How To Test The TPS (1997-2003 5.2L, 5.9L Dodge Ram Pickup/Van)

TPS TEST 2: Making Sure The TPS Is Getting 5 Volts

If you've reached this point, then it means that in TEST 1, the TPS did not produce the correct voltage signal as you manually opened and closed the throttle plate.

In this test, you'll use your multimeter once again to check that the TPS is being fed with power since without power, it won't work.

In case you're wondering, this ‘power’ comes in the form of 5 Volts DC from the fuel injection computer (PCM).

Depending on your specific Dodge Ram pickup or van, the wire labeled with the number 3 (in the photo above) will be a violet with white stripe (VIO/WHT) wire or an orange (ORG) wire.

This test will help you to confirm if these 5 Volts are present or not.

This is what you'll need to do:

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 3 in the photo above.
   
   NOTE: Depending on your particular Dodge pickup or van, this wire will be a VIO/WHT wire or an ORG wire.

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.

OK, now let's interpret your test results below:

CASE 1: The multimeter registered 4.5 to 5 Volts. This is the correct test result and confirms that the fuel injection computer and the circuit is supplying the TPS with power.

The next step is to test the Ground circuit of the throttle position sensor, go to: TPS TEST 3: Making Sure The TPS Is Getting Ground.

CASE 2: The multimeter DID NOT register 4.5 to 5 Volts. Without this voltage the TPS will not produce a TPS signal.

This usually happens when the computer or the wire do NOT providing these 5 Volts. The two most likely reasons for this are: 1) an open-circuit problem in the wire or 2) the PCM may be fried.

Altho' it's beyond the scope of this article to test these two conditions, you have now eliminated the throttle position sensor (TPS) on your 5.2L, 5.9L Dodge as being the cause of the problem and/or the TPS diagnostic trouble code (DTC) lighting up the check engine light (CEL).

TPS TEST 3: Making Sure The TPS Is Getting Ground

So far you have verified several important things:

One: A TPS failure code is lighting up the check engine light (CEL) on your Dodge's instrument cluster.

Two: The TPS is not creating a throttle position voltage signal when you manually open and close the throttle plate (TPS TEST 1).

Three: That the TPS is getting power (TPS TEST 2).

The last test, before condemning the throttle position sensor as defective, is to verify that it also has a good Ground.

IMPORTANT: The PCM is the one that provides this Ground internally, so be careful and don't accidentally or intentionally apply power (12 Volts) to this circuit or you'll fry the PCM. The multimeter voltage test described in the test steps is a safe way of testing 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

   With the black multimeter test lead and an appropriate tool probe the wire labeled with the number 1 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 it lets you conclude that the PCM and the wire/circuit (that supply this Ground) are OK.

This multimeter test result also confirms that the TPS sensor is bad and needs to be replaced, only if you have:

1. Confirmed that you have a TPS failure code lighting up the check engine light.
2. Confirmed that the TP sensor is not creating an increasing/decreasing voltage signal when you open/close the throttle plate (TPS TEST 1).
3. Confirmed that the TP sensor is getting power from the PCM (TPS TEST 2).
4. In this test section, you have confirmed that the TP sensor does have Ground.

Taking all four results above, you can confidently conclude the TP sensor is bad and needs to be replaced. If you'd like to save some bucks on the TP sensor, check out this section: Where To Buy The TPS And Save.

CASE 2: The multimeter DID NOT show 10 to 12 Volts. Then this indicates a problem with either the PCM (internal fault/problem) or an open in the wire between the TPS and the PCM itself.

Altho' testing these two conditions are beyond the scope of this article, you have now eliminated the throttle position sensor (TPS) on your 5.2L, 5.9L Dodge as being the cause of the problem and/or the TPS diagnostic trouble code (DTC) lighting up the check engine light (CEL).

TPS Code Won't Go Away

So you've tested the throttle position sensor (TPS) and according to the test results, the TPS is good, but the check engine light keeps coming back on even after you erased the diagnostic trouble code (DTC) from the computer's (PCM) memory. Well, 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 so that the engine could be idled up and mask a miss/misfire and/or rough idle. This increases the TP sensor's signal to the PCM. The PCM 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 5.2L, 5.9L Dodge Ram Diagnostic Tutorials

I've written quite a few 5.2L, 5.9L Dodge ‘how to test’ tutorials that may help you troubleshoot the issues on your Dodge van or pick up. You can find them in these two indexes:

• 5.2L, 5.9L Dodge Index Of Articles.
• 3.9L, 5.2L, 5.9L Dodge Index Of Articles.

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

• How To Test A No Start Condition (Dodge 3.9L, 5.2L, 5.9L).
• How To Diagnose Misfire Codes (Dodge 3.9L, 5.2L, 5.9L).
• How To Test The Fuel Injectors (Dodge 3.9L, 5.2L, 5.9L).
• How To Test The Ignition Coil -No Start Tests (Chrysler 3.9L, 5.2L, 5.9L).
• How To Test The MAP Sensor (P0107, P0108) (Dodge 3.9L, 5.2L, 5.9L).