How To Test The TPS (1991 5.2L, 5.9L V8 Dodge Ram Pickup)

TEST 2: Making Sure The TPS Is Receiving 5 Volts

If the TPS voltage signal stayed stuck during TEST 1, there's a good chance it's not getting any power.

In this next test, we're gonna check if the violet with white stripe (VIO/WHT) wire on the TPS connector is supplying between 4.5 and 5 Volts DC.

The VIO/WHT wire runs to terminal number 1 on the sensor's 3-wire connector (see the diagram above).

To confirm that this wire is delivering the voltage, we'll do a quick multimeter test right at the connector.

Here's how to run the test:

1. 1

   Set your multimeter to Volts DC mode.

2. 2

   Connect the black lead to the battery's negative (-) terminal.

3. 3

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

4. 4

   Unplug the TPS from its connector.

5. 5

   Use the red lead to gently probe terminal 1 on the TPS connector.
   
   Make sure the VIO/WHT wire lines up with terminal number 1.
   
   NOTE: Be careful —don't damage the terminal inside the connector.

6. 6

   Your multimeter should read between 4.5 and 5 Volts DC.

Here's what the results tell you:

CASE 1: You're seeing 4.5 to 5 Volts. That means the TPS is getting power —exactly what we want.

Next, we'll check if it's getting Ground. Go to: TEST 3: Making Sure The TPS Is Receiving Ground.

CASE 2: You're NOT getting 4.5 to 5 Volts. Without power, the TPS won't send out its changing voltage signal.

Here's what usually causes the missing voltage:

• A break or open in the wiring between the TPS connector and the fuel injection computer's connector.
• Sometimes, it's an internal issue inside the computer —but that's rare.

Tracking down this missing voltage goes beyond what we're covering here —but now you know the sensor itself isn't the problem. Your next move is to fix the power issue that's keeping the voltage from reaching the TPS.

TEST 3: Making Sure The TPS Is Receiving Ground

So far, your TPS multimeter tests have confirmed the following:

• TEST 1: The TPS voltage signal doesn't change when you move the throttle plate.
• TEST 2: The sensor is getting power.

In this final test, we're gonna check that the black wire with a light blue stripe (BLK/LT BLU) is delivering Ground to the TPS.

The BLK/LT BLU wire connects to terminal number 3 on the TPS connector (see the illustration above).

We'll use a multimeter to confirm this wire is supplying Ground properly.

NOTE: The Ground comes from the fuel injection computer. Don't connect this wire directly to 12 Volts —doing that will fry the computer. The voltage test below is safe and won't cause any damage.

Follow these steps:

1. 1

   Set your multimeter to Volts DC mode.

2. 2

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

3. 3

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

4. 4

   Unplug the TPS from the connector.

5. 5

   With the black test lead, gently probe terminal 3 on the connector.
   
   Make sure the BLK/LT BLU wire connects to terminal 3.
   
   NOTE: Be careful not to damage the terminal when probing it.

6. 6

   If Ground is present, your multimeter will show 10 to 12 Volts DC.

Here's how to read your results:

CASE 1: You've got Ground (10 to 12 Volts showed up). That's the result you want.

If you confirmed all of the following:

• The TPS voltage doesn't change with throttle movement (TEST 1).
• The sensor is getting 4.5 to 5 Volts (TEST 2).
• And now, the sensor is getting Ground (this test).

Then the TPS is bad and needs to be replaced. Where To Buy The TPS And Save.

CASE 2: You're NOT getting Ground. Double-check your connections and make sure you're testing the right terminal.

If there's still no 10 to 12 Volts, the TPS itself is fine. It's not producing a voltage signal because it's missing Ground.

Figuring out why there's no Ground goes beyond this tutorial, but now you know the sensor isn't the problem. Your next step is to fix the issue that's keeping Ground from reaching it.

The most common causes include:

• A break (open-circuit problem) in the wiring between the TPS connector and the fuel injection computer's connector.
• Less commonly, an internal problem inside the computer itself.

More 5.2L, 5.9L V8 Dodge Ram Pickup Tutorials

You can find a complete list of 5.2L, 5.9L V8 Dodge Ram pickup tutorials in this index:

• 5.2L, 5.9L V8 Dodge Ram Pickup Index Of Articles.

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

• How To Test The Engine Compression (1989-2003 5.2L, 5.9L V8 Dodge Ram Pickup).
• How To Test For A Blown Head Gasket (1989-2003 5.2L, 5.9L V8 Dodge Ram Pickup).
• How To Test The Fuel Pump (1992-2003 5.2L, 5.9L V8 Dodge Ram Pickup).
• How To Test The TPS (1989-1990 5.2L, 5.9L V8 Dodge Ram Pickup.