How To Test The TPS (1991-1995 2.5L Caravan And Voyager)

TEST 2: Making Sure The TPS Is Getting 5 Volts

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

In the photo above, I've labeled the VIO/WHT wire with the number 1.

We can easily check for the presence of these 5 Volts in the VIO/WHT wire by doing 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.

Let's get testing:

1. 1

   Place your multimeter in Volts DC mode.

2. 2

   Disconnect the TPS from its electrical connector.

3. 3

   With the red multimeter test lead (and an appropriate tool) probe the wire labeled with the number 1 in the photo above.

4. 4

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

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: 4.5 to 5 Volts are present in the VIO/WHT wire. This is the correct test result and confirms that the throttle position sensor is getting the power it needs to function.

The next step is to verify the presence of Ground in the black with light blue stripe (BLK/LT BLU) wire, go to: TEST 3: Making Sure The TPS Is Getting Ground.

CASE 2: 4.5 to 5 Volts ARE NOT present in the VIO/WHT wire. This test result confirms that the TPS is not getting power.

The most likely reasons for this are:

• The VIO/WHT wire has open-circuit problem.
• 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 2.5L Dodge Caravan or 2.5L Plymouth Voyager, as bad.

TEST 3: Making Sure The TPS Is Getting Ground

Your throttle position sensor test results have, up to this point, confirmed that:

• The TPS signal voltage does not increase/decrease when you open/close the throttle plate.
• The throttle position sensor is getting 5 Volts DC on the VIO/WHT wire of its electrical connector.

The last test we'll do is confirm that Ground is being supplied to the TPS sensor.

The wire that we're gonna' test, for the presence of Ground, is the black with light blue stripe (BLK/LT BLU) wire of the connector.

In the photo above, this wire is 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 power (12 Volts) to this wire or you'll fry the fuel injection computer.

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

   With the black multimeter test lead (and an appropriate tool) probe the wire labeled with the number 3 in the photo above.

4. 4

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

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 showed 10 to 12 Volts. This is the correct test result and tells you that the TPS is getting Ground.

The TPS sensor is bad and needs to be replaced only if you have:

1. Confirmed that the TPS signal voltage does not increase/decrease when you open/close the throttle plate (TEST 1).
2. Confirmed that the TP sensor is getting 5 Volts (TEST 2).
3. In this test section, you have confirmed that the TP sensor is receiving Ground.

If you'd like to save some bucks on the TP sensor, consult my recommendations here: Where To Buy The TPS And Save.

CASE 2: The multimeter DID NOT show 10 to 12 Volts. This test result confirms that the BLK/LT BLU wire 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.
• 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 2.5L Dodge Caravan or 2.5L Plymouth Voyager, as bad.

The TPS Code Won't Go Away

In some cases, the TPS diagnostic trouble code keeps coming back even after you have replace the sensor or you have confirmed that it's functioning correctly.

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 (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.

More 2.5L Dodge Caravan And Plymouth Voyager Tutorials

You can find all of the 2.5L Dodge Caravan and 2.5L Plymouth Voyager tutorials in this index:

• Chrysler 2.5L Index Of Articles.

Here's a small sample of the articles/tutorials you'll find in the index:

• How To Test A Blown Head Gasket (1991-1995 2.5L Caravan And Voyager).
• How To Test Engine Compression (1991-1995 2.5L Caravan And Voyager).
• Ignition System Wiring Diagram (1994-1995 2.5L Caravan And Voyager).
• How To Test The MAP Sensor (1991-1995 2.5L Caravan, Voyager).