How To Test The 24X Crankshaft Position Sensor (1995-1999 3.1L V6 Chevrolet Lumina, Monte Carlo)

TEST 2: Making Sure The 24X CKP Sensor Has Power

If in TEST 1 the 24X CKP sensor, on your Chevrolet Lumina (Monte Carlo), did not produce an ON/OFF voltage signal then there's a good chance that it might not be receiving power.

The wire that provides this power (12 Volts) is the:

• 1995 3.1L Lumina (Monte Carlo): The pink (PNK) wire of the engine wiring harness connector.
• 1996-1999 3.1L Lumina (Monte Carlo): The red with white stripe (RED/WHT) wire of the engine wiring harness connector.

The RED/WHT (or PNK) wire connects to the male terminal labeled with the letter A in the photo above.

If the 24X CKP sensor is getting 10 to 12 Volts DC, then our next step is to make sure that it's getting Ground in TEST 3.

NOTE: Be very careful not to damage the female terminal of the connector with your multimeter test leads.

IMPORTANT: This test is done on the engine wiring harness connector of the sensor. The engine wiring harness connector has female terminals.

These are the test steps:

1. 1

   Disconnect the 24X CKP sensor from its connector.

2. 2

   Place your multimeter in Volts DC mode.

3. 3

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

4. 4

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

5. 5

   Gently probe the female terminal of the connector that connects to the RED/WHT (or PNK) wire.
   
   NOTE: This test is done on the engine wiring harness connector that has female terminals.

6. 6

   Your multimeter should read 10 to 12 Volts DC.

Let's examine your test result:

CASE 1: The 24X CKP sensor is getting power. This is the correct and expected test result.

The next and last test is to make sure that the 24X CKP sensor is receiving Ground. Go to: TEST 3: Making Sure The 24X CKP Sensor Has Ground.

CASE 2: The 24X CKP sensor is not getting power. Without this voltage the 24X crankshaft position sensor will not produce an ON/OFF signal.

The most likely cause of these missing 12 Volts is an open-circuit problem in the RED/WHT (or PNK) wire between the 24X CKP sensor's connector and the fuel injection computer's connector (or the underhood electrical center #1 -1995 Lumina and Monte Carlo).

Although it's beyond the scope of this tutorial to check for this missing power, your next step is to find out why it's missing and restore it.

TEST 3: Making Sure The 24X CKP Sensor Has Ground

Your previous two tests have confirmed that:

• The 24X crankshaft position sensor is not creating an ON/OFF signal (TEST 1).
• The 24X crankshaft position sensor is getting 10 to 12 Volts DC (TEST 2).

For our last test we're going to make sure that the CKP sensor is getting Ground.

This Ground is provided to the 24X CKP sensor by the:

• 1995 3.1L Chevy Lumina, Monte Carlo:
  • Pink with black stripe (PNK/BLK) wire of the sensor's engine wiring harness connector.
• 1996-1999 3.1L Chevy Lumina, Monte Carlo:
  • Black (BLK) wire of the sensor's engine wiring harness connector.

The BLK (or PNK/BLK) wire connects to the male terminal labeled with the letter C in the photo above.

To test for the presence of Ground in the BLK (or PNK/BLK) wire, we're going to do a simple multimeter voltage test just like the one we did to check for the presence of 12 Volts DC in the RED/WHT wire in TEST 2.

IMPORTANT: Be careful and don't short this Ground wire to battery power or you'll fry the fuel injection computer. The multimeter voltage test suggested below (for testing the presence of Ground) is a safe and accurate way to test for the presence of Ground in the wire.

NOTE: Be very careful not to damage the female terminal of the connector with your multimeter test leads.

IMPORTANT: This test is done on the engine wiring harness connector of the sensor. The engine wiring harness connector has female terminals.

These are the test steps:

1. 1

   Disconnect the 24X CKP sensor from its connector.

2. 2

   Place your multimeter in Volts DC mode.

3. 3

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

4. 4

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

5. 5

   Gently probe the female terminal of the connector that connects to the BLK (or PNK/BLK) wire.
   
   NOTE: This test is done on the engine wiring harness connector that has female terminals.

6. 6

   Your multimeter should read 10 to 12 Volts DC if Ground is present in the wire.

Let's take a look at what your test results mean:

CASE 1: Ground is present in the BLK (or PNK/BLK) wire. This is the correct and expected test result.

You can now conclude that the 24X crankshaft position (CKP) sensor is defective if you have:

• Confirmed that the 24X CKP sensor is not creating an ON/OFF signal (TEST 1).
• Confirmed that the 24X CKP sensor sensor is getting power (TEST 2).
• Confirmed that the 24X CKP sensor sensor is getting Ground (this test section).

CASE 2: Ground is NOT present in the BLK (or PNK/BLK) wire. Without Ground the 24X CKP sensor will not produce an ON/OFF signal.

The most likely cause of this missing Ground is an open-circuit problem in the BLK (or PNK/BLK) wire between the CKP sensor's connector and the fuel injection computer's connector.

Although it's beyond the scope of this tutorial to check for this missing Ground, your next step is to find out why it's missing and restore it.