How To Test The TPS (1989-1990 5.2L, 5.9L V8 Dodge Ram Pickup)

TEST 2: Making Sure The TPS Is Getting 5 Volts

Your TEST 1 result shows:

• The TPS voltage stays stuck at one value when you fully open the throttle plate.

Now we're gonna check if the throttle position sensor (TPS) is getting power through the violet (VIO) or violet with white stripe (VIO/WHT) wire on the TPS 3-wire connector.

Once we confirm it's getting the proper 5 Volts, we'll move on to TEST 3 and check for Ground.

NOTE: Be extra careful when testing the front of the connector terminals —damaging them means you'll need to replace the connector.

Here's what to do next:

1. 1

   Switch your multimeter to its DC voltage setting.

2. 2

   Unplug the TPS from the 3-wire connector.

3. 3

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

4. 4

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

5. 5

   Carefully probe terminal number 1 with the red multimeter lead.
   
   You're testing the terminal on the TPS connector —not the sensor.
   
   NOTE: Make sure that this terminal corresponds to the VIO or VIO/WHT wire of the connector.

6. 6

   You should get a reading between 4.5 and 5 Volts DC.

Here's how to read your results:

CASE 1: You're getting 4.5 to 5 Volts. That's exactly what we want and need to see.

Next, we'll make sure the BLK/LT BLU wire is supplying Ground to the TPS. Go to: TEST 3: Making Sure The TPS Is Getting Ground.

CASE 2: No voltage is present. If the sensor isn't getting 4.5 to 5 Volts, it won't produce a TPS signal.

Tracking down this missing voltage isn't covered in this tutorial, but your next step is to figure out why that power's missing and get it restored.

The most common cause is a break (open-circuit problem) in the wire between the TPS connector. In very rare cases, the fuel injection computer has an internal problem.

TEST 3: Making Sure The TPS Is Getting Ground

At this point, your TPS tests have confirmed the following:

• TEST 1: The TPS signal voltage stays stuck, no matter how you move the throttle plate.
• TEST 2: The sensor is definitely getting power from the fuel injection computer.

Now it's time for one last check —we're gonna see if the black with light blue stripe (BLK/LT BLU) wire is supplying Ground to the TPS.

CAUTION: Don't connect this wire to 12 Volts from the battery. Doing that will damage your Dodge Ram pickup's fuel injection computer. The voltage test I'm outlining below is a safe way to check for the presence of Ground in the circuit.

Let's get started:

1. 1

   Set your multimeter to Volts DC mode.

2. 2

   Unplug the TPS from the 3-wire connector.

3. 3

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

4. 4

   Turn the ignition key to the ON position. Don't start the engine.

5. 5

   With the black test lead, gently probe terminal 3 on the connector.
   
   NOTE: Double-check that the BLK/LT BLU wire corresponds to this terminal.

6. 6

   Your multimeter should show somewhere between 10 and 12 Volts DC.

Here's what the results are telling us:

CASE 1: The BLK/LT BLU wire is supplying Ground. That's what you want to see.

If you've confirmed all of this:

1. The TPS signal doesn't change with throttle movement (TEST 1).
2. The TPS has power (TEST 2).
3. This test shows it's got Ground.

Then there's no doubt that the TPS is dead and needs to be replaced.

Want to save some cash? Check out my TP sensor recommendations: Where To Buy The TPS And Save.

CASE 2: The BLK/LT BLU wire isn't providing Ground. Without that Ground, the TPS can't do its job.

Tracking down a missing Ground is outside the scope of this tutorial, but your next move is to find the break and fix it.

The usual suspect? An open-circuit somewhere between the TPS connector and the computer's connector. In some rare cases, the fuel injection computer has suffered an internal fault.

More 5.2L, 5.9L V8 Dodge Ram Pickup Tutorials

I've written quite a few 5.2L, 5.9L V8 Dodge Ram pickup 'how to test' tutorials. You can find them in this index:

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

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

• How To Test The TPS (1989-1990 5.2L, 5.9L V8 Dodge Ram Pickup).
• How To Test The Camshaft Position Sensor (1992-1995 5.2L, 5.9L Dodge Ram Pickup).
• Troubleshooting A Blown Head Gasket (1989-2003 5.2L, 5.9L V8 Dodge Ram Pickup).
• How To Test Engine Compression (1989-2003 5.2L, 5.9L V8 Dodge Ram Pickup).