If you'd like to save a few dollars on the purchase of the TP sensor, consult my recommendations here: Where To Buy The TPS And Save.

CASE 2: The multimeter DID NOT register 10 to 12 Volts. This test result confirms that the BLK/LT BLU is not feeding the TPS sensor with Ground. Without Ground the throttle position sensor will not create its TPS signal.

The most likely reasons for this missing Ground are:

• The BLK/LT BLU wire has open-circuit problem between the TPS sensor's connector and the fuel injection computer's connector.
• The fuel injection computer may be fried (although a very rare thing to happen).

Altho' it's beyond the scope of this tutorial to test these conditions, you have now eliminated the throttle position sensor (TPS) on your 2.4L Dodge Caravan or 2.4L Plymouth Voyager as bad.

The TPS Code Won't Go Away

In some cases, although the throttle position sensor is good, the fuel injection computer continues to set a TPS diagnostic trouble code. This causes the check engine light to illuminate after a short test drive.

If this is happening to you, here are a couple of suggestions that might inspire your next diagnostic move:

1. The throttle plate's idle-stop screw's factory adjustment has been altered to rev up the engine (see photo above).
   
   This is usually done to increase the engine's RPM at idle to mask a rough idle problem. This increases the TP sensor's signal to the fuel injection computer. The fuel injection computer doesn't like it and light ups the check engine light (CEL).
2. The throttle cable is binding and causing the throttle plate to not fully close.
   
   This can be verified by simply having someone inside the vehicle pushing the accelerator pedal to the floor and releasing it, with the engine OFF, while you visually check that the throttle plate and cable are not getting stuck somewhere in their travel.
3. The TPS is failing intermittently. Which means that it works fine most of the time, but every now and then it doesn't:
   
   I have found that the best way to test these intermittent problems is to road-test the vehicle with the multimeter hooked up to the TP signal wire with a long wire so that I can comfortably observe the signal going up and down as I or someone else drives.
4. The TP sensor's connector is bad, usually the locking tab is broken and the connector has worked itself loose, causing an intermittent false connection.