The 24X crankshaft position (CKP) sensor is located behind the crankshaft pulley balancer and it can be tested with a simple multimeter -no scan tool required!
In this tutorial, I'm gonna' show you the 3 tests you'll need to perform to find out if it's bad (or not).
NOTE: The 24X CKP sensor is also known as the high resolution CKP sensor.
Contents of this tutorial:
- Symptoms Of A Bad 24X Crankshaft Position (CKP) Sensor.
- Circuit Descriptions Of The Crankshaft Position Sensor.
- Where To Buy The 24X Crankshaft Position Sensor.
- TEST 1: Testing The 24X Crankshaft Position Signal.
- TEST 2: Making Sure The 24X CKP Sensor Has Power.
- TEST 3: Making Sure The 24X CKP Sensor Has Ground.
You can find this tutorial in Spanish here: Cómo Probar El Sensor 24X CKP (1995-1999 3.1L V6 Chevrolet Lumina, Monte Carlo) (at: autotecnico-online.com).
APPLIES TO: This tutorial applies to the following vehicles since they use the exact same 24X crankshaft position (CKP) sensor:
- 3.1L V6 Chevrolet Lumina: 1995, 1996, 1997, 1998, 1999.
- 3.1L V6 Chevrolet Monte Carlo: 1995, 1996, 1997, 1998, 1999.
RELATED TUTORIALS: The following tutorial will help you test the ignition coil packs and the ignition control module:
- How To Test The Ignition Coil Packs (GM 3.1L, 3.4L).
- Testing The Ignition Module and Crank Sensor (GM 3.1L, 3.4L).
WIRING DIAGRAMS: You can find the ignition system wiring diagrams here:
- Ignition System Circuit Diagram (1995 3.1L V6 Chevrolet Lumina, Monte Carlo) .
- Ignition System Circuit Diagram (1996 3.1L V6 Chevrolet Lumina, Monte Carlo) .
- Ignition System Circuit Diagram (1997 3.1L V6 Chevrolet Lumina, Monte Carlo) .
- Ignition System Circuit Diagram (1998-1999 3.1L V6 Chevrolet Lumina, Monte Carlo) .
Symptoms Of A Bad 24X Crankshaft Position (CKP) Sensor
The 24X CKP sensor is not involved in starting the engine. It's purpose is to allow the fuel injection computer to determine a more precise crankshaft position at lower RPM (under 2000 RPM).
When it fails, you'll see one or more of the following trouble codes lighting up the check engine light:
- Code 36: Ignition Control 24X Signal Circuit Error (1995 OBD I system).
- P0336: 24X Reference Signal Circuit (1996+ OBD II system).
You may also see one of the following symptoms:
- Rough idle.
- Engine may start and stall.
If your 3.1L Chevrolet Lumina (Monte Carlo) is not starting, more than likely the 24X CKP is not at fault. Still, I recommend testing it since its test procedure is not difficult.
Circuit Descriptions Of The Crankshaft Position Sensor
The 24X crankshaft position sensor is a 3-wire sensor and it's a Hall Effect sensor. As such, it needs power and Ground to generate its position signal.
Power is in the form of 12 Volts DC. This voltage is either provided by a fuse or the fuel injection computer (see tables below).
Ground is provided by the fuel injection computer.
The connector on the sensor itself has male spade terminals. The connector on the engine wiring harness has female terminals.
The following table has a brief job description of each of the 3 wires of the 24X CKP sensor.
