How To Test The Throttle Position Sensor (1995-1996 1.5L Toyota Tercel)

TEST 2: Making Sure The TPS Has 5 Volts

If in TEST 1, the throttle position sensor signal did not increase/decrease as you opened/closed the throttle plate, then there's a good chance that it might not be getting 5 Volts on the light green with red stripe (LT GRN/RED) wire of its 4-wire connector.

So in this test section we're going to make sure that the LT GRN/RED wire is feeding the throttle position sensor with 5 Volts DC.

If your Toyota Tercel's throttle position sensor is getting 5 Volts DC, then the next step is to make sure that it's getting Ground on the brown (BRN) wire of its 4-wire connector (TEST 3).

These are the test steps:

1. 1

   Place your multimeter in Volts DC mode.

2. 2

   Disconnect the TPS from its electrical connector.

3. 3

   Turn the key on but don't start the engine.

4. 4

   Connect the red multimeter test lead (using the appropriate tool) to the LT GRN/RED wire.

5. 5

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

6. 6

   Your multimeter should read 4.5 to 5 Volts DC.

Let's examine your test results:

CASE 1: The multimeter registered 4.5 to 5 Volts. This is the correct test result and confirms that the throttle position sensor (TPS) is getting power from your Toyota Tercel's fuel injection computer.

The next and last test, is to make sure that the throttle position sensor is getting Ground (from the fuel injection computer too). For this test, go to: TEST 3: Making Sure The TPS Has Ground.

CASE 2: Your 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 this test result tells you that the TPS itself is not bad. 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 these missing 5 Volts.

TEST 3: Making Sure The TPS Has Ground

So far your test results have confirmed that:

• The throttle position sensor is not creating a voltage signal that increases/decreases as you open/close the throttle plate (TEST 1).
• The throttle position sensor is getting 5 Volts DC on the LT GRN/RED (TEST 2).

For our last test we're going to make sure that the brown (BRN) wire is providing Ground from the fuel injection computer.

To verify the presence of Ground in the BRN wire we're going to do a simple multimeter voltage test.

IMPORTANT: Be careful and do not accidentally or intentionally connect this Ground wire to battery voltage or you'll fry the fuel injection computer on your 1.5L Toyota Tercel. The multimeter voltage test I'm suggesting in the test instructions is a safe way to check for the presence of Ground in the BRN wire.

Let's get started:

1. 1

   Place your multimeter in Volts DC mode.

2. 2

   Disconnect the TPS from its electrical connector.

3. 3

   Turn the key on but don't start the engine.

4. 4

   Connect the black multimeter test lead (using the appropriate tool) to the BRN wire.

5. 5

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

6. 6

   Your multimeter should read 10 to 12 Volts DC.

Let's interpret your test results:

CASE 1: The multimeter showed 10 to 12 Volts. This is the correct test result and it tells you that the throttle position sensor, on your 1.5L Toyota Tercel, is getting Ground.

You can correctly conclude that the TPS is bad, and needs to be replaced, if you have confirmed that:

1. The TP sensor is not producing a voltage signal that increases/decreases as you open/close the throttle plate.
2. The TP sensor is being fed 5 Volts DC.
3. The TP sensor is being fed Ground.

NOTE: After replacing the TPS you'll need to adjust it to the correct specification.To adjust the TPS, this tutorial will help: TPS Idle Switch Multimeter Test (1995-1996 1.5L Toyota Tercel).

CASE 2: Multimeter DID NOT show 10 to 12 Volts. Double check that you're testing the correct terminal wire and repeat the test. If your multimeter still doesn't show the indicated voltage then you can conclude that the TPS is not getting Ground.

Without Ground the TPS will not function and the fuel injection computer will set a TPS trouble code.

Although testing for this lack of Ground is beyond the scope of this tutorial, you have now eliminated the throttle position sensor (TPS) on your 1.5L Toyota Tercel as being the cause of the problem and/or the TPS diagnostic trouble code (DTC) lighting up the check engine light (CEL).

More 1.5L Toyota Tutorials

There are several more ‘how to’ tutorials that I've written that are 1.5L Toyota specific, that may be of further help. You can find the ones that are located here, at this site, by going to the Toyota 1.5L Index Of Articles.

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

• How To Test The Ignitor -Step By Step (1995-1996 1.5L Toyota Tercel).
• How To Test Engine Compression (1.5L Toyota Tercel).
• How To Test The Fuel Injectors (1995-1996 1.5L Toyota Tercel).
• How To Test For A Blown Head Gasket (1.5L Toyota Tercel).