TEST 2: Verifying Throttle Position Sensor Has Power

Making Sure The TPS Is Getting Power. How To Test The Throttle Position Sensor -TPS- (1998, 1999, 2000, 2001 1.3L Suzuki Swift / Chevy Metro) Making Sure The TPS Is Getting Power. How To Test The Throttle Position Sensor -TPS- (1998, 1999, 2000, 2001 1.3L Suzuki Swift / Chevy Metro)

If you've reached this point, you have confirmed that:

One: A TPS diagnostic trouble code (P0121, P0122, P0123) is lighting up the check engine.

Two: That the TPS is not creating an increasing/decreasing throttle angle voltage signal as you open and close the throttle plate.

Now, we need to make sure that the throttle position sensor (TPS) is getting power. This power is supplied by the PCM and is in the form of 5 Volts DC.

The LT GRN wire of the TP sensor connector is the one that feeds these 5 Volts DC to the sensor.

NOTE: You can test for these 5 Volts DC with the TP sensor connected or disconnected to the TP sensor. I personally prefer to do this test with the TP sensor's connector unplugged.

This is what you'll need to do:

  1. 1

    Disconnect the TPS from its connector.

  2. 2

    Place your multimeter's dial in Volts DC mode.

  3. 3

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

    This will power up the TP sensor's connector.

  4. 4

    Connect the red multimeter test lead to the LT GRN wire.

    IMPORTANT If you probe the front of the TP sensor harness connector, be careful and don't damage the terminal. Damaging the terminal will require that you replace the connector.

  5. 5

    Connect the black multimeter test lead to the negative (-) battery terminal.

  6. 6

    When you've set up the test, have a helper turn the key to the ON position but don't crank or start the engine.

  7. 7

    Your multimeter should display 4.5 to 5 Volts on its screen.

Let's interpret your test results:

CASE 1: The multimeter registered 4.5 to 5 Volts. So far so good since this tells you that the throttle position sensor (TPS) is getting power from the powertrain control module (PCM).

The next step (and the last test) is to check that the LT GRN/BLK wire (which connects to terminal number 1 of the TP sensor's harness connector) is providing Ground. For this test, go to: TEST 3: Verifying Throttle Position Sensor Has Ground.

CASE 2: Multimeter DID NOT register 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 you've just eliminated the TP sensor itself, on your Suzuki, as bad. The two most likely reasons for this are: 1) an open in the wire between the TP sensor's harness connector and the PCM's harness connector or 2) the PCM may be fried (although a bad PCM is very rare).

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

TEST 3: Verifying Throttle Position Sensor Has Ground

Making Sure The TPS Is Getting Ground. How To Test The Throttle Position Sensor -TPS- (1998, 1999, 2000, 2001 1.3L Suzuki Swift / Chevy Metro) Making Sure The TPS Is Getting Ground. How To Test The Throttle Position Sensor -TPS- (1998, 1999, 2000, 2001 1.3L Suzuki Swift / Chevy Metro)

Up to this point, you have checked and confirmed that:

One: A TPS trouble code (P0121, P0122, P0123) is lighting up the check engine light (CEL).

Two: Is not creating an appropriate vacuum voltage signal (TEST 1).

Three: That the sensor is getting power in the form of 5 Volts from the LT GRN wire (TEST 2).

To finish our TP sensor diagnostic tests, the last thing we need to do is to check that the LT GRN/BLK wire is providing Ground to the TP sensor.

OK, here are the test steps:

  1. 1

    Disconnect the TPS from its connector.

  2. 2

    Place your multimeter's dial in Volts DC mode.

  3. 3

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

    This will power up the TP sensor's connector.

  4. 4

    Probe the LT GRN/BLK wire with the black multimeter test lead.

    Be careful not to damage the terminal if you probe it on the front of the connector.

  5. 5

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

  6. 6

    Have your helper turn the key to its ON position but don't start the engine.

  7. 7

    Your multimeter will display 10 to 12 Volts.


Let's interpret your multimeter test results:

CASE 1: The multimeter showed 10 to 12 Volts. This confirms that the PCM and the wire/circuit (that supply this Ground) are OK.

All three test 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.

Therefore, you can conclude that the throttle position sensor is bad and needs to be replaced (and that this will solve the TP sensor code lighting up the check engine light).

CASE 2: Multimeter DID NOT show 10 to 12 Volts. Double check that you're testing the correct TP sensor harness terminal wire and repeat the test.

If your multimeter still doesn't show the indicated voltage, then this indicates a problem with either your Suzuki's PCM (internal fault/problem) or an open in the wire between the TP sensor harness connector and the PCM's harness connector

Although testing these two conditions are beyond the scope of this article, you have now eliminated the throttle position sensor (TPS) on your Suzuki as being the cause of the problem and/or the TP sensor diagnostic trouble code (DTC) lighting up the check engine light (CEL). You can use the wiring diagram found in the following article to check continuity of the TP sensor circuits:

  1. 1998-2001 TP Sensor Circuit Diagram (1.3L Swift / Metro).

More 1.3L Swift (Chevy Metro) Tutorials

You can find a complete list of tutorials in this index: Suzuki 1.3L Index Of Articles.

Here's a small sample of the 1.3L Swift tutorials you'll find in the index:

  1. How To Test The MAP Sensor (1998-2001 1.3L Swift / Chevy Metro).
  2. How To Test The Ignition Coils Suzuki: Swift, Vitara - Chevy: Metro, Tracker (at: easyautodiagnostics.com).
  3. How To Troubleshoot A Misfire (Suzuki 1.3L, 1.6L, 1.8L, 2.0L, 2.3L) (at: easyautodiagnostics.com).
  4. How To Do A Compression Test (Suzuki 1.3L, 1.6L, 1.8L, 2.0L, 2.3L) (at: easyautodiagnostics.com).
  5. Blown Head Gasket Test (Suzuki 1.3L, 1.6L, 1.8L, 2.0L, 2.3L, 2.5L) (at:easyautodiagnostics.com).
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