| 1996 24X CKP Sensor Connector | ||
|---|---|---|
| Pin | Wire Color | Description |
| A | Pink (PNK) | 12 Volts (provided by F/INJ fuse) |
| B | Light blue with black stripe (LT BLU/BLK) | 24X CKP Signal |
| C | Pink with black stripe (PNK/BLK) | Ground (provided by PCM) |
| 1996-1999 24X CKP Sensor Connector | ||
|---|---|---|
| Pin | Wire Color | Description |
| A | Red with white stripe (RED/WHT) | 12 Volts (provided by PCM) |
| B | Light blue with black stripe (LT BLU/BLK) | 24X CKP Signal |
| C | Black (BLK) | Ground (provided by PCM) |
Where To Buy The 24X Crankshaft Position Sensor
Checkout the following links and comparison shop the 24X crankshaft position sensor for your 1995-1999 V6 Chevrolet Lumina (Monte Carlo) of the 2 best known automotive parts manufacturers (Standard Motor Products and AC-Delco):
Important Safety Precautions And Tips
TIP 1: If you raise your vehicle with a jack, use jack stands! Don't trust the jack to keep the vehicle raised.
TIP 2: If the engine has been running for any length of time, let it cool down completely before starting this test.
Why? Because the 24X CKP sensor's pigtail connector is located under the exhaust manifold (radiator side). The exhaust manifold can get very hot and cause severe burns!
TIP 3: The 24X CKP sensor test described in this tutorial is an on-car test. You should not remove it to test it.
TIP 4: Turn the engine by hand, using the appropriate tools on the crankshaft pulley bolt. Do not use the starter motor to crank the engine during TEST 1.
TEST 1: Testing The 24X Crankshaft Position Signal
The 24X crankshaft position sensor produces an ON/OFF voltage signal, when the engine is turning, that can easily be confirmed with a multimeter.
To be a bit more specific ON is when the 24X CKP signal is at 10-12 Volts DC. And OFF is when the 24X CKP signal is at 0 Volts.
To test for this ON/OFF voltage signal with a multimeter, you'll need to turn the engine manually. In other words you cannot use the starter motor.
If the 24X crankshaft position sensor is bad, then it's going to stay stuck producing a single voltage value as we turn the engine.
In other words, the crankshaft position sensor is not going to produce the ON/OFF voltage signal as you manually turn the engine.
LOCATION OF THE 24X CKP SENSOR: The 24X CKP sensor is located behind the crankshaft pulley balancer.
IMPORTANT: The 24X sensor must be connected to its engine harness connector for this test to work. You'll need to connect your multimeter test lead to a back probe or a wire piercing probe to read the crank signal. You can see an example of a wire piercing probe here: Wire Piercing Probe Review (Power Probe PWPPPPP01).
NOTE: Don't have a multimeter or need to upgrade yours? Check out my recommendation: Buying A Digital Multimeter For Automotive Diagnostic Testing.
These are the test steps:
- 1
Raise the front passenger side of the vehicle and place it on a jack-stand.
- 2
Remove the water splash shield to access the crankshaft pulley bolt.
This is the plastic splash shield that protects the crankshaft pulley and drive belt from water splash. - 3
Place your multimeter in Volts DC mode.
- 4
Connect the black multimeter test lead to the battery negative (-) terminal.
- 5
Connect the red multimeter test lead to the LT BLU/BLK wire wire of the 24X CKP sensor connector.
The LT BLU/BLK wire is on the engine wiring harness side of the connector.
NOTE: The 24X CKP sensor must remain connected to its engine wiring harness connector to be able to read its signal. - 6
Turn the ignition key to the ON position but don't crank or start the engine.
- 7
Slowly turn the engine by hand using a 1/2" ratchet wrench and appropriate socket on the crankshaft pulley bolt. For the accuracy of the test, do not use the starter motor.
- 8
Your multimeter should read an ON/OFF voltage of 5 Volts and 0 Volts as you turn the engine.
ON is when the multimeter reads 4-5 Volts DC and OFF is when it reads 0 Volts DC.
Let's examine your CKP signal test result:
CASE 1: The multimeter read the indicated ON/OFF DC voltage. This is the correct and expected test result and tells you that the 24X crankshaft position sensor is functioning correctly.
CASE 2: The multimeter DID NOT read the indicated ON/OFF DC voltage. This test result usually means that the 24X CKP sensor is defective.
Before you replace it, make sure it's getting power and Ground. For the next test go to: TEST 2: Making Sure The 24X CKP Sensor Has Power.