How To Test The TPS (1996-1999 2.5L OHV Dodge Dakota)

TEST 2: Making Sure The TPS Has Power And Ground

If your test result, from TEST 1, indicates that TPS is not producing an increasing voltage signal (as you opened the throttle plate), then there's a good chance that it's missing power or Ground.

So in this test section we're gonna' check that the violet with white stripe (VIO/WHT) wire is feeding the TPS with power and that the black with light blue stripe (BLK/LT BLU) wire is feeding it with Ground.

Testing for power and Ground can easily be done by doing a simple multimeter voltage test. And that's exactly what we're going to do in this test section.

IMPORTANT: The fuel injection computer on your 2.5L OHV Dodge Dakota is the component that provides Ground to the throttle position sensor. So for this reason, you need to be careful not to short-circuit the Ground wire to battery voltage or you'll fry the computer. The multimeter voltage test indicated in the test instructions is a safe way of testing this circuit.

Let's get started:

1. 1

   Check the VIO/WHT wire for power with the Key On Engine Off (KOEO) (see illustration above).
   
   Back probe the VIO/WHT wire with the red multimeter test lead and connect the black lead to the battery negative (-) post.
   
   The multimeter should register 4.5 to 5 Volts DC.

2. 2

   Check the BLK/LT BLU wire for Ground with the Key On Engine Off (KOEO) (see illustration above).
   
   Back probe the BLK/LT BLU wire with the black multimeter test lead and connect the red lead to the battery positive (+) post.
   
   The multimeter should register battery voltage (12+ Volts).

CASE 1: Both Ground and power (5 Volts) are present. This is the correct and expected test result.

Taking into account that the TP sensor did not produce the expected voltage increase in TEST 1 and that it's getting power and Ground, you can now conclude that the TPS is bad and needs to be replaced.

CASE 2: Either Ground or power ARE NOT present. Without power or Ground the throttle position sensor will not produce a throttle angle voltage signal.

Although it's beyond the scope of this tutorial to further diagnose this wiring problem, your next step is to check the continuity of the power and Ground circuits between the TPS and the fuel injection computer.