How To Test The Throttle Position Sensor (2.5L V6 Grand Vitara)

TEST 2: Verifying Throttle Position Sensor Has Power

The throttle position sensor (TPS), like any automotive electrical component, needs power and Ground to function.

If the TPS is missing either power or Ground, it won't be able to create a throttle angle voltage signal.

So, in this test section we're gonna' check the gray with red stripe (GRY/RED) wire, of the TPS connector, to see if it's feeding the TPS with 5 Volts DC (or not).

OK, let's get testing:

1. 1

   Place your multimeter's dial in Volts DC mode and turn the key on but don't start the engine.
   
   This will power up the TP sensor's connector.

2. 2

   Probe the GRY/RED wire of the TPS connector with the red multimeter test lead.
   
   IMPORTANT Use a back probe or a wire piercing probe instead of probing the front of the TPS electrical connector.

3. 3

   Connect the black multimeter test lead to a good and clean Ground point on the engine or directly on the negative (-) battery terminal.

4. 4

   When you've set up the test, have a helper turn the Key On Engine Off (KOEO).

5. 5

   Your multimeter should display 4.5 to 5 Volts on its screen if the GRY/RED wire has power.

Let's take a look at your test results:

CASE 1: The GRY/RED wire, of the TPS connector, has 4.5 to 5 Volts. So far so good since this tells you that the throttle position sensor (TPS) is getting power from the fuel injection computer.

The next and last test, is to make sure that the throttle position sensor is getting Ground (from the PCM too). For this test, go to: TEST 3: Verifying Throttle Position Sensor Has Ground.

CASE 2: The GRY/RED wire, of the TPS connector, DOES NOT have 4.5 to 5 Volts. Double check all of your connections and repeat the test.

If your multimeter still doesn't register the 4.5 to 5 Volts DC, then this test result tells you that the TPS itself is not at fault (and thus causing the TPS trouble code). Without power, the TPS can't create a throttle angle voltage signal. Although beyond the scope of this tutorial, your next step is to diagnose and restore this missing power.

TEST 3: Verifying Throttle Position Sensor Has Ground

So far, your TPS diagnostic tests have confirmed that:

• A TPS trouble code illuminating the check engine light (P0121, P0122, P0123).
• The throttle angle voltage signal the TPS is creating IS NOT increasing/decreasing as you manually open/close the throttle plate (TEST 1).
• The TPS is getting power on the GRY/RED wire of its electrical connector (TEST 2).

The next step is to see if the GRY/YEL wire of the TPS connector is feeding Ground to the TPS. We'll check for this Ground by doing a multimeter voltage test.

IMPORTANT: Ground is provided directly by the fuel injection computer. Be careful and don't intentionally or accidentally short this wire (circuit) to battery power or you will fry the fuel injection computer.

OK, here are the test steps:

1. 1

   Set your multimeter to Volts DC mode.

2. 2

   Probe the GRY/YEL wire of the TPS connector. The GRY/YEL wire connects to TPS pin #3 (see illustration above).
   
   NOTE: Be careful not to damage the terminal if you probe it on the front of the connector. If possible, you should use a back probe or a wire-piercing probe to check this circuit.

3. 3

   Now, with the red multimeter test lead, probe the battery positive (+) terminal.

4. 4

   Turn the key to its ON position but don't start the engine. This will power up the fuel injection computer.

5. 5

   Your multimeter will display 11 to 12 Volts if terminal B is feeding the TPS with Ground.

CASE 1: The GRY/YEL wire is feeding the TPS Ground. This confirms the TPS is getting Ground from the PCM.

Taking into account the test results of all 3 test, you have confirmed that:

1. The TP sensor is not providing a varying voltage signal when manually opening the throttle plate.
2. The TP sensor is being fed 5 Volts DC.
3. The TP sensor is being fed Ground.

So, you can now conclude that the throttle position sensor is bad and needs to be replaced. This will also solve the trouble code lighting up the check engine light on your 2.5L Grand Vitara's instrument cluster.

CASE 2: The GRY/YEL wire IS NOT feeding the TPS Ground. Double check that you're testing the correct TP sensor harness terminal wire and repeat the test.

If your test result still indicates that the TPS is not getting Ground, then we can conclude that one of two things are causing this lack of Ground:

1. There's an open in the wire between the TP sensor harness connector and the fuel injection computer's harness connector.
2. The fuel injection computer has an internal problem (although this is extremely rare).

Although testing these two conditions are beyond the scope of this article, you have now eliminated the throttle position sensor (TPS) on your 2.5L Suzuki Grand Vitara as being the cause of the problem and/or the TP sensor diagnostic trouble code (DTC) lighting up the check engine light (CEL).

How To Adjust The Grand Vitara TPS

The TPS, on the 2.5L Grand Vitara (Chevy Tracker) covered by this tutorial, has to be adjusted if removed and replaced.

The adjustment procedure is easy and below you'll find it explained in a step-by-step way:

1. Tap into the RED/GRN wire of the TPS with the red multimeter test lead.
   • The TP sensor must remain connected to its connector during the whole adjustment procedure.
2. Ground the black multimeter test lead on the battery negative (-) terminal.
3. Turn the key to the ON position but don't crank or start the engine.
4. Your multimeter should read 0.35 to 0.65 Volts DC with the throttle plate closed.
   • If the multimeter does not read 0.35 to 0.65 Volts DC, then the TPS is not adjusted to specification.
5. To adjust the TPS:
   • Loosen the TPS screws.
   • Rotate the TPS till your multimeter registers 0.35 to 0.65 Volts and tighten the screws.
6. After tightening the TPS screws, check the voltage reading on the RED/GRN wire to make sure it's within the indicated specification.
7. After the TPS adjustment is done, reset the fuel injection computer by disconnecting the battery negative cable from the battery for about 10 seconds. This is a very important step for the computer to recognize the new closed throttle plate angle voltage value as 0 degrees!