How To Test The TPS (1995-1998 1.5L Mazda Protege)

TEST 2: Making Sure The TPS Has 5 Volts

So far, in TEST 1, you've confirmed that the throttle position sensor is not producing a voltage signal that increases/decreases as you open/close the throttle plate.

There's a good chance that the throttle position sensor might not be receiving 5 Volts DC from the fuel injection computer.

So, in this test section we're going to make sure that the light green with red stripe (LT GRN/RED) wire is supplying 5 Volts DC to the TPS.

In the photo above, the LT GRN/RED wire connects to the female terminal labeled with the no. 1.

If 5 Volts are present in the LT GRN/RED wire, then we can move on to the next test which is making sure that the throttle position sensor is receiving Ground.

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

   With the red multimeter test lead (using the appropriate tool), gently probe the female terminal labeled with the number 1.
   
   Terminal no. 1 connects to the LT GRN/RED wire of the connector.

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 analyze your test results:

CASE 1: The LT GRN/RED wire is feeding the TPS with 5 Volts. This is the correct test result.

Now that you have confirmed that your 1.5L Mazda Protege's TPS is getting 5 Volts, the next step is to make sure it's getting Ground. Go to: TEST 3: Making Sure The TPS Has Ground.

CASE 2: The LT GRN/RED wire IS NOT feeding the TPS with 5 Volts. Without these 5 Volts the TPS, on your 1.5L Mazda Protege, will not function.

These missing 5 Volts are usually the result of an open-circuit problem in the LT GRN/RED wire between the TPS sensor's connector and the fuel injection computer's connector.

TEST 3: Making Sure The TPS Has Ground

If you've reached this point, your TPS diagnostic test results have confirmed that:

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

For our third and last test, we're gonna' make sure that the throttle position sensor is receiving Ground from the fuel injection computer.

The wire that supplies Ground do the TPS, is the black with red stripe (BLK/RED) wire of the sensor's 3-wire connector.

In the photo above, the BLK/RED wire connects to the female terminal labeled with the no. 3.

To test for the presence of Ground in the BLK/RED wire, we're gonna' to do a simple multimeter voltage test.

NOTE: Ground is provided by the fuel injection computer of your 1.5L Mazda Protege. Be careful and don't connect this wire to battery 12 Volts or you'll fry the fuel injection computer. The multimeter voltage test I'm suggesting below is a safe way to test for the presence of Ground in the 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

   With the black multimeter test lead (using the appropriate tool), gently probe the terminal labeled with the number 3.
   
   Terminal no. 3 connects to the BLK/RED wire of the connector.

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 analyze your test results:

CASE 1: The BLK/RED wire is feeding Ground to the TPS. This is the correct test result.

You can correctly conclude that the TPS is defective if you have:

• Confirmed that the TPS voltage signal does not increase/decrease as you opened/closed the throttle plate (TEST 1).
• Confirmed that the TPS is getting 5 Volts (TEST 2).
• Confirmed, in this test section, that the TPS is getting Ground.

CASE 2: The BLK/RED wire IS NOT feeding Ground to the TPS. Without Ground the TPS will not function.

This missing Ground is usually caused by an open-circuit problem in the BLK wire between the throttle position sensor's connector and the fuel injection computer's connector.

More 1.5L Mazda Protege Tutorials

You can find a complete list of 1.5L Mazda Protege tutorials in this index:

• Mazda 1.5L Index Of Articles.

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

• Ignition System Wiring Diagram (1995 1.5L Mazda Protege).
• MAF Sensor Circuit Wiring Diagram (1996-1998 1.5L Mazda Protege).
• How To Test The MAF Sensor (1996-1998 1.5L Mazda Protege).